CN103457576B - The remote control of high accuracy RC oscillators and built-in high accuracy RC oscillators - Google Patents
The remote control of high accuracy RC oscillators and built-in high accuracy RC oscillators Download PDFInfo
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Abstract
The invention discloses a kind of high accuracy RC oscillators, it is built-in with the remote controller chip and the remote control including the remote controller chip of the RC oscillators, on the basis of existing RC oscillators, the RC oscillators further include tc compensation unit and voltage coefficient compensating unit, and tc compensation unit includes the first trap resistance and the second trap resistance；One end of first trap resistance is connected with one end of the first electric capacity and the input of first switch device respectively, and the other end of the first trap resistance is connected with the output end of the first constant-current source；One end of second trap resistance is connected with one end of the second electric capacity and the input of second switch device respectively, and the other end of the second trap resistance is connected with the output end of the second constant-current source.Using trap positive temperature coefficient of resistance come the negative temperature coefficient of frequency in compensated oscillator, so as to obtain the RC oscillators of zero-temperature coefficient so that RC oscillators are desirably integrated into remote controller chip.
Description
Technical Field
The invention relates to an electronic device and a circuit, in particular to a high-precision RC oscillator and a remote controller with the high-precision RC oscillator built in.
Background
In the conventional remote controller, as shown in fig. 1, the remote controller generally includes a remote controller chip 110, and an infrared transmitting tube 120, an oscillator 130, an electrolytic capacitor 140, and a transistor 150 disposed outside the remote controller chip 110. However, in order to cope with the increasing raw material cost and labor cost, it is urgently required that one or more of the infrared transmitting tube 120, the oscillator 130, and the electrolytic capacitor 140 provided outside the remote controller chip 110 be omitted or integrated into the remote controller chip 110.
For example, for the oscillator 130, if it is integrated into the remote control chip 110, the influence of the temperature coefficient, the power coefficient and the process parameter drift of the oscillator 130 during the operation process needs to be solved. Fig. 2 shows a circuit schematic of an RC oscillator commonly used in a remote controller in the prior art, and as shown in fig. 2, the RC oscillator includes:
a reference constant current source 211 and a reference resistor 212, wherein one end of the reference resistor 212 is connected to the output end of the reference constant current source 211, and the other end is grounded;
the circuit comprises a first constant current source 231, a first capacitor 232 and a first switching device 233, wherein one end of the first capacitor 232 and the input end of the first switching device 233 are respectively connected with the output end of the first constant current source 231, and the other end of the first capacitor 232 and the output end of the first switching device 233 are respectively grounded;
a second constant current source 241, a second capacitor 242, and a second switching device 243, wherein one end of the second capacitor 242 and an input end of the second switching device 243 are connected to an output end of the second constant current source 241, respectively, and the other end of the second capacitor 242 and an output end of the second switching device 243 are grounded, respectively;
a comparison unit 220 and an output inverter, wherein an input terminal of the comparison unit 220 is connected to an output terminal of the reference constant current source 211, an output terminal of the first constant current source 231, and an output terminal of the second constant current source 241, an output terminal of the comparison unit 220 is connected to a control terminal of the first switching device 233 and an input terminal of the output inverter, an output terminal of the output inverter is connected to a control terminal of the second switching device 243 and an output terminal 260 of the RC oscillator, so that the comparing unit 220 compares the charging voltages (Va and Vb) of the first and second capacitors 232 and 242 with the reference voltage (REF) outputted from the reference constant current source 211, the first and second capacitors 232 and 242 are controlled to alternately discharge to generate an output signal (Vc) by generating a control signal when the charging voltage is equal to the reference voltage and outputting the control signal to the control terminal of the first switching device 233 and the control signal to the control terminal of the second switching device 243 through the output inverter. Fig. 3 shows the time-dependent curves of Va, Vb and Vc, and it can be seen from fig. 3 that the first capacitor 232 and the second capacitor 242 are alternately charged from 0V and discharged when the charging voltage reaches the reference voltage REF, thereby generating the output signal Vc through the alternate charging and discharging of the first capacitor 232 and the second capacitor 242.
In this process, the frequency of the output signal depends on the R, C values (time constant) of the resistor capacitor. However, the temperature coefficient of the reference resistor 212 in the RC oscillator is relatively large, and the working temperature range of the remote controller chip 110 is usually-20 ℃ to 70 ℃, if the RC oscillator is directly integrated into the remote controller chip, the resistance R increases when the temperature rises, which causes the reference voltage REF to rise, the charging time to increase, and the frequency to slow. In addition, the power coefficient of the capacitor in the RC oscillator is large, particularly the capacitor prepared by adopting a single-layer polysilicon process, the working voltage range of the remote controller chip is 2.0V-3.6V, and the value of the capacitor C in the RC oscillator is reduced along with the reduction of the voltage in the voltage range, so that the frequency is increased. Third, the process parameters of the capacitor and resistor in the RC oscillator drift greatly, for example, the resistor drifts ± 15%, the capacitor drifts ± 15%, and the frequency drifts ± 32%.
For the electrolytic capacitor, if the electrolytic capacitor is to be removed directly in the remote controller, it needs to consider how to filter the power supply (such as +3V power supply in fig. 1) so as to make the remote controller chip operate stably. In the working process, the current of the infrared transmitting tube is very large, when the output end (namely an OUT pin) of the remote controller chip is turned on or turned off, the phenomena of instantaneous voltage rising and voltage falling are very serious, so that the power supply is influenced, and the voltage of 3V can rise to more than 9V within dozens of nanoseconds. Fig. 4 shows the output voltage Vout and the power supply voltage Vdd of the remote control chip varying with time, and as shown in fig. 4, the jitter occurring at the instant when the output voltage of the remote control chip is turned on and off will cause the power supply voltage to jitter from 3V to 9V, so that the fast and large voltage jitter will seriously affect the internal logic of the remote control chip, cause disorder, and cause abnormal operation. Therefore, if the electrolytic capacitor is simply removed, the remote controller is unstable or even incapable of operating.
At present, in order to realize a built-in remote controller chip, a commonly adopted method is to prepare the remote controller chip by adopting a double-crystal double-aluminum process with high cost and complex process instead of a single-crystal single-aluminum process with low cost and simple process, and a band gap (bandgap) voltage stabilizing circuit is adopted in the remote controller chip. Although the method can solve the influence caused by the power coefficient and the process parameter drift of the oscillator, the influence caused by the temperature coefficient of the oscillator cannot be eliminated, and the electrolytic capacitor cannot be saved, so that the full built-in state cannot be really realized, namely, the external part of the remote controller chip only has an infrared transmitting tube. Meanwhile, the adoption of the double-crystal double-aluminum process not only increases the cost, but also puts higher requirements on preparation conditions due to the complex process.
Disclosure of Invention
The invention aims to solve the technical problem that in the prior art, an oscillator cannot be directly integrated into a remote controller chip due to the influence of the temperature coefficient of the oscillator, and provides a high-precision RC oscillator and a remote controller with the built-in high-precision RC oscillator.
The technical scheme adopted by the invention for solving the technical problems is as follows: according to an aspect of the present invention, there is provided a high-precision RC oscillator including:
the temperature compensation circuit comprises a reference constant current source, a reference resistor, a first constant current source, a first capacitor, a first switching device, a second constant current source, a second capacitor, a second switching device, a comparison unit, an output inverter and a temperature coefficient compensation unit;
the temperature coefficient compensation unit includes: a first well resistance and a second well resistance;
one end of the reference resistor is connected with the output end of the reference constant current source, and the other end of the reference resistor is grounded;
one end of the first capacitor and the input end of the first switching device are respectively connected with one end of the first trap resistor, the other end of the first capacitor and the output end of the first switching device are respectively grounded, and the other end of the first trap resistor is connected with the output end of the first constant current source;
one end of the second capacitor and the input end of the second switching device are respectively connected with one end of the second trap resistor, the other end of the second capacitor and the output end of the second switching device are respectively grounded, and the other end of the second trap resistor is connected with the output end of the second constant current source;
an input terminal of the comparing unit is connected to an output terminal of the reference constant current source, an output terminal of the first constant current source, and an output terminal of the second constant current source, respectively, an output terminal of the comparing unit is connected to a control terminal of the first switching device and an input terminal of the output inverter, respectively, and an output terminal of the output inverter is connected to a control terminal of the second switching device and an output terminal of the RC oscillator, respectively, so that the comparing unit compares a first voltage and a second voltage input from the input terminals connected to the output terminals of the first and second constant current sources, respectively, with the reference voltage output from the reference constant current source to generate a control signal based on the comparison, and outputs the control signal to the control terminal of the first switching device and the control signal to the control terminal of the second switching device through the output inverter, to control the first and second capacitors to alternately discharge to generate an output signal.
In the high-precision RC oscillator according to the embodiment of the present invention, the RC oscillator further includes an adjustable delay unit including a first inverter and a second inverter; wherein,
the input end of the first phase inverter is connected with the output end of the comparator, the output end of the first phase inverter is connected with the input end of the second phase inverter, and the output end of the second phase inverter is respectively connected with the control end of the first switching device and the input end of the output phase inverter;
the first phase inverter is an adjustable-width-to-length-ratio phase inverter.
In the high-precision RC oscillator according to the embodiment of the present invention, the RC oscillator further includes a trimming unit, and the trimming unit includes a trimming resistor; one end of the trimming resistor is connected with the output end of the reference constant current source, and the other end of the trimming resistor is connected with one end of the reference resistor.
In the high-precision RC oscillator according to the embodiment of the invention, the trimming resistor is a fuse resistor.
In the high-precision RC oscillator according to the embodiment of the present invention, the trimming unit further includes a first adjustable constant current source and a second adjustable constant current source; the output end of the first adjustable constant current source is connected with the output end of the first constant current source, and the output end of the second adjustable constant current source is connected with the output end of the second constant current source.
In a high-precision RC oscillator according to an embodiment of the present invention,
the first switch device is an N-channel MOS tube, and a grid electrode, a drain electrode and a source electrode of the N-channel MOS tube are respectively a control end, an input end and an output end of the first switch device;
the second switch device is an N-channel MOS tube, and a grid electrode, a drain electrode and a source electrode of the N-channel MOS tube are respectively a control end, an input end and an output end of the second switch device.
According to another aspect of the present invention, there is also provided a remote controller using the above-described high-precision RC oscillator, comprising a remote controller chip and an infrared transmitting tube; wherein
The output end of the remote controller chip is connected with the negative electrode of the infrared emission tube and used for providing an output signal to the infrared emission tube to serve as a driving electric signal, and the infrared emission tube emits an infrared remote control signal based on the driving electric signal;
the RC oscillator is integrated in the remote control chip.
In the remote controller according to the embodiment of the present invention, the remote controller chip includes a driving unit, an input end of the driving unit receives the output signal of the remote controller chip, and an output end of the driving unit is connected to an output end of the remote controller chip, so as to convert the output signal into the driving electric signal and output the driving electric signal to the output end of the remote controller chip; wherein,
the driving unit comprises a driving phase inverter and a driving MOS tube; the input end of the driving phase inverter receives an output signal of the remote controller chip, and the output end of the driving phase inverter is connected with the grid electrode of the driving MOS tube; the drain electrode of the driving MOS tube is connected with the output end of the remote controller chip, and the source electrode of the driving MOS tube is grounded;
and setting the width-length ratio of the driving phase inverter to prolong the opening and closing time of the output end of the remote controller chip.
In the remote controller according to an embodiment of the present invention, when the remote controller chip is manufactured by a single crystal single aluminum process, the width-to-length ratio of the driving inverter is smaller than the standard width-to-length ratio.
In the remote controller according to the embodiment of the invention, when the remote controller chip is prepared by adopting an aluminum gate process, the width-to-length ratio of the driving phase inverter is 0.5-5 times of the standard width-to-length ratio.
The invention has the following beneficial effects: during the capacitor discharge, the partial voltage action of the first and second well resistors set up makes V1 and V2 incompletely discharge, so the starting voltages of V1 and V2 charging are no longer 0 (i.e., the input voltages V1 and V2 of the comparison unit both vary from a small positive voltage other than 0 to the reference voltage REF). The larger the resistance of the trap resistor is, the higher the incomplete discharge is, the higher the starting point of the charge is, and the shorter the charge time is. In addition, the trap resistor has a large positive temperature coefficient, the resistance of which increases with increasing temperature, whereby the positive temperature coefficient of the trap resistor becomes a negative temperature coefficient of the charging time. When the temperature rises, the resistance value of the trap resistor increases, the charge starting point rises, and the charge time becomes short. However, the original reference resistor in the RC oscillator also has a positive temperature coefficient, and the resistance value thereof increases with the increase of the temperature, so that the reference voltage REF is raised, and the charging time is prolonged. The first and second well resistors are thus arranged to exactly compensate for the effect of the positive temperature coefficient of the reference resistor. Meanwhile, the positive temperature coefficient of the trap resistor is far greater than that of the original resistor in the RC oscillator, so that the trap resistor with very small resistance value can compensate the positive temperature coefficient of the original resistor. By properly adjusting the resistance of the well resistor, an RC oscillator with zero temperature coefficient can be obtained.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a prior art remote control;
FIG. 2 is a circuit schematic of a prior art RC oscillator;
FIG. 3 is a graph of the charging voltage of the first capacitor and the second capacitor of FIG. 2 and the output voltage of the RC oscillator over time;
FIG. 4 is a graph of the output voltage Vout and the supply voltage Vdd of the remote control chip of FIG. 1 over time;
FIG. 5 shows a circuit schematic of an RC oscillator according to a first embodiment of the present invention;
FIG. 6 is a graph of the output voltage of V1, V2, and the RC oscillator of FIG. 5 over time;
FIG. 7 is a graph of the frequency of the output voltage of FIG. 6 versus temperature;
FIG. 8 shows a circuit schematic of an RC oscillator according to a second embodiment of the present invention;
FIG. 9 is a graph of the frequency of the output voltage of the RC oscillator of FIG. 8 as a function of the supply voltage;
FIG. 10 shows a circuit schematic of an RC oscillator according to a third embodiment of the present invention;
FIG. 11 is a graph of the frequency of the output voltage of the RC oscillator of FIG. 10 as a function of trim bits;
FIG. 12 is a schematic diagram of a driving unit according to an embodiment of the invention;
fig. 13 is a graph of the output voltage Vout and the power supply voltage Vdd of the remote controller chip as a function of time after the driving unit of fig. 12 is employed;
fig. 14 is a schematic structural diagram illustrating a remote controller according to a preferred embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 5 shows a circuit schematic of an RC oscillator according to a first embodiment of the present invention, as shown in fig. 5, the RC oscillator includes:
a reference constant current source 211 and a reference resistor 212, wherein one end of the reference resistor 212 is connected to the output end of the reference constant current source 211, and the other end is grounded;
the constant current source circuit comprises a first constant current source 231, a first capacitor 232, a first switching device 233 and a first well resistor 510, wherein one end of the first capacitor 232 and the input end of the first switching device 233 are respectively connected with one end of the first well resistor 510, the other end of the first capacitor 232 and the output end of the first switching device 233 are respectively grounded, and the other end of the first well resistor 510 is connected with the output end of the first constant current source 231;
the second constant current source 241, the second capacitor 242, the second switching device 243 and the second well resistor 520, wherein one end of the second capacitor 242 and the input end of the second switching device 243 are respectively connected with one end of the second well resistor 520, the other end of the second capacitor 242 and the output end of the second switching device 243 are respectively grounded, and the other end of the second well resistor 520 is connected with the output end of the second constant current source 241;
a comparison unit 220 and an output inverter, wherein an input terminal of the comparison unit 220 is connected to an output terminal of the reference constant current source 211, an output terminal of the first constant current source 231, and an output terminal of the second constant current source 241, an output terminal of the comparison unit 220 is connected to a control terminal of the first switching device 233 and an input terminal of the output inverter, and an output terminal of the output inverter is connected to a control terminal of the second switching device 243 and an output terminal of the RC oscillator, respectively, so that the comparison unit 220 compares a first voltage and a second voltage (a first voltage, i.e., V1, a second voltage, i.e., V2) inputted from the input terminals connected to the output terminals of the first and second constant current sources 231 and 241 with the reference voltage (REF) outputted from the reference constant current source 211, generates a control signal when the first voltage (V1) or the second voltage (V2) is equal to the reference voltage, outputs the control signal to the control terminal of the first switching device 233 and outputs the control signal to the second switching device And a control terminal of a two-switch device 243 to control the first capacitor 232 and the second capacitor 242 to alternately discharge to generate an output signal (V3). In the RC oscillator, the first well resistor 510 and the second well resistor 520 constitute a temperature coefficient compensation unit.
Fig. 6 shows a graph of the RC oscillator with the temperature coefficient compensation unit comparing the input voltages V1 and V2 of the unit and the output voltage V3 of the RC oscillator over time according to an embodiment of the present invention. As can be seen from comparison with fig. 2, although V1 and V2 in fig. 6 still alternately rise to and fall from the reference voltage REF, they do not rise from 0V any more and do not end up falling at 0V any more, but rise from a small positive voltage at which they end up falling.
This is because the voltage dividing effect of the well resistor during the capacitor discharge makes V1 and V2 incompletely discharge, so the starting voltages of V1 and V2 charging are no longer 0 (i.e., the input voltages V1 and V2 of the comparison unit both vary from a small positive voltage other than 0 to the reference voltage REF). The larger the resistance of the trap resistor is, the higher the incomplete discharge is, the higher the starting point of the charge is, and the shorter the charge time is. It is well known that the well resistor has a large positive temperature coefficient, the resistance of which increases with increasing temperature, whereby the positive temperature coefficient of the well resistor becomes the negative temperature coefficient of the charging time. When the temperature rises, the resistance value of the trap resistor increases, the charge starting point rises, and the charge time becomes short. However, the original resistor (i.e. the reference resistor 212) in the RC oscillator also has a positive temperature coefficient, and the resistance value increases with the temperature, and the increase of the resistance value causes the reference voltage (REF) to rise, and the charging time is prolonged. Therefore, the first trap resistor and the second trap resistor are just arranged to compensate the influence caused by the positive temperature coefficient of the original resistor. The positive temperature coefficient of the trap resistor is far greater than that of the original resistor in the RC oscillator, so that the trap resistor with very small resistance value can compensate the positive temperature coefficient of the original resistor. By properly adjusting the resistance of the well resistor, an RC oscillator with zero temperature coefficient can be obtained. Fig. 7 is a graph of the frequency of the output voltage V3 of fig. 6 as a function of temperature, and it can be seen from fig. 7 that the frequency values remain substantially constant over a temperature range of-20 c to 70 c, achieving a zero temperature coefficient for the RC oscillator. It can be understood that according to the series principle of the circuit, since the well resistor is disposed between the input terminal of the comparing unit (the input terminal related to V1 and V2) and the ground, the input terminal voltages V1 and V2 of the comparing unit can not drop to 0 when the first capacitor and the second capacitor are discharged, so that the input terminal voltages V1 and V2 of the comparing unit rise from a smaller positive voltage, which is not 0, to the reference voltage REF when the first capacitor and the second capacitor are charged, thereby obtaining the temperature compensation.
Fig. 8 shows a circuit schematic diagram of an RC oscillator according to a second embodiment of the present invention, and as shown in fig. 8, the oscillator further includes an adjustable delay unit on the basis of the oscillator shown in fig. 5, and the adjustable delay unit includes a first inverter 810 and a second inverter 820. Wherein, the input end of the first inverter 810 is connected with the output end of the comparator, the output end of the first inverter 810 is connected with the input end of the second inverter 820, and the output end of the second inverter 820 is respectively connected with the control end of the first switching device 233 and the input end of the output inverter; the first inverter 810 is an inverter with an adjustable aspect ratio.
In the RC oscillator, the power coefficient of the capacitor (especially, the RC oscillator prepared by the single crystal single aluminum process) is large, which means that the capacitance value of the capacitor is sharply reduced along with the reduction of the power voltage. In operation, as the capacitance value decreases, the charging time of the capacitors (first capacitor 232 and second capacitor 242) decreases, such that the charging time of the oscillator exhibits a positive supply coefficient, i.e., the output frequency of the oscillator exhibits a negative supply coefficient. In the variation curve of the output frequency of the RC oscillator with the supply voltage shown in fig. 9, the curve 901 of the negative supply coefficient shows that the output frequency decreases with increasing supply voltage. In the prior art, the device delay is usually minimized to obtain better circuit performance, however, in contrast, an adjustable delay unit with a delay function is further provided in the RC oscillator, because the output frequency of the adjustable delay unit itself has a positive power coefficient, the delay gradually increases as the power supply voltage decreases, the charging time correspondingly increases, and the output frequency decreases. The supply factor of the charging time can be made 0 if the aspect ratio of the first inverter 810 in the adjustable delay cell is properly adjusted according to the specific structure and parameters of the RC oscillator. A supply factor curve 902 for the positive output frequency of the adjustable delay unit and a compensated supply factor curve 903 for a substantially 0 supply factor of the RC oscillator output after compensation by the adjustable delay unit are shown in fig. 9.
Since the aspect ratio of the first inverter 810 in the tunable delay unit can be adjusted according to specific situations, when the power coefficient of the capacitor itself has poor consistency, the power coefficient can be adjusted and calibrated according to the test data of each IC. Multiple test of the current sheet proves that the power coefficient is controlled within +/-0.5%, and the zero power coefficient can be obtained by increasing the adjustable range when needed.
In order to eliminate the offset of the output frequency of the RC oscillator caused by the drift of the process parameters of the resistor and the capacitor, the RC oscillator according to the third embodiment of the present invention further includes a trimming unit, as shown in fig. 10, the trimming unit includes a trimming resistor 1010; one end of the trimming resistor 1010 is connected to the output end of the reference constant current source 211, and the other end is connected to one end of the reference resistor 212, and the trimming resistor 1010 is preferably a fuse resistor, and the resistance value of the resistor is determined by the gating of the fuse. Meanwhile, in order to increase the adjustable range, the trimming unit further includes a first adjustable constant current source 1020 and a second adjustable constant current source 1030; the output end of the first adjustable constant current source 1020 is connected to the output end of the first constant current source 231, and the output end of the second adjustable constant current source 1030 is connected to the output end of the second constant current source 241.
At this time, the adjustable precision and the adjustable range of the RC oscillator depend on the trimming position, fig. 11 shows a variation curve of the output frequency of the RC oscillator along with the trimming position, and if the trimming position is 7fH (i.e. the power of 7 of 2) shown in fig. 11, the process deviation can be controlled within ± 0.25% in an experiment, and the adjustable range is up to ± 32%. When necessary, the zero process deviation can be obtained by increasing the trimming bit number.
In addition, in any of the RC oscillators described above, the first switching device 233 is an N-channel MOS transistor, and a gate, a drain, and a source of the N-channel MOS transistor are respectively a control terminal, an input terminal, and an output terminal of the first switching device 233; the second switching device 243 is an N-channel MOS transistor, and a gate, a drain, and a source of the N-channel MOS transistor are a control terminal, an input terminal, and an output terminal of the second switching device 243, respectively. Of course, the various switching devices may be replaced by other field effect transistors such as junction field effect transistors and bipolar transistors, or may be replaced by triodes, and the details are not repeated here.
The remote controller according to the embodiment of the invention comprises a remote controller chip and an infrared transmitting tube. The output end of the remote controller chip is connected with the negative electrode of the infrared emission tube and used for providing an output signal to the infrared emission tube to serve as a driving electric signal, and the infrared emission tube emits an infrared remote control signal based on the driving electric signal; the RC oscillator according to various embodiments of the present invention described above is integrated in a remote controller chip. In the RC oscillator, one or more of the influence of the temperature coefficient of the resistor on the output frequency of the RC oscillator, the influence of the power coefficient of the capacitor on the output frequency and the influence of the process parameters of the resistor and the capacitor on the output frequency are effectively improved, so that the working performance of the remote controller cannot be reduced while the RC oscillator is integrated into a remote controller chip.
An electrolytic capacitor is usually used in a remote controller to eliminate the large voltage jitter generated by the power supply voltage at the moment when the output pin (OUT pin) of the remote controller is turned on and off (as shown in fig. 4). The instantaneous large voltage jitter will seriously affect the internal logic of the remote controller chip, causing disorder and causing the remote controller chip not to work normally. Therefore, even if the remote controller chip is prepared by adopting a double-crystal double-aluminum process, the electrolytic capacitor cannot be saved.
In order to further completely omit the electrolytic capacitor in the remote controller, the remote controller chip according to the embodiment of the present invention further includes a driving unit, as shown in fig. 12, an input end of the driving unit receives an output signal of the remote controller chip, and an output end of the driving unit is connected to an output end of the remote controller chip to convert the output signal into a driving electrical signal and output the driving electrical signal to an output end (OUT pin) of the remote controller chip. The driving unit comprises a driving inverter 1201 and a driving MOS tube 1202; the input end of the driving inverter 1201 receives an output signal of the remote controller chip, and the output end is connected with the gate of the driving MOS transistor 1202; the drain electrode of the driving MOS tube 1202 is connected with the output end of the remote controller chip, and the source electrode is grounded; and setting the width-length ratio of the driving phase inverter to prolong the opening and closing time of the output end of the remote controller chip.
Those skilled in the art will appreciate that to minimize the on and off times of the output pins of the control chip, the fan-in fan-out coefficients of the device need to be well matched. For example, if a larger device size (width-to-length ratio) is to be driven, for example, to drive the larger-sized driving MOS transistor 1202, the device size, i.e., the size of the driving inverter 1201, needs to be increased to ensure sufficient driving capability to obtain the desired square wave. In the prior art, the width-to-length ratio of the driving inverter 1201 is usually 8 times, even 64 times, of the standard width-to-length ratio, and the driving capability can be ensured by increasing the width-to-length ratio, so that an ideal square wave can be obtained.
However, in the present invention, if the remote controller chip is manufactured using a single crystal single aluminum process, the width-to-length ratio of the driving inverter 1201 is set to be smaller than the standard width-to-length ratio, and preferably, the width-to-length ratio of the 1 driving inverter 1201 may be set to be 0.01 times the standard width-to-length ratio. If a lower-end aluminum gate process is adopted to prepare the remote controller chip, since the driving capability of the device prepared by the process is very weak, and the size of the driving MOS tube 1202 may be more than 1 ten thousand times larger than the standard size, the aspect ratio of the driving inverter 1201 is set to be 0.5-5 times of the standard aspect ratio. In practical application, the appropriate width-to-length ratio of the driving inverter 1201 is selected according to a specific manufacturing process and a specific chip type, as long as the on-time and the off-time of the output end of the remote controller chip can be prolonged.
Taking the width-to-length ratio of the driving inverter 1201 in the single crystal single aluminum process as 0.01 times of the standard width-to-length ratio as an example, the size of the driving inverter is reduced by 800 times or 6400 times compared with the prior art, as shown in fig. 13, as a result, the voltage Vout of the driving electrical signal output by the output pin of the remote controller is not a standard square wave any more, but a trapezoidal wave, and the voltage jump becomes gentle. Because the output pin outputs the trapezoidal wave, the time for opening and closing the output pin (OUT pin) is prolonged, and Vout is not increased or decreased instantly any more, but is increased or decreased slowly. Because the output end voltage Vout of the remote controller chip is changed from square wave to sine wave, the power supply voltage Vdd does not have large jitter shown in FIG. 4 any more, therefore, the internal logic of the remote controller chip is not affected at all, and the signal reception of the receiver is not affected. Meanwhile, the size of the device is greatly reduced. The 0.01 times is used as an example only and is not a limitation to the present invention, and other times, such as 0.02 times, 0.05 times, etc., may be selected in practical applications and are not listed here. The selection of the multiple directly determines the waveform change of Vout, and in the above example, the waveform of Vout after selecting 0.01 times is closer to a sine wave than 0.02 times and 0.05 times.
In addition, in the remote controller according to the embodiment of the present invention, the triode shown in fig. 1 can be omitted by increasing the size of the output pin (OUT pin) to be large enough. Fig. 14 is a schematic diagram showing the structure of a remote controller according to the preferred embodiment of the present invention, in which a transistor and an electrolytic capacitor are omitted and an oscillator is integrated into a remote controller chip, so that a fully built-in remote controller chip is completely implemented, thereby satisfying the current requirements for low cost, high performance and high integration. Preferably, the remote controller chip can be prepared by adopting a single crystal single aluminum process, so that the cost is further reduced.
As can be seen from the above, in the RC oscillator according to the embodiment of the present invention, by providing the temperature coefficient compensation unit including the first well resistance and the second well resistance in the RC oscillator, the slowing of the output frequency caused by the positive temperature coefficient of the reference resistance in the oscillator can be effectively eliminated. By providing an adjustable delay unit comprising a first inverter and a second inverter in the RC oscillator, the output frequency increase caused by the positive supply coefficient of the capacitor can be effectively eliminated. The output frequency drift caused by the drift of the process parameters of the resistor and the capacitor can be eliminated by arranging the trimming unit comprising the trimming resistor in the RC oscillator. Therefore, the various RC oscillators can be integrated into a remote controller chip, the integration level of the remote controller chip is improved, and the cost is reduced while the performance of the device is ensured.
In the remote controller according to the embodiment of the invention, the RC oscillator is integrated in the remote controller chip, so that the integration level of the remote controller is improved, and the size of the remote controller is reduced. By reducing the width-to-length ratio of the driving phase inverter in the remote controller chip, the power supply voltage large-amplitude jitter caused by the instant opening and closing of the output pin can be effectively eliminated, and an electrolytic capacitor can be directly omitted in the remote controller. The remote controller chip can be prepared by adopting a single-crystal single-aluminum process, so that the cost and the preparation difficulty are further reduced.
It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (8)
1. A high precision RC oscillator, comprising:
the device comprises a reference constant current source and a reference resistor, wherein one end of the reference resistor is connected with the output end of the reference constant current source, and the other end of the reference resistor is grounded;
the circuit comprises a first constant current source, a first capacitor and a first switching device, wherein one end of the first capacitor and the input end of the first switching device are respectively connected with the output end of the first constant current source, and the other end of the first capacitor and the output end of the first switching device are respectively grounded;
the circuit comprises a second constant current source, a second capacitor and a second switching device, wherein one end of the second capacitor and the input end of the second switching device are respectively connected with the output end of the second constant current source, and the other end of the second capacitor and the output end of the second switching device are respectively grounded;
a comparison unit and an output inverter, an input end of the comparison unit is connected with an output end of the reference constant current source, an output end of the first constant current source and an output end of the second constant current source, respectively, an output end of the comparison unit is connected with a control end of the first switching device and an input end of the output inverter, respectively, an output end of the output inverter is connected with a control end of the second switching device and an output end of the RC oscillator, respectively, so that the comparison unit compares charging voltages of the first capacitor and the second capacitor with reference voltages output by the reference constant current source, respectively, to generate a control signal based on the comparison, and outputs the control signal to the control end of the first switching device and the control signal to the control end of the second switching device through the output inverter, to control the first and second capacitors to alternately discharge to generate an output signal;
the RC oscillator further comprises a temperature coefficient compensation unit, wherein the temperature coefficient compensation unit comprises a first trap resistor and a second trap resistor; wherein,
one end of the first trap resistor is connected with one end of the first capacitor and the input end of the first switching device respectively, and the other end of the first trap resistor is connected with the output end of the first constant current source;
one end of the second trap resistor is connected with one end of the second capacitor and the input end of the second switching device respectively, and the other end of the second trap resistor is connected with the output end of the second constant current source.
2. The high accuracy RC oscillator of claim 1, further comprising an adjustable delay cell comprising a first inverter and a second inverter; wherein,
the input end of the first phase inverter is connected with the output end of the comparison unit, the output end of the first phase inverter is connected with the input end of the second phase inverter, and the output end of the second phase inverter is respectively connected with the control end of the first switching device and the input end of the output phase inverter;
the first phase inverter is an adjustable-width-to-length-ratio phase inverter.
3. The high accuracy RC oscillator of claim 1, further comprising a trimming unit comprising a trimming resistor; one end of the trimming resistor is connected with the output end of the reference constant current source, and the other end of the trimming resistor is connected with one end of the reference resistor.
4. A high accuracy RC oscillator as claimed in claim 3, wherein the trimming resistor is a fuse resistor.
5. The high accuracy RC oscillator of claim 3, wherein the trimming unit further comprises a first adjustable constant current source and a second adjustable constant current source; the output end of the first adjustable constant current source is connected with the output end of the first constant current source, and the output end of the second adjustable constant current source is connected with the output end of the second constant current source.
6. A high precision RC oscillator according to any one of claims 1 to 5,
the first switch device is an N-channel MOS tube, and a grid electrode, a drain electrode and a source electrode of the N-channel MOS tube are respectively a control end, an input end and an output end of the first switch device;
the second switch device is an N-channel MOS tube, and a grid electrode, a drain electrode and a source electrode of the N-channel MOS tube are respectively a control end, an input end and an output end of the second switch device.
7. A remote controller using the high-precision RC oscillator according to any one of claims 1 to 6, comprising a remote controller chip and an infrared transmitting tube; wherein
The output end of the remote controller chip is connected with the negative electrode of the infrared emission tube and used for providing an output signal to the infrared emission tube to serve as a driving electric signal, and the infrared emission tube emits an infrared remote control signal based on the driving electric signal;
the RC oscillator is integrated in the remote control chip.
8. The remote controller according to claim 7, wherein the remote controller chip comprises a driving unit, an input end of the driving unit receives the output signal of the remote controller chip, and an output end of the driving unit is connected with an output end of the remote controller chip, so as to convert the output signal into the driving electric signal and output the driving electric signal to the output end of the remote controller chip; wherein,
the driving unit comprises a driving phase inverter and a driving MOS tube; the input end of the driving phase inverter receives an output signal of the remote controller chip, and the output end of the driving phase inverter is connected with the grid electrode of the driving MOS tube; the drain electrode of the driving MOS tube is connected with the output end of the remote controller chip, and the source electrode of the driving MOS tube is grounded;
the driving inverter has a width-to-length ratio to extend on and off times of an output terminal of the remote controller chip.
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| KR102610822B1 (en) * | 2016-11-30 | 2023-12-06 | 삼성전자주식회사 | Circuit for controlling oscillator and apparatus including the same |
| CN106877863A (en) * | 2017-02-28 | 2017-06-20 | 江苏芯力特电子科技有限公司 | OSC circuits on a kind of high stability low-power consumption piece |
| CN113285670B (en) * | 2020-12-30 | 2022-12-30 | 思瑞浦微电子科技（苏州）股份有限公司 | Low frequency offset RC oscillator |
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