CN102025346B - Tuner and pre-circuit thereof - Google Patents
Tuner and pre-circuit thereof Download PDFInfo
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- CN102025346B CN102025346B CN200910175018.4A CN200910175018A CN102025346B CN 102025346 B CN102025346 B CN 102025346B CN 200910175018 A CN200910175018 A CN 200910175018A CN 102025346 B CN102025346 B CN 102025346B
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Abstract
The invention discloses a tuner and a pre-circuit thereof. The tuner comprises a plurality of channels, wherein at least one channel comprises a pre-filtering circuit, an amplifier and a tracking filter; the tracking filter comprises a variable capacitor and an inductor; and the variable capacitor and the inductor are coupled to an output end of the amplifier. In addition, in the tuner, at least the amplifier and the variable capacitor are arranged in a complementary metal oxide semiconductor chip. The tuner and the pre-circuit thereof have low manufacturing cost and higher filtering quality.
Description
Technical field
The present invention is about a tuner (tuner), espespecially a kind of by part or all element be made in tuner and the front stage circuits thereof of a silicon.
Background technology
In television system, one of function of tuner is to select needed channel signals the TV signal for the broadband (broadband) from received, then for the selected channel signals going out, carries out follow-up signal and process.Yet conventional tuner is an iron-clad tuner (CAN tuner) at present, it has larger volume.In addition, in tuner, be to come implementation tracking filter to select needed frequency with capacitor and inductor filter, and the electric capacity in tracking filter is a variable capacitance (varactor), yet, because tuner signal to be dealt be broadband (broadband) TV signal (that is, there is very large frequency range), therefore this variable capacitance need to have very large adjustable extent, that is, need very high supply voltage (being approximately greater than 30 volts) to drive this variable capacitance.
In addition, there is at present a kind of silicon tuner to be developed to overcome the shortcoming of above-mentioned iron-clad tuner (variable capacitance that volume is large, needs height is supplied voltage).Yet, although current silicon tuner has advantages of the little and low supply voltage (approximately 3 volts) of volume, but because the tracking filter of silicon tuner need to use active member (active device) to carry out implementation, need consider the factors such as the transduction value (transconductance) of element and noise (noise).Therefore, silicon tuner need to use two-carrier junction transistor (BipolarJunction Transistor, BJT) technique.But by two-carrier junction transistor technique, come implementation silicon tuner can make silicon tuner there is larger chip area, and two-carrier junction transistor technique is also somewhat expensive, therefore cannot really reduces the cost of manufacture of tuner.
In addition, general tuner can have three prime filter circuits, is respectively low-pass filter circuit, bandwidth-limited circuit and high-pass filtering circuit.Yet because considering on cost, these three prime filter circuits only carry out implementation with single capacitor and inductor conventionally, thus, although reduced cost, but there is no high filtering quality.
Summary of the invention
Therefore, one of object of the present invention be to provide a kind of by part or all element be made in the tuner of a silicon, and this tuner has the prime filter circuit of low-cost high filtering quality, to solve the above problems.
According to an aspect of of the present present invention, a kind of front stage circuits of tuner includes a transformer and a plurality of passage.This transformer wherein, for converting single-ended signal to differential wave; And the plurality of passage, include respectively a filter circuit, wherein this filter circuit of the plurality of passage is all directly electrically connected on a node, and this node is an output that is coupled to this transformer.
According to another aspect of the present invention, a kind of tuner includes a plurality of passages, and wherein at least one passage includes a prime filter circuit, a differential amplifier and a tracking filter.This tracking filter includes a variable capacitance and an inductance, and wherein this variable capacitance and this inductance are two outputs that are coupled to this differential amplifier.In addition, in this tuner, at least this amplifier and this variable capacitance are to be arranged in a CMOS (Complementary Metal Oxide Semiconductor) chip (Complementary Metal-Oxide-Semiconductor chip, CMOS chip).
According to another aspect of the present invention, a kind of tuner includes a plurality of passages, and wherein at least one passage includes a prime filter circuit, a differential amplifier and a tracking filter.This tracking filter includes a variable capacitance and an inductance, and wherein this variable capacitance and this inductance are two outputs that are coupled to this differential amplifier.In addition, in this tuner, at least this amplifier and this variable capacitance are to be arranged in a chip, and this inductance is to be external in this chip.
According to tuner of the present invention and front stage circuits thereof, its manufacturing cost can reduce, and has preferably filtering quality.
Accompanying drawing explanation
Fig. 1 is the schematic diagram according to the TV tuner of one embodiment of the invention.
Figure 2 shows that the front stage circuits of tuner can be equivalent to the schematic diagram of a low-pass filter circuit when the selected channel of user is low frequency domain channel.
Fig. 3 is the comparison schematic diagram of the transfer function of the low-pass filter circuit shown in the low-pass filter circuit shown in Fig. 2 and Fig. 1.
Figure 4 shows that the front stage circuits of tuner can be equivalent to the schematic diagram of a high-pass filtering circuit when the selected channel of user is high frequency domain channel.
Fig. 5 is the comparison schematic diagram of the transfer function of the high-pass filtering circuit shown in the high-pass filtering circuit shown in Fig. 4 and Fig. 1.
Figure 6 shows that the front stage circuits of tuner can be equivalent to the schematic diagram of a bandwidth-limited circuit when the selected channel of user is middle frequency domain channel.
Fig. 7 is the comparison schematic diagram of the transfer function of the bandwidth-limited circuit shown in the bandwidth-limited circuit shown in Fig. 6 and Fig. 1.
Fig. 8 corresponds to the installation drawing of the capacitance of each channel for automatically detecting variable capacitance.
When Fig. 9 corresponds to the capacitance of each channel for starting to detect variable capacitance when tuner, the curve chart of the intensity level signal that the capacitance of variable capacitance and signal strength detection unit are exported.
Embodiment
Please refer to Fig. 1, Fig. 1 is the schematic diagram according to the TV tuner 100 of a preferred embodiment of the present invention.As shown in Figure 1, TV tuner 100 includes a transformer 102, a first passage 110, a second channel 120, a third channel 130 and a back end signal treatment circuit 140, and wherein first passage 110 includes two low-pass filter circuit 111_1 and 111_2, two interrupteur SW
1_1and SW
1_2, an attenuator 112, two low noise amplifiers 114 and 116 and one tracking filters 117; Second channel 120 includes two high-pass filtering circuit 121_1 and 121_2, two interrupteur SW
2_1and SW
2_2, an attenuator 122, two low noise amplifiers 124 and 126 and one tracking filters 127; Third channel 130 includes two bandwidth-limited circuit 131_1 and 131_2, four interrupteur SW 3_1, SW3_2, SW3_3, SW3_4, an attenuator 132, two low noise amplifiers 134 and 136 and one tracking filters 137.In addition, low-pass filter circuit 111_1 includes an inductance L
1_1an and capacitor C
1_1; Low-pass filter circuit 111_2 includes an inductance L
1_2an and capacitor C
1_2; High-pass filtering circuit 121_1 includes a capacitor C
2_1an and inductance L
2_1; High-pass filtering circuit 121_2 includes a capacitor C
2_2an and inductance L
2_2; Bandwidth-limited circuit 131_1 includes an inductance L
3_1and two capacitor C
3_1, C
3_3; Bandwidth-limited circuit 131_2 includes an inductance L
3_2and two capacitor C
3_2, C
3_4; Tracking filter 117 includes an inductance L
lBan and variable capacitance 118; Tracking filter 127 includes an inductance L
hBan and variable capacitance 128; Tracking filter 137 includes an inductance L
mBan and variable capacitance 138.
In addition, the TV tuner 100 shown in Fig. 1 is to be made in a printed circuit board (PCB) (Printed Circuit Board, PCB) above, and interrupteur SW
1_1, SW
1_2, SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4, capacitor C
3_1, C
3_3, C
3_2, C
3_4, attenuator 112,122,132, amplifier 114,116,124,126,134,136, variable capacitance 118,128,138 and back end signal treatment circuit 140 be to be made in a chip 150.At the present embodiment, chip 150 is a CMOS (Complementary Metal Oxide Semiconductor) chip (ComplementaryMetal-Oxide-Semiconductor chip, CMOS chip).In addition low-pass filter circuit 111_1,111_2, high-pass filtering circuit 121_1,121_2 and inductance L,
3_1, L
3_2, L
lB, L
hB, L
mBbe to be made in outside chip 150, and be ready-made (off-the-shelf) element.
Tuner 100 shown in Fig. 1 is only one embodiment of the invention, in of the present invention one another embodiment, and inductance L
lB, L
hB, L
mBin at least one inductance can be made in chip 150.In addition, in of the present invention one another embodiment, part in low-pass filter circuit 111_1,111_2, high-pass filtering circuit 121_1,121_2 or bandwidth-limited circuit 131_1,131_2 or all element can also be made in chip 150, and not necessarily will be made in as shown in Figure 1 outside chip 150.In addition the capacitor C in bandwidth-limited circuit 131_1,
3_3, the capacitor C in bandwidth-limited circuit 131_2
3_4and interrupteur SW
3_3, SW
3_4in can also tuner 100 as shown in Figure 1, remove and do not have influence on the operation of tuner 100, the variations in these designs all should be under the jurisdiction of category of the present invention.
One of function of TV tuner 100 is to select needed channel signals the TV signal Vin (frequency range is about 48MHz～850MHz) for the broadband (broadband) from received, then for the selected channel signals going out, carries out follow-up signal and process.For instance, if user uses a teleswitch to select a channel now, and the centre frequency of this channel is 200MHz, TV tuner 100 can be carried out filtering operation to TV signal Vin, so that only there is near signal 200MHz frequency can enter back end signal treatment circuit 140 in TV signal Vin, to carry out follow-up signal, process.And the filtering of TV tuner 100 processing is mainly divided into two stages, first stage is the filtering operation of prime, that is low-pass filter circuit 111_1, 111_2, high-pass filtering circuit 121_1, 121_2 or bandwidth-limited circuit 131_1, the filtering operation that 131_2 carries out, the filtering operation of first stage is mainly that the TV signal Vin of broadband (broadband) is carried out to low pass, high pass or bandpass filtering operation are to produce TV signal after a low-pass filtering, TV signal after TV signal or a bandpass filtering after one high-pass filtering, after these three filtering, TV signal has respectively a plurality of different TV channel signal, second stage is tracking filter operation, that is the filtering operation carried out of tracking filter 117,127,137, the filtering operation of second stage is mainly that TV signal after TV signal or bandpass filtering after TV signal, high-pass filtering after low-pass filtering is carried out to tracking filter operation to produce single television channel signal, for instance, tracking filter 137 can carry out TV signal after bandpass filtering tracking filter and take and obtain the TV channel signal that centre frequency is 200MHz.But in the ordinary course of things,, second stage is followed the trail of the filtering operation SAW filter of can arranging in pairs or groups, cleaner for the target signal filter of target channel adjacent band is obtained, to produce this single television channel signal.
Should be noted, low-pass filter circuit 111_1, high-pass filtering circuit 121_1 and bandwidth-limited circuit 131_1 are output node N who is directly electrically connected on transformer 102
1, and low-pass filter circuit 111_2, high-pass filtering circuit 121_2 and bandwidth-limited circuit 131_2 are output node N who is directly electrically connected on transformer 102
2; In other words, between node N1 and low-pass filter circuit 111_1, high-pass filtering circuit 121_1 and bandwidth-limited circuit 131_1, do not have other element (for example switch element etc.), and node N
2and between low-pass filter circuit 111_2, high-pass filtering circuit 121_2 and bandwidth-limited circuit 131_2, also do not there is other element.In addition, in the embodiment shown in fig. 1, node N
1, N
2respectively as two output nodes of transformer 102, yet, in other embodiments of the invention, node N
1, N
2the output that is coupled to transformer 102, that is, the node N shown in Fig. 1
1, N
2and between transformer 102, can there is other element to exist.
In the operation of tuner 100, first, tuner 100 can first decide the opening of amplifier 114,116,124,126,134,136 and determine switch SW according to the selected channel of user
1_1, SW
1_2, SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4whether conducting.For instance, suppose that its centre frequency of the selected channel of user is 80MHz, that is for tuner 100 be low-frequency channel (that is, need to TV signal Vin ' after transformation, carry out filtering to select this channel with first passage 110), tuner 100 can cut out the amplifier of the amplifier of second channel 120 124,126 and third channel 130 134,136.That is for inputing to TV signal Vin ' after the transformation of first, second, third passage 110,120,130, the amplifier 124,126 of second channel 120 and the amplifier 134,136 of third channel 130 can have great impedance.Therefore, after transformation, TV signal Vin ' can carry out low-pass filtering by low-pass filter circuit 111_1, the 111_2 in first passage 110 under the situation of attenuated signal intensity not, to obtain required signal.In addition, now tuner 100 also can be by interrupteur SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting, and actuating switch SW not
1_1, SW
1_2, because by interrupteur SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting meeting makes the situation that second channel 120 and third channel 130 are signal ground in those switch places.Thus, the front stage circuits of tuner 100 can form two low-pass filter circuits as shown in Figure 2, and the exponent number of two low-pass filter circuits shown in Fig. 2 is higher than the exponent number of low-pass filter circuit 111_1,111_2, therefore, can increase the low-pass filtering quality of tuner 100.Please refer to Fig. 3, Fig. 3 is the comparison schematic diagram of the transfer function (frequency response) of the low-pass filter circuit 111_1 shown in the low-pass filter circuit shown in Fig. 2 and Fig. 1.As shown in Figure 3, solid line is partly the transfer function of the low-pass filter circuit shown in Fig. 2, and dotted line is partly the transfer function of low-pass filter circuit 111_1.Relatively both difference, can know that its transfer function of the low-pass filter circuit shown in Fig. 2 has a recess (notch) in the part of intermediate frequency, and therefore, the signal of intermediate-frequency section has larger decay, and then promotes low-pass filtering quality.
In addition, its centre frequency of the selected channel of the user of take as 750MHz be example, the channel that this frequency is high frequency for tuner 100 (that is, need to TV signal Vin ' after transformation, carry out filtering to select this channel with second channel 120), tuner 100 can cut out the amplifier of the amplifier of first passage 110 114,116 and third channel 130 134,136.That is for inputing to TV signal Vin ' after the transformation of first, second, third passage 110,120,130, the amplifier 114,116 of first passage 110 and the amplifier 134,136 of third channel 130 can have great impedance.Therefore, after transformation, TV signal Vin ' can carry out high-pass filtering by high-pass filtering circuit 121_1, the 121_2 in second channel 120 under the situation of attenuated signal intensity not, to obtain required signal.In addition, tuner 100 also can be by interrupteur SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting, and actuating switch SW not
2_1, SW
2_2, because by interrupteur SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting meeting makes the situation that first passage 110 and third channel 130 are signal ground in these switch places.Thus, the front stage circuits of tuner 100 can form two high-pass filtering circuits as shown in Figure 4, and the exponent number of two high-pass filtering circuits shown in Fig. 4 is than the exponent number of high-pass filtering circuit 121_1,121_2 (order) height, therefore, can increase the high-pass filtering quality of tuner 100.Please refer to Fig. 5, Fig. 5 is the comparison schematic diagram of the transfer function (frequency response) of the high-pass filtering circuit 121_1 shown in the high-pass filtering circuit shown in Fig. 4 and Fig. 1.As shown in Figure 5, solid line is partly the transfer function of the high-pass filtering circuit shown in Fig. 4, and dotted line is partly the transfer function of high-pass filtering circuit 121_1.The difference that compares both, can know that its transfer function of the high-pass filtering circuit shown in Fig. 4 has a recess (notch) (referring to Fig. 5) in the part of low frequency, that is the signal of low frequency part has larger strength retrogression, therefore therefore, high-pass filtering quality also can improve.
In addition, its centre frequency of the selected channel of the user of take as 300MHz be example, the channel that this frequency is intermediate frequency for tuner 100 (that is, need to TV signal Vin ' after transformation, carry out filtering to select this channel with third channel 130), tuner 100 can cut out the amplifier of the amplifier of first passage 110 114,116 and second channel 120 124,126.That is for inputing to TV signal Vin ' after the transformation of first, second, third passage 110,120,130, the amplifier 114,116 of first passage 110 and the amplifier 124,126 of second channel 120 can have great impedance.Therefore, after transformation, TV signal Vin ' can carry out filtering by bandwidth-limited circuit 131_1, the 131_2 in third channel 130 under the situation of attenuated signal intensity not, to obtain required signal.In addition, tuner 100 also can be by interrupteur SW
1_1, SW
1_2, SW
2_1, SW
2_2conducting, and actuating switch SW not
3_1, SW
3_2, SW
3_3, SW
3_4, by interrupteur SW
1_1, SW
1_2, SW
2_1, SW
2_2conducting meeting makes the situation that first passage 110 and second channel 120 are signal ground in these switch places.Thus, the front stage circuits of tuner 100 can form two bandwidth-limited circuits as shown in Figure 6, and the exponent number of two bandwidth-limited circuits shown in Fig. 6 is higher than the exponent number of bandwidth-limited circuit 131_1,131_2, therefore, can increase the bandpass filtering quality of tuner 100.Please refer to Fig. 7, Fig. 7 is the comparison schematic diagram of the transfer function (frequency response) of the bandwidth-limited circuit 131_1 shown in the bandwidth-limited circuit shown in Fig. 6 and Fig. 1.As shown in Figure 7, solid line is partly the transfer function of the bandwidth-limited circuit shown in Fig. 6, and dotted line is partly the transfer function of bandwidth-limited circuit 131_1.Relatively both difference, can know that the bandwidth-limited circuit shown in Fig. 6 has larger frequency range (bandwidth) (referring to Fig. 7), and therefore, the signal of intermediate-frequency section has less strength retrogression, and then promotes bandpass filtering quality.
Take a broad view of the narration of above relevant Fig. 2 to Fig. 7, can know, although in embodiments of the invention, low-pass filter circuit 111_1,111_2, bandwidth-limited circuit 121_1,121_2, high-pass filtering circuit 131_1,131_2 only carry out implementation with simple element, yet, in the embodiment shown in Fig. 1, by opening and the control switch SW of control amplifier 114,116,124,126,134,136
1_1, SW
1_2, SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting state, can allow filter circuit originally utilize the filter circuit element of other passage to reach better filtering quality.At length take low-pass filter circuit 111_1, high-pass filtering circuit 121_1, bandwidth-limited circuit 131_1 illustrates: when channel that the selected channel of user is low frequency, because interrupteur SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting state, therefore, the low-pass filter circuit 111_1 of first passage 110, the capacitor C of second channel 120
2_1and the inductance L of third channel 130
3_1, capacitor C
3_1can form the low-pass filter circuit of high-order as shown in Figure 2; In addition, when channel that the selected channel of user is high frequency, because interrupteur SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting state.Therefore, the high-pass filtering circuit 121_1 of second channel 120 is, the inductance L of first passage 110
1_1and the inductance L of third channel 130
3_1, capacitor C
3_1can form the high-pass filtering circuit of high-order as shown in Figure 4; In addition, when channel that the selected channel of user is intermediate frequency, because interrupteur SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4conducting state.Therefore, the bandwidth-limited circuit 131_1 of third channel 130 is, the inductance L of first passage 110
1_1and the capacitor C of second channel 120
2_1can form the bandwidth-limited circuit of high-order as shown in Figure 6.Therefore,, in embodiments of the invention, can utilize lower-cost filter circuit to reach preferably filtering quality.
After carrying out filtering operation, the prime filter circuit of tuner 110 (filter circuit as shown in Fig. 2, Fig. 4 or Fig. 6) TV signal Vin ' after to transformation can produce signal after a filtering.Afterwards, after filtering, signal can, first via amplifier 114,116,124,126,134 or 136 processing, be selected needed channel by tracking filter 117,127 or 137 afterwards again.Specifically, suppose that the selected channel of user for example, for having the channel of low frequency centre frequency (80MHz), signal after TV signal Vin ' can produce a low-pass filtering after by the low-pass filter circuit filtering shown in Fig. 2 after transformation.Then, if signal has excessive amplitude (intensity) after this low-pass filtering, tuner 100 shutdown amplifiers 114, and make after this low-pass filtering signal first by attenuator 112 by after strength decreased, then amplify to avoid amplifier 116 saturated signal by amplifier 116; Otherwise if the intensity of signal is in permissible range after this low-pass filtering, shutdown amplifier 116, and after making this low-pass filtering, signal directly amplifies signal by amplifier 114.Then, the signal that amplifier 114 or 116 is exported can carry out tracking filter operation to select needed channel signals by tracking filter 117, and the signal that tracking filter 117 is exported afterwards carries out back end signal processing to produce an output signal Vout by back-end processing circuit 140 again.
In the operation at tracking filter 117, tuner 100 can be according to the selected channel of user, decide the capacitance of variable capacitance 118 in tracking filter 117, so that the signal that tracking filter 117 is exported has correct frequency (that is centre frequency of the selected channel of user).The capacitance that variable capacitance 118 corresponds to each channel (for example: when TV has just been started shooting) before system stability decides according to an automatic adjustment mode, for instance, suppose that signal that first passage 110 can be used for exporting 50 channels is to back end signal treatment circuit 140, before system stability, tuner 100 can test out 50 capacitances of variable capacitance 118, and these 50 capacitances make respectively tracking filter 117 can correctly export the signal of these 50 channels.
In addition determining that variable capacitance 118 corresponds to aspect the capacitance of each channel, in embodiments of the invention, be to utilize following mode automatically to detect the capacitance that corresponds to each channel.Please refer to Fig. 8, Fig. 8 corresponds to the installation drawing of the capacitance of each channel for automatically detecting variable capacitance 118.As shown in Figure 8, one frequency generator 810 is coupled to the input of tracking filter 117, one signal strength detection unit 820 is coupled to the output of tracking filter 117, and one adjustment unit 830 be coupled between signal strength detection unit 820 and variable capacitance 118, wherein frequency generator 810, signal strength detection unit 820 and adjustment unit 830 are all made in chip 150.
Please also refer to Fig. 8 and Fig. 9, when Fig. 9 corresponds to the capacitance of each channel for starting to detect variable capacitance 118 when tuner 100, the curve chart of the intensity level signal that the capacitance of variable capacitance 118 and signal strength detection unit 820 are exported.Should be noted, shown in Fig. 9, only for being used for, explain that tuner 100 detects the example explanation that variable capacitance 118 corresponds to the capacitance of each channel, and be not used as restriction of the present invention.Correspond in the operation of capacitance of each channel detecting variable capacitance 118, first, tuner can first cut out amplifier 114 and 116, and variable capacitance 118 now has a default capacitance (C as shown in Figure 9
pre).Afterwards, frequency generator 810 can produce the adjustment signal V with a characteristic frequency
freto the input of tracking filter 117, wherein adjust signal V
frethis characteristic frequency be from the selected taking-up of a plurality of characteristic frequency, and the plurality of characteristic frequency is respectively a plurality of television channel in a television system and distinguishes corresponding a plurality of centre frequencies.Simple example, while supposing that tuner 100 will detect variable capacitance 118 and corresponds to centre frequency and be the capacitance of a channel of 50MHz, frequency generator 810 can produce have the adjustment signal V that characteristic frequency is 50MHz
freinput to tracking filter 117.
At frequency generator 810, can produce the adjustment signal V with characteristic frequency
freto the input of tracking filter 117, tracking filter 117 is exchanged entire signal V
frecarry out filtering operation and adjust signal V after producing a filtering
fil; Afterwards, after signal strength detection unit 820 detection filter, adjust signal V
filintensity level and produce an intensity level signal V
a; Then, adjustment unit 830 is according to intensity level signal V
a(in the embodiment of Fig. 9, the capacitance of variable capacitance 118 is adjusted into C to adjust the capacitance of variable capacitance 118
1).
At adjustment unit 830 according to intensity level signal V
aafter adjusting the capacitance of variable capacitance 118, tracking filter 117 continues to exchange entire signal V
frecarry out filtering operation and adjust signal V after producing filtering
fil, and signal strength detection unit 820 also continues to adjust signal V after detection filter
filintensity level and produce intensity level signal V
a.In addition, after adjustment unit 830, also constantly adjust the capacitance of variable capacitance 118 until adjust signal V after the filtering of 820 of signal strength detection unit
filintensity level (intensity level signal V
a) can be judged as a maximum intensity value till.Figure 9 shows that example, when variable capacitance 118 has capacitance C
ntime, can judge and there is maximum intensity level signal V
a.Therefore, suppose now to adjust signal V
frefrequency be 50MHz, to correspond to centre frequency be that the capacitance of the channel of 50MHz is C to variable capacitance 118
n(that is, when after its centre frequency of the selected channel of user while being 50MHz, the capacitance of variable capacitance 118 can switch to C
n).
Should be noted, find out variable capacitance 118 corresponding to maximum intensity value signal V
athe method flow of capacitance have many kinds, Figure 9 shows that an example of climbing the mountain search method (mountain-climbing search method).Yet, in other embodiments of the invention, also can utilize other search algorithm (for example binary search) to find out variable capacitance 118 corresponding to maximum intensity value signal V
acapacitance, these design on variations all should be under the jurisdiction of category of the present invention.
After getting back to relevant filtering, signal is first by amplifier 114,116,124,126,134 or 136 processing, by tracking filter 117,127 or 137, selected in the narration of needed channel more afterwards, aspect second channel 120, in like manner, suppose that the selected channel of user is the channel with high frequency centre frequency, signal after TV signal Vin ' can produce a high-pass filtering after by the high-pass filtering circuit filtering shown in Fig. 4 after transformation.Then, if signal has excessive amplitude (intensity) after this high-pass filtering, tuner 100 shutdown amplifiers 124, and make after this high-pass filtering signal first by attenuator 122 by after strength decreased, then amplify to avoid amplifier 126 saturated signal by amplifier 126; Otherwise if the intensity of signal is in permissible range after this high-pass filtering, shutdown amplifier 126, and after making this high-pass filtering, signal directly amplifies signal by amplifier 124.Then, the signal that amplifier 124 or 126 is exported can carry out tracking filter operation to select needed channel signals by tracking filter 127, and the signal that tracking filter 127 is exported afterwards carries out back end signal processing to produce output signal Vout by back-end processing circuit 140 again.
As at tracking filter 127 and wherein aspect the adjustment of the capacitance of variable capacitance 128, very similar with the narrating content of above-mentioned relevant tracking filter 117 and variable capacitance 118, in this area, have and conventionally know that the knowledgeable should be able to can recognize tracking filter 127 and the wherein operation of variable capacitance 128 reading the narration of above-mentioned relevant tracking filter 117 and variable capacitance 118, therefore, details does not repeat them here.
In like manner, aspect third channel 130, suppose that the selected channel of user is the channel with intermediate frequency center frequency, signal after TV signal Vin ' can produce a bandpass filtering after by the bandwidth-limited circuit filtering shown in Fig. 6 after transformation, then, if signal has excessive amplitude (intensity) after this bandpass filtering, tuner 100 shutdown amplifiers 134, and after making this bandpass filtering, signal first passes through attenuator 132 by after strength decreased, then amplify to avoid amplifier 136 saturated signal by amplifier 136; Otherwise if the intensity of signal is in permissible range after this bandpass filtering, shutdown amplifier 136, and after making this bandpass filtering, signal directly amplifies signal by amplifier 134.Then, the signal that amplifier 134 or 136 is exported can carry out tracking filter operation to select needed channel signals by tracking filter 137, and the signal that tracking filter 137 is exported afterwards carries out back end signal processing to produce output signal Vout by back-end processing circuit 140 again.
As at tracking filter 137 and wherein aspect the adjustment of the capacitance of variable capacitance 138, it is very similar with the narrating content of above-mentioned relevant tracking filter 117 and variable capacitance 118, in this area, have and conventionally know that the knowledgeable should be able to can recognize tracking filter 137 and the wherein operation of variable capacitance 138 reading the narration of above-mentioned relevant tracking filter 117 and variable capacitance 118, therefore, details does not repeat them here.
In addition, in another embodiment of the present invention, first passage 110, second channel 120, in third channel 130, can only there is an amplifier, that is, amplifier 114, in 116, one of them can remove (if remove amplifier 116 in first passage 110, attenuator 112 also can remove in the lump), amplifier 124, in 126, one of them can remove (if remove amplifier 126 in second channel 120, attenuator 122 also can remove in the lump), and amplifier 134, in 136, one of them can remove (if remove amplifier 136 in third channel 130, attenuator 132 also can remove in the lump), variation in these designs all should be under the jurisdiction of category of the present invention.
In addition, tuner 100 shown in Fig. 1 is full differential architecture (fully differential configuration), that is, transformer 102 is output one differential waves, and first passage 110, second channel 120 and third channel 130 have respectively two filter circuits so that this differential wave (that is, TV signal Vin ' after the transformation shown in Fig. 1) is carried out to filtering.It has been reduction noise jamming (noisecoupling) and harmonic distortion (harmonic distortion) that tuner 100 uses the object of full differential architecture, yet, in another embodiment of the present invention, tuner 100 can also use single-ended framework to save cost, that is low-pass filter circuit 111_2, high-pass filtering circuit 121_2 and bandwidth-limited circuit 131_2 can remove in self-tuner 100, in this area, have and conventionally know that the knowledgeable should be able to be after reading the above-mentioned relevant operation of tuner 100, easily tuner 100 is designed to single-ended framework, therefore, details does not repeat them here.
Concise and to the point conclusion the present invention, in the front stage circuits of tuner of the present invention, only needs to use simple element can reach higher filtering quality; In addition, tuner of the present invention is that most element is made in silicon, therefore has less volume and lower manufacturing cost.
The foregoing is only preferred embodiment of the present invention, all equalizations of doing according to the present patent application the scope of the claims change and modify, and all should belong to covering scope of the present invention.
Claims (9)
1. a tuner, includes:
Transformer, for receiving a single-ended TV signal, and converts this single-ended TV signal to a differential TV signal;
A plurality of passages, for receiving this differential TV signal, each passage includes respectively:
One prime filter circuit, wherein the prime filter circuit of the plurality of passage is all directly electrically connected on a node, and this node is coupled to an output of this transformer;
One differential amplifier, is coupled to this prime filter circuit;
One tracking filter, includes:
One variable capacitance, is coupled to two outputs of this differential amplifier; And
One inductance, is parallel to this variable capacitance;
One frequency generator, be coupled to an input of this tracking filter, be used for producing an adjustment signal to this input of this tracking filter, wherein this adjustment signal has a characteristic frequency, and this tracking filter carries out filtering operation to this adjustment signal adjust signal after producing a filtering;
One signal strength detection unit, is coupled to this tracking filter, is used for detecting an intensity level of adjusting signal after this filtering; And
One adjustment unit, is coupled to this signal strength detection unit, is used for adjusting according to this intensity level of adjusting signal after this filtering the capacitance of this variable capacitance;
Wherein at least this amplifier and this variable capacitance are to be arranged in a CMOS (Complementary Metal Oxide Semiconductor) chip.
2. tuner according to claim 1, is characterized in that, also comprises an attenuator, and it is coupled between this prime filter circuit and differential amplifier.
3. tuner according to claim 1, is characterized in that, this inductance is to be arranged in this CMOS (Complementary Metal Oxide Semiconductor) chip.
4. tuner according to claim 1, is characterized in that, this adjustment unit is constantly adjusted the capacitance of this variable capacitance, until this signal strength detection unit detects the intensity level of adjusting signal after this filtering, can be judged as a maximum intensity value.
5. tuner according to claim 1, it is characterized in that, this frequency generator is chosen this characteristic frequency from a plurality of characteristic frequency and is produced this adjustment signal, and the plurality of characteristic frequency is respectively a plurality of television channel in a television system and distinguishes corresponding a plurality of centre frequencies.
6. a tuner, includes:
A plurality of passages, for receiving a differential TV signal, each passage includes respectively:
One prime filter circuit, wherein the prime filter circuit of the plurality of passage is all directly electrically connected on a node, and this node is used for receiving this differential TV signal;
One amplifier, is coupled to this prime filter circuit;
One tracking filter, includes:
One variable capacitance, is coupled to an output and an earth terminal of this amplifier; And
One inductance, is parallel to this variable capacitance;
One frequency generator, be coupled to an input of this tracking filter, be used for producing an adjustment signal to this input of this tracking filter, wherein this adjustment signal has a characteristic frequency, and this tracking filter carries out filtering operation to this adjustment signal adjust signal after producing a filtering;
One signal strength detection unit, is coupled to this tracking filter, is used for detecting an intensity level of adjusting signal after this filtering; And
One adjustment unit, is coupled to this signal strength detection unit, is used for adjusting according to this intensity level of adjusting signal after this filtering the capacitance of this variable capacitance;
Wherein at least this amplifier and this variable capacitance are to be arranged in a chip, and this inductance is to be external in this chip.
7. tuner according to claim 6, is characterized in that, also comprises an attenuator, and it is coupled between this prime filter circuit and amplifier.
8. tuner according to claim 6, is characterized in that, this adjustment unit is constantly adjusted the capacitance of this variable capacitance, until this signal strength detection unit detects the intensity level of adjusting signal after this filtering, can be judged as a maximum intensity value.
9. tuner according to claim 6, it is characterized in that, this frequency generator is chosen this characteristic frequency from a plurality of characteristic frequency and is produced this adjustment signal, and the plurality of characteristic frequency is respectively a plurality of television channel in a television system and distinguishes corresponding a plurality of centre frequencies.
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| Application Number | Priority Date | Filing Date | Title |
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| CN200910175018.4A CN102025346B (en) | 2009-09-11 | 2009-09-11 | Tuner and pre-circuit thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN200910175018.4A CN102025346B (en) | 2009-09-11 | 2009-09-11 | Tuner and pre-circuit thereof |
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| CN102025346A CN102025346A (en) | 2011-04-20 |
| CN102025346B true CN102025346B (en) | 2014-09-17 |
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| CN104579408B (en) * | 2013-12-19 | 2017-03-29 | 深圳市金溢科技股份有限公司 | Board units OBU and its wake-up receiving circuit |
| US9166638B2 (en) * | 2014-02-14 | 2015-10-20 | Rafael Microelectronics, Inc. | Integrated circuit chip for receiver collecting signals from satellites |
| CN114731170B (en) * | 2019-11-20 | 2023-12-22 | 株式会社村田制作所 | High-frequency module and communication device |
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|---|---|---|---|---|
| CN1309503A (en) * | 2000-02-14 | 2001-08-22 | 夏普公司 | Tuner of cable modem |
| US7088202B2 (en) * | 2003-07-18 | 2006-08-08 | Rfstream Corporation | Methods and apparatus for an improved discrete LC filter |
| CN1901657A (en) * | 2005-07-05 | 2007-01-24 | 三星电子株式会社 | Tuner, broadcast signal processing apparatus comprising the same, and broadcast signal processing method |
| TW200818904A (en) * | 2006-05-21 | 2008-04-16 | Realtek Semiconductor Corp | Multi-band TV tuner and method thereof |
| TW201110543A (en) * | 2009-09-02 | 2011-03-16 | Mstar Semiconductor Inc | Tuner and its front-end circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1309503A (en) * | 2000-02-14 | 2001-08-22 | 夏普公司 | Tuner of cable modem |
| US7088202B2 (en) * | 2003-07-18 | 2006-08-08 | Rfstream Corporation | Methods and apparatus for an improved discrete LC filter |
| CN1901657A (en) * | 2005-07-05 | 2007-01-24 | 三星电子株式会社 | Tuner, broadcast signal processing apparatus comprising the same, and broadcast signal processing method |
| TW200818904A (en) * | 2006-05-21 | 2008-04-16 | Realtek Semiconductor Corp | Multi-band TV tuner and method thereof |
| TW201110543A (en) * | 2009-09-02 | 2011-03-16 | Mstar Semiconductor Inc | Tuner and its front-end circuit |
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| CN102025346A (en) | 2011-04-20 |
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Effective date of registration: 20201022 Address after: No. 1, Xingzhu Road, Hsinchu Science Park, Taiwan, China Patentee after: MEDIATEK Inc. Address before: 405, 4th floor, 1st District, Shenzhen Bay science and technology ecological park, Aohai street, Nanshan District, Shenzhen City, Guangdong Province Patentee before: Mstar Semiconductor,Inc. Patentee before: MEDIATEK Inc. Effective date of registration: 20201022 Address after: 405, 4th floor, 1st District, Shenzhen Bay science and technology ecological park, Aohai street, Nanshan District, Shenzhen City, Guangdong Province Patentee after: Mstar Semiconductor,Inc. Patentee after: MEDIATEK Inc. Address before: 518057, Guangdong, Shenzhen hi tech Zone, South District, science and technology, South ten road, Shenzhen Institute of Aerospace Science and technology innovation, C block, building 4 Patentee before: Mstar Semiconductor,Inc. Patentee before: MSTAR SEMICONDUCTOR Inc. |
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