CN100471051C - Low voltage negative feedback transconductance amplifier - Google Patents

Abstract

This invention relates to a low voltage negative feed back transconductance amplifier characterizing that it combines the advantages of current negative feedback, overturn voltage follower and source attenuation to overcome the shortcomings of small input amplitude, poor linearity not suitable for low voltage, this invented current negative feedback module increases the input amplitude of the transconductance amplifier, the low resistance node of the overturn voltage follower module combined with the source attenuation structure reduces distortion brought with the traditional source attenuation, and the introduction of the low resistance node brings free design to circuit.

Description

A kind of low voltage negative feedback transconductance amplifier

Technical field

The invention belongs to the VLSI (very large scale integrated circuit) designs in Microelectronics and Solid State Electronics field, relate to a kind of novel mutual conductance amplifying circuit, can be used for analog signal processing circuit, Gm-C filter, the design of analog to digital conversion circuit and variable gain amplifier etc.

Background technology

Trsanscondutance amplifier is the important composition module of analog circuit, is widely used in analog signal processing circuit, and the Gm-C filter is in analog to digital conversion circuit and the variable gain amplifier.Trsanscondutance amplifier also is applied to being operated in the sampling mixting circuit of intermediate frequency even radio frequency recently.In these circuit, the linearity of whole system is often determined by trsanscondutance amplifier.Though in disclosed document, proposed to import as cross-couplings multichannel difference, the source class decay, substrate drives, the method of the multiple raising trsanscondutance amplifier linearities such as balance pseudo-differential structure, but because these methods are subjected to the influence of transistor internal nonlinearity and other factors, its total harmonic distortion (THD) generally all-40dB～-60dB, and its input range is also far away under supply voltage.

Therefore design one and can be operated under the low-voltage, the high-performance trsanscondutance amplifier with high linearity and big input range has just become present Analog Circuit Design to be badly in need of one of subject matter that solves.

At this situation, the invention provides a kind of Current Negative Three-Point Capacitance that combines, the novel transconductance amplifier circuit of turnover voltage follower and three kinds of technological merits of source class decay.

Summary of the invention

The object of the present invention is to provide to have high linearity and big input range when can overcome above-mentioned shortcoming, but the transconductance amplifier circuit of low voltage operating.

The present invention uses feedback resistance to constitute a Current Negative Three-Point Capacitance.The effect of this resistance is to force a part of alternating voltage to drop on this resistance by current feedback, significantly reduce to be added in the voltage on the input pipe M1/M2, thereby reduce the generation of nonlinear terms, simultaneously the linear input range of trsanscondutance amplifier is mentioned the level that is higher than supply voltage.

The mutual conductance expressed intact formula of this trsanscondutance amplifier is:

$G_m=\frac{{\mathrm{kg}}_{m1}}{1/r_{o1}{g}_{m3}+g_{m1}({\mathrm{kR}}_{\mathrm{in}}+R_S/2)}$

G wherein _M1Be the mutual conductance of M1 pipe, r _O1Be the output resistance of M1 pipe, g _M3Be the mutual conductance of M3 pipe, k is the bias current ratio of M1 pipe place path and M7 pipe place path.R _InBe feedback resistance, R _SIt is the source class damping resistance.Owing to used the turnover voltage follower, the output resistance of this follower is:

$R_{\mathrm{out}}=\frac{1}{g_{m1}{g}_{m3}{r}_{o1}}$

Little output resistance can significantly be eliminated the distortion that the source class attenuating structure is introduced.Owing to be added in upset follower V _GsOn pressure drop be a fixed voltage, so input signal passed to source class by the accurate grid from input pipe M1/M2, and can introduce distortion unlike traditional structure, improved the linearity.Another benefit that this circuit brings is to make formula 1/r _O1g _M3＜＜g _M1(kR _In+ R _S/ 2) be easier to set up.Therefore given circuit design bigger design freedom.And need be in transconductance value unlike traditional structure, bias current is traded off between the output resistance.Therefore the expression formula of this trsanscondutance amplifier can be reduced to:

$G_m\≈\frac{1}{R_m+R_S/2k}$

Transconductance value is fully by feedback resistance as can be seen, and source class damping resistance and current ratio are controlled.Therefore this circuit can reach high transconductance linearity degree.Pass through feedback resistance R in addition _InThe modification of value can obtain various transconductance value.

The invention is characterized in and contain:

4 N type metal-oxide-semiconductors: the first metal-oxide-semiconductor M1, the second metal-oxide-semiconductor M2, the 3rd metal-oxide-semiconductor M3, the 4th metal-oxide-semiconductor M4 has constituted two turnover voltage followers, and wherein the grid of the first metal-oxide-semiconductor M1 connects the first feedback resistance R through first node 11 _Inp, the first feedback resistance R _InpThe other end meet the first input voltage V through Section Point 110 _Inp, the grid of the second metal-oxide-semiconductor M2 connects the second feedback resistance R through the 3rd node 21 _Inn, the second feedback resistance R _InnThe other end meet the second input voltage V through the 4th node 210 _InnThe first feedback resistance R _Inp, the second feedback resistance R _InnForce the part of input voltage to be added in the first feedback resistance R by current feedback _Inp, the second feedback resistance R _InnOn, thereby reduce to be added in voltage on the first metal-oxide-semiconductor M1, the second metal-oxide-semiconductor M2, reduce the generation of nonlinear terms, simultaneously the input range of trsanscondutance amplifier is brought up to the level of supply voltage; The drain electrode of the source class of the first metal-oxide-semiconductor M1 and the 3rd metal-oxide-semiconductor M3 is connected in the 5th node 12; The drain electrode of the source class of the second metal-oxide-semiconductor M2 and the 4th metal-oxide-semiconductor M4 is connected in the 6th node 22; Between the 5th node 12 and the 6th node 22, connecting a source class damping resistance R _S, the distortion of being introduced with the decay of remarkable minimizing source class;

Current mirror is by 8 N type metal-oxide-semiconductors: the 5th metal-oxide-semiconductor M5, the 6th metal-oxide-semiconductor M6, the 11 metal-oxide-semiconductor M11, the 12 metal-oxide-semiconductor M12, the 13 metal-oxide-semiconductor M13, the 14 metal-oxide-semiconductor M14, the 15 metal-oxide-semiconductor M15, the 16 metal-oxide-semiconductor M16 constitute, the source class ground connection of the 13 metal-oxide-semiconductor M13, the 5th metal-oxide-semiconductor M5, the 6th metal-oxide-semiconductor M6, the 14 each pipe of metal-oxide-semiconductor M14 wherein, the grid of the 15 metal-oxide-semiconductor M15 and the 11 metal-oxide-semiconductor M11 is connected offset signal through the 7th node 15 jointly; The grid of the 16 metal-oxide-semiconductor M16 and the 12 metal-oxide-semiconductor M12 is connected offset signal through the 8th node 25 jointly, the grid while of the 13 metal-oxide-semiconductor M13 and the 5th metal-oxide-semiconductor M5 and the grid of the 4th metal-oxide-semiconductor M4, the drain electrode of the second metal-oxide-semiconductor M2 is connected in the 9th node 23, the grid while of the 14 metal-oxide-semiconductor M14 and the 6th metal-oxide-semiconductor M6 and the grid of the 3rd metal-oxide-semiconductor M3, the drain electrode of the first metal-oxide-semiconductor M1 is connected in protelum point 13, the source electrode of the 15 metal-oxide-semiconductor M15 and the drain electrode of the 13 metal-oxide-semiconductor M13 are connected in the 11 node 18, the drain electrode of the source class of the 11 metal-oxide-semiconductor M11 and the 5th metal-oxide-semiconductor M5 is connected in the 12 node 17, the drain electrode of the source class of the 12 metal-oxide-semiconductor M12 and the 6th metal-oxide-semiconductor M6 is connected in the source electrode of the 13 node 27, the 16 metal-oxide-semiconductor M16 and the drain electrode of the 14 metal-oxide-semiconductor M14 is connected in the 14 node 28; In addition, the drain electrode of the 11 metal-oxide-semiconductor M11 and the 12 metal-oxide-semiconductor M12 links to each other with the 3rd node 21 with first node 11 respectively successively;

The current source load circuit is by 6 P type metal-oxide-semiconductors: the 7th metal-oxide-semiconductor M7, the 8th metal-oxide-semiconductor M8, the 9th metal-oxide-semiconductor M9, the tenth metal-oxide-semiconductor M10, the 17 metal-oxide-semiconductor M17, the 18 metal-oxide-semiconductor M18 constitute, wherein, the source electrode of the 7th metal-oxide-semiconductor M7, the 8th metal-oxide-semiconductor M8, the 9th metal-oxide-semiconductor M9, the tenth metal-oxide-semiconductor M10, the 17 metal-oxide-semiconductor M17, the 18 each pipe of metal-oxide-semiconductor M18 meets power supply V _DdThe grid of the 7th metal-oxide-semiconductor M7, the 8th metal-oxide-semiconductor M8, the 9th metal-oxide-semiconductor M9, the tenth metal-oxide-semiconductor M10, the 17 metal-oxide-semiconductor M17, the 18 each pipe of metal-oxide-semiconductor M18 is connected in the 15 node 14, the 15 node 14 external biasing circuits are to provide the static direct current electric current of current source load circuit, the drain electrode of the 7th metal-oxide-semiconductor M7 and the tenth metal-oxide-semiconductor M10 links to each other with the 3rd node 21 with first node 11 respectively successively, the drain electrode of the 17 metal-oxide-semiconductor M17 and the drain electrode of the 15 metal-oxide-semiconductor M15 are connected in the 16 node 19, constitute the second output node i _On, the drain electrode of the 18 metal-oxide-semiconductor M18 and the drain electrode of the 16 metal-oxide-semiconductor M16 are connected in the 17 node 29, constitute the first output node i _Op

2 P type metal-oxide-semiconductors: the 19 metal-oxide-semiconductor Mp8 and the 20 metal-oxide-semiconductor Mp9, the source class of these 2 metal-oxide-semiconductors meets power supply V _DdAnd grid connects the 18 node 16 after linking to each other, the 18 node 16 is the Voltage Feedback point of common mode feedback circuit, and the drain electrode of the 19 metal-oxide-semiconductor Mp8 links to each other with the drain electrode of the 8th metal-oxide-semiconductor M8 in the current source load circuit after protelum point 13 links to each other with the drain electrode of the first metal-oxide-semiconductor M1; The drain electrode of the 20 metal-oxide-semiconductor Mp9 links to each other with the drain electrode of the 9th metal-oxide-semiconductor M9 in the current source load circuit after the drain electrode of the second metal-oxide-semiconductor M2 in the 9th node 23 and the turnover voltage follower links to each other, so that will convert the common-mode point of regulating the current source load circuit behind the current signal from the voltage signal that common mode feedback circuit feeds back to.

The trsanscondutance amplifier of invention combines Current Negative Three-Point Capacitance, the advantage of turnover voltage follower and three kinds of technology of source class decay, and it is little to have overcome traditional trsanscondutance amplifier input range, and poor linearity is not suitable for shortcomings such as low voltage operating.This circuit is through emulation testing, under 0.18 micrometre CMOS process, under the 1.5V supply power voltage.Difference input 2V peak-to-peak amplitude and 100MHz frequency signal, its total harmonic distortion (THD) is about-79dB, and power consumption only is a microwatt more than 200.

The maximum pressure drop of this circuit on critical path only is V in addition _Gs+ 2V _DsatThereby, demonstrate the potentiality of under low-voltage more, working.After tested, this circuit can well be worked under 0.18 micrometre CMOS process 1.2V supply power voltage.And the supply power voltage of this circuit also has the space that further reduces.

Description of drawings

Fig. 1. transconductance amplifier circuit figure of the present invention.

Embodiment

Technical solution of the present invention is consulted Fig. 1.Fig. 1 is the big input range low-voltage of a high linearity transconductance amplifier circuit structure chart.3 resistance R _Inp, R _Inn, R _S, wherein feedback resistance is R _Inp, R _Inn, feedback resistance one end links to each other with input, the grid level of another termination M1 M2, and the source class damping resistance is R _S, be connected between M1 and the M2 tube source grade.4 N type metal-oxide-semiconductor M1, M2, M3, M4 have constituted two turnover voltage followers.Current source load constitutes with 6 P type metal-oxide-semiconductors: M7, M8, M9, M10, M17, M18.Current source constitutes with 8 N type metal-oxide-semiconductors: M5, M6, M11, M12, M13, M14, M15, M16.2 P type metal-oxide-semiconductor Mp8, Mp9 will feed back the voltage signal that feeds back from common mode feedback circuit and convert current signal to, the output common mode point of regulating circuit.

The concrete annexation of low voltage negative feedback transconductance amplifier is: 110 nodes and 210 nodes are 2 signal input nodes.Feedback resistance R _InpOne terminated nodes, 110, one terminated nodes 11.Feedback resistance R _InnOne terminated nodes, 210, one terminated nodes 21.The source electrode of transistor M7, M8, M9, M10, M17, M18 links to each other with power supply, and grid links to each other with node 14, and node 14 external biasing circuits provide the static direct current electric current of circuit.The drain electrode of transistor M17, M18 respectively with node 19, node 29 links to each other.Node 19, node 29 is the output node of entire circuit.Transistor Mp8, Mp9 source electrode link to each other with supply voltage, and grid connects node 16, and drain electrode connects node 13 and node 23 respectively.Node 16 is a common mode feedback circuit Voltage Feedback point.Transistor M1 grid connects node 11, and source electrode connects node 12, and drain electrode connects node 13.Transistor M2 grid connects node 21, and source electrode connects node 22, and drain electrode connects node 23.Source electrode damping resistance R _SOne end connects node 12, one ends and connects node 22.Transistor M3 drain electrode connects node 12, and grid connects node 13, source ground.Transistor M4 drain electrode connects node 22, and grid connects node 23, source ground.Transistor M11, M15 grid connect node 15.The voltage of node 15 comes auto bias circuit.Transistor M11 drain electrode connects node 11, and source electrode connects node 17.Transistor M15 drain electrode connects node 19, and source electrode connects node 18.Transistor M5, M13 source ground, grid connects node 23.Transistor M5 drain electrode connects node 17.Transistor M13 drain electrode connects node 18.Transistor M12, M16 grid connect node 25.The voltage of node 25 comes auto bias circuit.Transistor M12 drain electrode connects node 21, and source electrode connects node 27.Transistor M16 drain electrode connects node 29, and source electrode connects node 28.Transistor M6, M14 source ground, grid connects node 13.Transistor M6 drain electrode connects node 27.Transistor M14 drain electrode connects node 28.

Feedback resistance R _Inp, R _InnForce an alternating voltage part to be added on this resistance by current feedback, thereby reduce to be added in the voltage on the input pipe M1/M2, reduce the generation of nonlinear terms, simultaneously the input range of trsanscondutance amplifier is brought up to the level that is higher than supply voltage.And transistor M1, M2, M3, M4 constitute two upset followers and add source electrode damping resistance R _SThe structure that constitutes is brought 2 Low ESR output nodes 12,22.Low output resistance can significantly reduce the distortion that the source class attenuating structure is introduced.Owing to be added in upset follower V _GsOn pressure drop be a fixed voltage, so input signal passed to source class by the accurate grid from input pipe M1/M2, unlike traditional structure because V _GsDo not fix and the introducing distortion.The maximum pressure drop of circuit on critical path only is V _Gs+ 2V _DsatThereby, demonstrate the potentiality that this circuit is worked under low-voltage more.More than various technology combine and just realized a high linearity, big input range is fit to the high-performance low voltage negative feedback transconductance amplifier circuit of low voltage operating.

Claims (1)

1. low voltage negative feedback transconductance amplifier is characterized in that containing:

4 N type metal-oxide-semiconductors: first metal-oxide-semiconductor (M1), second metal-oxide-semiconductor (M2), the 3rd metal-oxide-semiconductor (M3), the 4th metal-oxide-semiconductor (M4) has constituted two turnover voltage followers, and wherein the grid of first metal-oxide-semiconductor (M1) connects the first feedback resistance (R through first node (11) _Inp), the first feedback resistance (R _Inp) the other end through Section Point (110) meet the first input voltage (V _Inp), the grid of second metal-oxide-semiconductor (M2) connects the second feedback resistance (R through the 3rd node (21) _Inn), the second feedback resistance (R _Inn) the other end meet the second input voltage (V through the 4th node (210) _Inn); First feedback resistance (the R _Inp), the second feedback resistance (R _Inn) force the part of input voltage to be added in the first feedback resistance (R by current feedback _Inp), the second feedback resistance (R _Inn) on, thereby reduce to be added in voltage on first metal-oxide-semiconductor (M1), second metal-oxide-semiconductor (M2), reduce the generation of nonlinear terms, simultaneously the input range of trsanscondutance amplifier is brought up to the level of supply voltage; The drain electrode of the source class of first metal-oxide-semiconductor (M1) and the 3rd metal-oxide-semiconductor (M3) is connected in the 5th node (12); The drain electrode of the source class of second metal-oxide-semiconductor (M2) and the 4th metal-oxide-semiconductor (M4) is connected in the 6th node (22); Between the 5th node (12) and the 6th node (22), connecting a source class damping resistance (R _S), the distortion of being introduced with the decay of remarkable minimizing source class;

Current mirror is by 8 N type metal-oxide-semiconductors: the 5th metal-oxide-semiconductor (M5), the 6th metal-oxide-semiconductor (M6), the 11 metal-oxide-semiconductor (M11), the 12 metal-oxide-semiconductor (M12), the 13 metal-oxide-semiconductor (M13), the 14 metal-oxide-semiconductor (M14), the 15 metal-oxide-semiconductor (M15), the 16 metal-oxide-semiconductor (M16) constitute, the source class ground connection of the 13 metal-oxide-semiconductor (M13), the 5th metal-oxide-semiconductor (M5), the 6th metal-oxide-semiconductor (M6), each pipe of the 14 metal-oxide-semiconductor (M14) wherein, the grid of the 15 metal-oxide-semiconductor (M15) and the 11 metal-oxide-semiconductor (M11) is connected offset signal through the 7th node (15) jointly; The grid of the 16 metal-oxide-semiconductor (M16) and the 12 metal-oxide-semiconductor (M12) is connected offset signal through the 8th node (25) jointly, the grid while of the 13 metal-oxide-semiconductor (M13) and the 5th metal-oxide-semiconductor (M5) and the grid of the 4th metal-oxide-semiconductor (M4), the drain electrode of second metal-oxide-semiconductor (M2) is connected in the 9th node (23), the grid while of the 14 metal-oxide-semiconductor (M14) and the 6th metal-oxide-semiconductor (M6) and the grid of the 3rd metal-oxide-semiconductor (M3), the drain electrode of first metal-oxide-semiconductor (M1) is connected in protelum point (13), the source electrode of the 15 metal-oxide-semiconductor (M15) and the drain electrode of the 13 metal-oxide-semiconductor (M13) are connected in the 11 node (18), the drain electrode of the source class of the 11 metal-oxide-semiconductor (M11) and the 5th metal-oxide-semiconductor (M5) is connected in the 12 node (17), the drain electrode of the source class of the 12 metal-oxide-semiconductor (M12) and the 6th metal-oxide-semiconductor (M6) is connected in the 13 node (27), and the source electrode of the 16 metal-oxide-semiconductor (M16) and the drain electrode of the 14 metal-oxide-semiconductor (M14) are connected in the 14 node (28); In addition, the drain electrode of the 11 metal-oxide-semiconductor (M11) and the 12 metal-oxide-semiconductor (M12) links to each other with the 3rd node (21) with first node (11) respectively successively;

The current source load circuit is by 6 P type metal-oxide-semiconductors: the 7th metal-oxide-semiconductor (M7), the 8th metal-oxide-semiconductor (M8), the 9th metal-oxide-semiconductor (M9), the tenth metal-oxide-semiconductor (M10), the 17 metal-oxide-semiconductor (M17), the 18 metal-oxide-semiconductor (M18) constitute, wherein, the source electrode of the 7th metal-oxide-semiconductor (M7), the 8th metal-oxide-semiconductor (M8), the 9th metal-oxide-semiconductor (M9), the tenth metal-oxide-semiconductor (M10), the 17 metal-oxide-semiconductor (M17), each pipe of the 18 metal-oxide-semiconductor (M18) meets power supply (V _Dd), the 7th metal-oxide-semiconductor (M7), the 8th metal-oxide-semiconductor (M8), the 9th metal-oxide-semiconductor (M9), the tenth metal-oxide-semiconductor (M10), the 17 metal-oxide-semiconductor (M17), the grid of each pipe of the 18 metal-oxide-semiconductor (M18) is connected in the 15 node (14), the external biasing circuit of the 15 node (14) is to provide the static direct current electric current of current source load circuit, the drain electrode of the 7th metal-oxide-semiconductor (M7) and the tenth metal-oxide-semiconductor (M10) links to each other with the 3rd node (21) with first node (11) respectively successively, the drain electrode of the 17 metal-oxide-semiconductor (M17) and the drain electrode of the 15 metal-oxide-semiconductor (M15) are connected in the 16 node (19), constitute the second output node (i _On), the drain electrode of the 18 metal-oxide-semiconductor (M18) and the drain electrode of the 16 metal-oxide-semiconductor (M16) are connected in the 17 node (29), constitute the first output node (i _Op);

2 P type metal-oxide-semiconductors: the 19 metal-oxide-semiconductor (Mp8) and the 20 metal-oxide-semiconductor (Mp9), the source class of these 2 metal-oxide-semiconductors meets power supply (V _Dd), and grid connects the 18 node (16) after linking to each other, the 18 node (16) is the Voltage Feedback point of common mode feedback circuit, and the drain electrode of the 19 metal-oxide-semiconductor (Mp8) links to each other with the drain electrode of the 8th metal-oxide-semiconductor (M8) in the current source load circuit after protelum point (13) links to each other with the drain electrode of first metal-oxide-semiconductor (M1); The drain electrode of the 20 metal-oxide-semiconductor (Mp9) links to each other with the drain electrode of the 9th metal-oxide-semiconductor (M9) in the current source load circuit after the drain electrode of second metal-oxide-semiconductor (M2) in the 9th node (23) and the turnover voltage follower links to each other, so that will convert the common-mode point of regulating the current source load circuit behind the current signal from the voltage signal that common mode feedback circuit feeds back to.

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