CN107395146B

CN107395146B - Constant transconductance amplifier circuit

Info

Publication number: CN107395146B
Application number: CN201710603007.6A
Authority: CN
Inventors: 不公告发明人
Original assignee: Shanghai Juntao Technology Co ltd
Current assignee: Shanghai Juntao Technology Co.,Ltd.
Priority date: 2017-07-22
Filing date: 2017-07-22
Publication date: 2021-04-27
Anticipated expiration: 2037-07-22
Also published as: CN107395146A

Abstract

The invention provides a constant transconductance amplifier circuit, and belongs to the technical field of semiconductor integrated circuits. The technical problem that the transconductance of the conventional transconductance amplifier changes greatly along with the application environment is solved. The circuit includes: the first PMOS transistor, the second PMOS transistor, the third PMOS transistor, the fourth PMOS transistor, the fifth PMOS transistor, the first NMOS transistor, the second NMOS transistor, the third NMOS transistor, the fourth NMOS transistor, the first resistor and the second resistor. The constant transconductance amplifier circuit of the invention introduces a first resistor and a second resistor on the basis of the traditional transconductance amplifier circuit. The transconductance of the transconductance amplifier is independent of the magnitude of the bias current, the magnitude of the input pair transistor and the working state of the transconductance amplifier. If the constant transconductance amplifier is applied to a power supply system such as DC-DC, the loop stability of the system is greatly facilitated.

Description

Constant transconductance amplifier circuit

Technical Field

The invention belongs to the technical field of semiconductor integrated circuits, and particularly relates to a constant transconductance amplifier circuit.

Background

A transconductance amplifier is an amplifier that converts an input differential voltage into an output current and is thus a voltage controlled current source. In a power supply system such as DC-DC, a transconductance amplifier is often required to amplify a voltage difference between a feedback point of an output voltage and a reference voltage, and a negative feedback loop is constructed to obtain a stable output voltage.

The conventional transconductance amplifier is shown in fig. 1, and comprises a first PMOS transistor P1, a second PMOS transistor P2, a third PMOS transistor P3, a fourth PMOS transistor P4, a fifth PMOS transistor P5, a first NMOS transistor N1, a second NMOS transistor N2, a third NMOS transistor N3, and a fourth NMOS transistor N4. The source electrode of the first PMOS transistor P1 is connected with the power supply, and the grid electrode and the drain electrode are connected with the grid electrode of the second PMOS transistor P2 and the drain electrode of the first NMOS transistor N1; the source electrode of the second PMOS transistor P2 is connected with the power supply, and the drain electrode is connected with the output end OUT of the transconductance amplifier; the source electrode of the third PMOS transistor P3 is connected with a power supply, the grid electrode is connected with a BIAS current input end BIAS, and the drain electrode is connected with the source electrodes of the fourth PMOS transistor P4 and the fifth PMOS transistor P5; the gate of the fourth PMOS transistor P4 is connected to the negative input terminal INN of the transconductance amplifier, and the drain is connected to the gate and the drain of the second NMOS transistor N2 and the gate of the first NMOS transistor N1; the gate of the fifth PMOS transistor P5 is connected to the positive input terminal INP of the transconductance amplifier, and the drain is connected to the gate and the drain of the third NMOS transistor N3 and the gate of the fourth NMOS transistor N4; the sources of the first NMOS transistor N1, the second NMOS transistor N2, the third NMOS transistor N3, and the fourth NMOS transistor N4 are all grounded, and the drain of the fourth NMOS transistor N4 is connected to the output terminal OUT of the transconductance amplifier.

The transconductance of the traditional transconductance amplifier is influenced by various factors such as the size of an input differential pair transistor, the size of input bias current, the size of input voltage, the size of source voltage and the like, and the traditional transconductance amplifier has large variation along with the application environment. In many applications such as DC-DC converters, the transconductance amplifier is an important component of the negative feedback loop, and the size of the transconductance directly determines the stability of the negative feedback loop. In this case, a transconductance amplifier with constant transconductance is required to ensure that the negative feedback loop can work normally under various conditions.

Disclosure of Invention

The invention provides a constant transconductance amplifier circuit, aiming at solving the technical problem that the transconductance of the existing transconductance amplifier changes greatly along with the application environment.

A constant transconductance amplifier circuit, comprising: a first PMOS transistor P1, a second PMOS transistor P2, a third PMOS transistor P3, a fourth PMOS transistor P4, a fifth PMOS transistor P5, a first NMOS transistor N1, a second NMOS transistor N2, a third NMOS transistor N3, a fourth NMOS transistor N4, a first resistor R1, and a second resistor R2; the source electrode of the first PMOS transistor P1 is connected with the power supply, and the grid electrode and the drain electrode are connected with the grid electrode of the second PMOS transistor P2 and the drain electrode of the first NMOS transistor N1; the source electrode of the second PMOS transistor P2 is connected with the power supply, and the drain electrode is connected with the output end OUT of the transconductance amplifier circuit; the source electrode of the third PMOS transistor P3 is connected with the power supply, the grid electrode is connected with the BIAS current input end BIAS, and the drain electrode is connected with one end of the first resistor R1 and one end of the second resistor R2; the other end of the first resistor R1 is connected with the source electrode of the fourth PMOS transistor P4; the other end of the second resistor R2 is connected with the source electrode of the fifth PMOS transistor P5; the gate of the fourth PMOS transistor P4 is connected to the negative input terminal INN of the transconductance amplifier, and the drain is connected to the gate and the drain of the second NMOS transistor N2 and the gate of the first NMOS transistor N1; the gate of the fifth PMOS transistor P5 is connected to the positive input terminal INP of the transconductance amplifier, and the drain is connected to the gate and the drain of the third NMOS transistor N3 and the gate of the fourth NMOS transistor N4; the sources of the first NMOS transistor N1, the second NMOS transistor N2, the third NMOS transistor N3, and the fourth NMOS transistor N4 are all grounded, and the drain of the fourth NMOS transistor N4 is connected to the output terminal OUT of the transconductance amplifier.

Further, the resistance values of the first resistor R1 and the second resistor R2 are equal.

The constant transconductance amplifier circuit of the invention is based on the traditional transconductance amplifier circuit, and a first resistor R1 and a second resistor R2 are introduced. The transconductance of a conventional transconductance amplifier is mainly determined by the transconductance gm of the input pair transistors. However, after RS 1R 2 is introduced, the transconductance of the transconductance amplifier is gm/(1+ gm RS), and when RS is much larger than 1/gm, the transconductance of the transconductance amplifier becomes 1/RS, which is independent of the magnitude of the bias current, the magnitude of the input pair transistors and the operating state of the transconductance amplifier. If the constant transconductance amplifier is applied to a power supply system such as DC-DC, the loop stability of the system is greatly facilitated.

Drawings

Fig. 1 is a schematic circuit diagram of a conventional transconductance amplifier;

fig. 2 is a schematic circuit diagram of the constant transconductance amplifier according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

The invention provides a constant transconductance amplifier circuit, aiming at solving the technical problem that the transconductance of the existing transconductance amplifier changes greatly along with the application environment. As shown in figure 2 of the drawings, in which,

the method comprises the following steps: a first PMOS transistor P1, a second PMOS transistor P2, a third PMOS transistor P3, a fourth PMOS transistor P4, a fifth PMOS transistor P5, a first NMOS transistor N1, a second NMOS transistor N2, a third NMOS transistor N3, a fourth NMOS transistor N4, a first resistor R1, and a second resistor R2; the source electrode of the first PMOS transistor P1 is connected with the power supply, and the grid electrode and the drain electrode are connected with the grid electrode of the second PMOS transistor P2 and the drain electrode of the first NMOS transistor N1; the source electrode of the second PMOS transistor P2 is connected with the power supply, and the drain electrode is connected with the output end OUT of the transconductance amplifier circuit; the source electrode of the third PMOS transistor P3 is connected with the power supply, the grid electrode is connected with the BIAS current input end BIAS, and the drain electrode is connected with one end of the first resistor R1 and one end of the second resistor R2; the other end of the first resistor R1 is connected with the source electrode of the fourth PMOS transistor P4; the other end of the second resistor R2 is connected with the source electrode of the fifth PMOS transistor P5; the gate of the fourth PMOS transistor P4 is connected to the negative input terminal INN of the transconductance amplifier, and the drain is connected to the gate and the drain of the second NMOS transistor N2 and the gate of the first NMOS transistor N1; the gate of the fifth PMOS transistor P5 is connected to the positive input terminal INP of the transconductance amplifier, and the drain is connected to the gate and the drain of the third NMOS transistor N3 and the gate of the fourth NMOS transistor N4; the sources of the first NMOS transistor N1, the second NMOS transistor N2, the third NMOS transistor N3, and the fourth NMOS transistor N4 are all grounded, and the drain of the fourth NMOS transistor N4 is connected to the output terminal OUT of the transconductance amplifier.

The resistance values of the first resistor R1 and the second resistor R2 are equal for the following action of the positive and negative input terminals.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims

1. A constant transconductance amplifier circuit, comprising: a first PMOS transistor P1, a second PMOS transistor P2, a third PMOS transistor P3, a fourth PMOS transistor P4, a fifth PMOS transistor P5, a first NMOS transistor N1, a second NMOS transistor N2, a third NMOS transistor N3, a fourth NMOS transistor N4, a first resistor R1, and a second resistor R2; the source electrode of the first PMOS transistor P1 is connected with the power supply, and the grid electrode and the drain electrode are connected with the grid electrode of the second PMOS transistor P2 and the drain electrode of the first NMOS transistor N1; the source electrode of the second PMOS transistor P2 is connected with the power supply, and the drain electrode is connected with the output end OUT of the transconductance amplifier circuit; the source electrode of the third PMOS transistor P3 is connected with the power supply, the grid electrode is connected with the BIAS current input end BIAS, and the drain electrode is connected with one end of the first resistor R1 and one end of the second resistor R2; the other end of the first resistor R1 is connected with the source electrode of the fourth PMOS transistor P4; the other end of the second resistor R2 is connected with the source electrode of the fifth PMOS transistor P5; the gate of the fourth PMOS transistor P4 is connected to the negative input terminal INN of the transconductance amplifier, and the drain is connected to the gate and the drain of the second NMOS transistor N2 and the gate of the first NMOS transistor N1; the gate of the fifth PMOS transistor P5 is connected to the positive input terminal INP of the transconductance amplifier, and the drain is connected to the gate and the drain of the third NMOS transistor N3 and the gate of the fourth NMOS transistor N4; the sources of the first NMOS transistor N1, the second NMOS transistor N2, the third NMOS transistor N3 and the fourth NMOS transistor N4 are all grounded, and the drain of the fourth NMOS transistor N4 is connected with the output end OUT of the transconductance amplifier;

the resistance values of the first resistor R1 and the second resistor R2 are equal.