CN100545779C - High voltage bias PMOS current source circuit - Google Patents

Abstract

A high-voltage bias PMOS current source circuit, comprising: a high-gain operational amplifier circuit; a temperature- and power-independent voltage generation circuit connected to the input end of the high-gain operational amplifier circuit through nodes 2 and 3, thereby realizing clamping output Function; a starting circuit, the output of which is connected to node 2 of the voltage generating circuit independent of temperature and power supply, to prevent the voltage generating circuit having nothing to do with temperature and power supply from entering the dead zone; an output regulating circuit, the output regulating circuit of The input is connected to the node 4 of the voltage generation circuit independent of temperature and power supply, so as to realize the effect of clamping the output, and its output is the output of the whole bandgap reference source circuit; a current source bias circuit, the input of the current source bias circuit It is connected with the output of the output regulation circuit, and the current source bias circuit is composed of a cascode structure current mirror to complete the conversion from voltage to current.

Description

High voltage bias PMOS current source circuit

Technical field

The present invention relates to the current source circuit technique field, particularly a kind ofly be used to provide high voltage bias PMOS current source circuit.

Background technology

The PMOS current source circuit is important unit module in the integrated circuit, is a primary element in analog to digital converter (ADC) and digital to analog converter (DAC) and the telecommunication circuit.Its temperature stability and noise resisting ability are the key factors that influences the conversion accuracy of analog to digital converter (ADC) and digital to analog converter (DAC), even have influence on the precision and the performance of total system.Therefore, good PMOS current source circuit of design is of great practical significance.

The PMOS current source circuit is owing to have a low-temperature coefficient, low supply voltage and can obtain extensive studies and application with advantage such as standard CMOS process compatibility, and its principle is as shown in Figure 1.

The principle of work of PMOS current source circuit is according to the band gap voltage of silicon materials and voltage and the irrelevant characteristic of temperature, utilize the positive temperature coefficient (PTC) of Δ VBE and the negative temperature coefficient of bipolar transistor VBE to cancel out each other, realize that low temperature floats, high-precision reference voltage, producing current source through biasing circuit.If two bipolar transistors are operated under the unequal current density, the difference of their base stage-emitting stage voltage just is directly proportional with absolute temperature so.For example, Q1, Q2 are two identical NPN pipes (IS1=IS2), and collector current is respectively nI0 and I0, ignores the base current influence, can get:

$\mathrm{\&Delta;}{V}_{\mathrm{BE}}=V_{\mathrm{BE}1}-{\mathrm{<figure-callout\; id="2"\; label="V\; BE"\; filenames="C20071009846300152.png,C20071009846300161.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{BE}}=V_T\ln \frac{n{I}_0}{I_{S1}}-V_T\ln \frac{I_0}{{\mathrm{<figure-callout\; id="2"\; label="I\; S"\; filenames="C20071009846300152.png,C20071009846300161.png"\; state="\{\{state\}\}">I</figure-callout>}}_S}=V_T\ln n$

Following formula

$V_T=\frac{\mathrm{KT}}{q},$

K is a Boltzmann constant, and T is an absolute temperature, and q is a unit charge, Δ V _BEJust show positive temperature coefficient (PTC).The temperature drift of two voltages is cancelled out each other, thereby can obtain under a certain temperature, being the voltage reference of zero-temperature coefficient.Through biasing circuit the output of reference voltage is converted to current source.

Summary of the invention

The objective of the invention is to, a kind of high voltage bias PMOS current source circuit that is used to provide is provided, this method is proved by circuit simulation, and on chip, realize, the test result of experiment chip shows: compare with traditional current source circuit, the Adjustable Output Voltage scope of this circuit can reach 0.5V to 1.5V, makes this bias PMOS current source circuit can obtain very high voltage dynamic range, and chip area does not have to increase substantially.

The invention provides a kind of high voltage bias PMOS current source circuit, it is characterized in that, comprising:

One high gain operational amplifying circuit;

The voltage generation circuit of one temperature and supply independent, the voltage generation circuit of this temperature and supply independent is connected with the input end of high gain operational amplifying circuit with 3 by node 2, thereby realizes clamping down on the effect of output;

One start-up circuit, the output of this start-up circuit are connected to the node 2 with the voltage generation circuit of temperature and supply independent, enter the dead band with the voltage generation circuit that prevents temperature and supply independent;

One output regulating circuitry, the input of this output regulating circuitry are connected to the node 4 with the voltage generation circuit of temperature and supply independent, thereby realize clamping down on the effect of output, and it is output as the output of whole band gap reference source circuit;

One current source biasing circuit, the input of this current source biasing circuit is connected with the output of output regulating circuitry, and this current source biasing circuit is made of the cascode structure current mirror, finishes by the conversion of voltage to electric current.

Voltage generation circuit wherein used and temperature and supply independent uses the PNP transistor to constitute.

Wherein used high gain operational amplifying circuit is made up of the two-stage cmos amplifier.

Wherein used two-stage high gain operational amplifying circuit, wherein the first order is the difference input amplifier of the collapsible cascode structure of CMOS, the second level is that single tube MOS amplifier is formed.

The wherein used temperature and the voltage generation circuit of supply independent constitute the Positive and Negative Coefficient Temperature bucking circuit by the bipolar PNP transistor of realizing in four standard CMOS process and constitute.

Wherein the output voltage of its entire circuit is to regulate according to the resistance ratio in this circuit, its relation of regulating by with the resistance of the voltage generation circuit of temperature and supply independent and the ratio decision of the resistance in the output regulating circuitry, its relation of regulating is followed following formula:

VOUT＝(R2/RF2)×V1

Wherein: R2 is that resistance, RF2 are that resistance, V1 are output voltage.

Current source biasing circuit wherein is made of an input operational amplifier and cascode structure current mirror, and the output of operational amplifier is connected to the input of cascode structure current mirror.

Description of drawings

For the effect that makes the convenient simple and direct understanding further feature content of the present invention of auditor and advantage and reached can more manifest, below in conjunction with embodiment and accompanying drawing describe in detail as after, wherein:

Fig. 1 is a conventional P TAT voltage generation circuit;

Fig. 2 is classical band-gap reference circuit;

Fig. 3 is a high voltage bias PMOS current source circuit;

Fig. 4 VREF is with the simulation waveform of temperature, change in voltage;

Fig. 5 complete operation amplifier circuit.

Embodiment

See also shown in Figure 3ly, a kind of high voltage bias PMOS current source circuit of the present invention is characterized in that, comprising:

One high gain operational amplifying circuit 10; Wherein used high gain operational amplifying circuit 10 is made up of the two-stage cmos amplifier;

The voltage generation circuit 20 of one temperature and supply independent, the voltage generation circuit 20 of this temperature and supply independent is connected with the input end of high gain operational amplifying circuit 10 with 3 by node 2, thereby realizes clamping down on the effect of output; Voltage generation circuit 20 wherein used and temperature and supply independent uses the PNP transistor to constitute; Wherein used temperature and the voltage generation circuit of supply independent 20 constitute the Positive and Negative Coefficient Temperature bucking circuit by the bipolar PNP transistor of realizing in four standard CMOS process and constitute;

One start-up circuit 30, the output of this start-up circuit 30 are connected to the node 2 with the voltage generation circuit 20 of temperature and supply independent, enter the dead band with the voltage generation circuit 20 that prevents temperature and supply independent;

One output regulating circuitry 40, the input of this output regulating circuitry 40 are connected to the node 4 with the voltage generation circuit 20 of temperature and supply independent, thereby realize clamping down on the effect of output, and it is output as the output of whole band gap reference source circuit;

One current source biasing circuit 50, the input of this current source biasing circuit 50 is connected with the output of output regulating circuitry 40, and this current source biasing circuit is made of the cascode structure current mirror, finishes by the conversion of voltage to electric current; Current source biasing circuit 50 wherein is made of an input operational amplifier and cascode structure current mirror, and the output of operational amplifier is connected to the input of cascode structure current mirror.

Wherein used two-stage high gain operational amplifying circuit 10, wherein the first order is the difference input amplifier of the collapsible cascode structure of CMOS, the second level is that single tube MOS amplifier is formed.

Wherein the output voltage of its entire circuit is to regulate according to the resistance ratio in this circuit, its relation of regulating by with the resistance 60 of the voltage generation circuit 20 of temperature and supply independent and the ratio decision of the resistance 70 in the output regulating circuitry 40, its relation of regulating is followed following formula:

VOUT＝(R2/RF2)×V1

Wherein: R2 is that resistance 70, RF2 are that resistance 60, V1 are output voltage.

According to Fig. 1, the principle of work of band-gap reference is according to the band gap voltage of silicon materials and voltage and the irrelevant characteristic of temperature, utilize the positive temperature coefficient (PTC) of Δ VBE and the negative temperature coefficient of bipolar transistor VBE to cancel out each other, realize that low temperature floats, high-precision reference voltage.If two bipolar transistors are operated under the unequal current density, the difference of their base stage-emitting stage voltage just is directly proportional with absolute temperature so.Obtain exporting Vref ≈ 1.22V.Too high for supply voltage, be difficult to utilize cascode structure to duplicate accurately in consequent electric current and use to the back level.

According to the classical band-gap reference circuit of Fig. 2, because the junction voltage of forward biased PN junction has negative temperature coefficient, during T ≈ 300K, Therefore, utilize the voltage of positive and negative temperature coefficient can design the benchmark of a gratifying zero-temperature coefficient.

A desirable burning voltage should satisfy:

1, voltage is subjected to Temperature Influence very little, and very little temperature coefficient is promptly arranged;

2, it is very little that voltage is subjected to the influence of supply voltage VDD, and higher Power Supply Rejection Ratio is promptly arranged.

The principle of band gap voltage as shown in Figure 1, if two bipolar transistors are operated under the unequal current density, the difference of their base stage-emitting stage voltage just is directly proportional with absolute temperature so.For example, transistor Q1, Q2 are two identical NPN pipes (IS1=IS2), and collector current is respectively nI0 and I0, ignores the base current influence, can get:

$\mathrm{\&Delta;}{V}_{\mathrm{BE}}=V_{\mathrm{BE}1}-{\mathrm{<figure-callout\; id="2"\; label="V\; BE"\; filenames="C20071009846300152.png,C20071009846300161.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{BE}}=V_T\ln \frac{n{I}_0}{I_{S1}}-V_T\ln \frac{I_0}{{\mathrm{<figure-callout\; id="2"\; label="I\; S"\; filenames="C20071009846300152.png,C20071009846300161.png"\; state="\{\{state\}\}">I</figure-callout>}}_S}=V_T\ln n$

Following formula $V_T=\frac{\mathrm{KT}}{q},$ K is a Boltzmann constant, and T is an absolute temperature, and q is a unit charge, Δ V _BEJust show positive temperature coefficient (PTC):

$\frac{\&PartialD;\mathrm{\&Delta;}{V}_{\mathrm{BE}}}{\&PartialD;T}=\frac{k}{q}\ln n$

Because the junction voltage of forward biased PN junction has negative temperature coefficient, during T ≈ 300K,

Therefore, utilize the voltage of positive and negative temperature coefficient can design the benchmark of a gratifying zero-temperature coefficient.Classical band-gap reference circuit is as shown in Figure 2:

Transistor QN, Q1 are parasitic longitudinal P NP triode in the CMOS technology, and transistor QN is made of the parallel connection of 8 PNP pipes.Operational amplifier is clamped down on the voltage of 2,3 of nodes, makes the voltage at these two ends equate i.e. (3):

I ₀·R ₁+V _BEN＝V _BE1

Wherein I0 is the electric current that flows through resistance R 1, according to following formula V is arranged _BE1-V _BEN=V _TSo ln n is I ₀=V _TLn n/R ₁, electric current duplicates by metal-oxide-semiconductor p1 and p3, makes following formula set up

$V_{\mathrm{REF}}=V_{\mathrm{BE}}+I_0\&CenterDot;R2=V_{\mathrm{BE}}+\frac{R_2}{R_1}{V}_T\ln n$

Can obtain the very little burning voltage of temperature coefficient by the ratio of adjusting resistance, the technology library of the 0.35 μ m that utilization special permission semiconductor (Chartered) provides, emulation in HSPICE, obtain exporting Vref ≈ 1.22V, when temperature changes in-20-100 ℃ scope, Δ Vref ≈ 0.8mV, the maximum temperature coefficient is about 15ppm/ ℃; When supply voltage VDD changes in the 2.9V-3.7V scope, Δ Vref ≈ 0.7mV.

Yet by the current/charge-voltage convertor of back as can be known, the voltage 1.22V that utilizes this structure to produce is too high with respect to the supply voltage of 3.3V, is difficult to utilize cascode structure to duplicate accurately to the back level in consequent electric current and uses.Utilize circuit shown in Figure 3 just can produce reference voltage less than 1V, and utilize that cascode structure duplicates accurately to current source.

Wherein, resistance R F1=RF2, the voltage that operational amplifier A is clamped down on node 2,3 makes it equal.The dotted line left side is a start-up circuit, prevents that the Bandgap circuit working from being zero working point at electric current, and metal-oxide-semiconductor S plays the effect of a diode.When core circuit when to be operated in electric current be zero working point, the voltage that node S1 order is higher than the voltage of node 2, and S manage conducting, starts to transistor Q1 to charge, and makes the core circuit conducting, the working point of disengaging zero current.

If resistance R F=RF1=RF2.Flow through the electric current separated into two parts of metal-oxide-semiconductor P1: a part flows through resistance R F2, and another part flows through R1, so total current is

$I_0=\frac{V_{\mathrm{BE}}}{R_F}+\frac{V_T}{R_1}\ln n$

Metal-oxide-semiconductor P3 duplicates P1 tube current, output voltage

$V_{\mathrm{REF}}={\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="C20071009846300152.png,C20071009846300161.png"\; state="\{\{state\}\}">R</figure-callout>}}_2\&CenterDot;I_0=\frac{R_2}{R_F}(V_{\mathrm{BE}}+\frac{R_F}{R_1}{V}_T\ln n)$

In following formula, expression is bandgap voltage reference in the bracket, obviously, can select suitable voltage by the ratio of adjusting resistance 60, resistance 70.

The present invention is a kind of high voltage bias PMOS current source circuit (Fig. 3) that is applied to analog to digital converter (ADC) and digital to analog converter (DAC), comprise: high gain operational amplifying circuit 10, voltage generation circuit 20 with temperature and supply independent, start-up circuit 30, output regulating circuitry 40 and current source biasing circuit 50.Because under low-voltage technology, the output voltage of conventional voltage reference source circuit is to be difficult to adapt to requirement about 1.22V, so need design the more reference source of low output voltage.Wherein operational amplification circuit 10 example as shown in Figure 5, form by two-stage amplifier, the first order is the difference input amplifier of collapsible cascode structure, and the second level is that single tube MOS amplifier is formed, and it mainly is the effect of playing computing and clamping down on voltage.Constitute and constitute the Positive and Negative Coefficient Temperature bucking circuit with the voltage generation circuit 20 of temperature and supply independent by the bipolar transistor of realizing in four standard CMOS process, this circuit has also comprised start-up circuit.This circuit provides an exportable and traditional magnitude of voltage that becomes some ratios with the voltage generation circuit output voltage of temperature and supply independent of resistance ratio output circuit, and this ratio is regulated by the design of the ratio of resistance 60 and resistance 70.

Described high gain operational amplifying circuit 10 is made up of the two-stage cmos amplifier, and its gain is greater than 90dB.Voltage generation circuit used and temperature and supply independent uses the PNP triode to constitute.

Described two-stage high gain operational amplifying circuit 10, wherein the first order is the difference input amplifier of the collapsible cascode structure of CMOS, the second level is that single tube MOS amplifier is formed.

The voltage generation circuit 20 of described temperature and supply independent constitutes the Positive and Negative Coefficient Temperature bucking circuit by the bipolar transistor of realizing in four standard CMOS process (PNP) and constitutes.

Described output voltage can provide a resistance ratio to regulate according to this circuit, its relation of regulating by with the ratio decision of two resistance 60 and the resistance 70 of the voltage generation circuit 20 of temperature and supply independent.

Described its output voltage can provide a resistance ratio to regulate according to this circuit, and its relation of regulating is determined by formula VOUT=(R2/RF2) * V1.Reference voltage V1 is the output voltage of traditional benchmark source circuit.

Fig. 4 is the simulation waveform of VREF with temperature, change in voltage.

Below introducing the design of operational amplification circuit, this circuit all is two-stage calculation amplifiers, the first order is collapsible cascode structure, the second level all is made up of single tube MOS amplifier, Fig. 5 is an embodiment who uses the circuit of the operational amplifier among the present invention, among the figure, the dotted line left side is a biasing circuit.What metal-oxide-semiconductor P8, P10 adopted is the low-voltage cascode structure, and capacitor C C is a building-out capacitor, in order to the phase margin of compensation amplifier.Its size approximately equates with load capacitance.

Claims (2)

1. A high voltage bias PMOS current source circuit, characterized in that it comprises: A high-gain operational amplifier circuit is composed of two-stage CMOS amplifiers. The first stage of the two-stage CMOS amplifier is a differential input amplifier with a COMS folded cascode structure, and the second stage is a single-transistor MOS amplifier; A temperature- and power-independent voltage generating circuit, which is composed of a positive and negative temperature coefficient offset circuit formed by four bipolar PNP transistors implemented in a standard CMOS process. The temperature- and power-independent voltage generating circuit is connected to the The input terminal of the high-gain operational amplifier circuit is connected to realize the function of clamping the output; A start-up circuit consisting of four bipolar PNP transistors implemented in a standard CMOS process, the output of which is connected to node 2 of the temperature- and power-independent voltage generation circuit to prevent the temperature- and power-independent voltage generation circuit from into the dead zone; An output regulation circuit, formed by a bipolar PNP transistor implemented in a standard CMOS process, the input of the output regulation circuit is connected to the node 4 of the voltage generation circuit independent of temperature and power supply, thereby realizing the effect of clamping the output; A current source bias circuit, the input of the current source bias circuit is connected to the output of the output regulation circuit, the current source bias circuit is composed of an input operational amplifier and a cascode structure current mirror, and the output of the operational amplifier is connected to The input of the cascode structure current mirror, the current source bias circuit completes the conversion from voltage to current. 2. The high-voltage bias PMOS current source circuit according to claim 1, wherein the output voltage of the high-voltage bias PMOS current source circuit is adjusted according to the resistance ratio in the circuit, and the adjustment relationship is determined by temperature The ratio of the resistance of the voltage generation circuit independent of the power supply to the resistance of the output adjustment circuit is determined, and the adjustment relationship follows the following formula: VOUT＝(R2/RF2)×V1 Among them: R2 is the resistance of the output regulating circuit, RF2 is the resistance of the voltage generating circuit independent of temperature and power supply, V1 is the output voltage of the voltage generating circuit independent of temperature and power supply, VOUT is the output voltage of the output regulating circuit.

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