CN106301348B

CN106301348B - Quasi push-pull source follower

Info

Publication number: CN106301348B
Application number: CN201610966353.6A
Authority: CN
Inventors: 张南阳; 张仁富; 李文亮
Original assignee: Hangzhou Sitai Microelectronics Co ltd
Current assignee: Hangzhou Sitai Microelectronics Co ltd
Priority date: 2016-10-28
Filing date: 2016-10-28
Publication date: 2023-10-13
Anticipated expiration: 2036-10-28
Also published as: CN106301348A

Abstract

The invention relates to the technical field of analog integrated circuits, in particular to a quasi push-pull source follower, which has a simple circuit structure and can realize the stability of circuit bandwidth under different power supply voltages, and comprises a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5 and a transistor M6, and is characterized in that the drain electrode of the transistor M5 is connected with the drain electrode of the transistor M6 and then is connected with the source electrode of a current tube M7, and the grid electrode of the current tube M7 is connected with a reference voltage Vref2 and the drain electrode is grounded.

Description

Quasi push-pull source follower

Technical Field

The invention relates to the technical field of analog integrated circuits, in particular to a quasi push-pull source-stage follower.

Background

With the development of optical fiber communication, the speed of optical fiber transmission is faster and faster, and the speed requirement for LDD (laser driver) is also faster and faster. Source followers are an important component of LDDs, mainly to provide high bandwidth speed for the driver.

Depending on the application conditions, the LDD needs to operate at different supply voltages. While the bandwidth speed of the conventional circuit is variable under different power supply voltages, the bandwidth is high under high voltage, and the bandwidth is reduced under low voltage, so that the operation speed of the LDD is unstable.

As shown in fig. 1, the bandwidth of the conventional quasi-push-pull source follower circuit is:

the gate voltages of transistor M5 and transistor M6 in the circuit are voltage dependent. As the voltage increases, the current through transistor M5 and transistor M6 also increases, resulting in an increase in the transconductance gm5 of transistor M5 and transistor M6. At the same time, the current through transistor M1 and transistor M2 increases, so does the transconductance gm1, and gm1-gm5, and the bandwidth of the circuit, as shown in FIG. 3.

Disclosure of Invention

In order to solve the above problems, the present invention provides a quasi-push-pull source follower, which has a simple circuit structure and can realize the stability of circuit bandwidths under different power supply voltages.

The technical scheme is as follows: the utility model provides a quasi push-pull source follower, its includes transistor M1, transistor M2, transistor M3, transistor M4, transistor M5 and transistor M6, the source of transistor M1 with connect back ground behind the source of transistor M2, the grid of transistor M1 with the grid of transistor M2 all connects input voltage Vin, the drain electrode of transistor M1 connects the source of transistor M3, the source of transistor M5, the drain electrode of transistor M2 connects the source of transistor M4, the source of transistor M6, the grid of transistor M3 with the grid of transistor M4 connects back ground behind reference voltage Vref1, the drain electrode of transistor M3 with the drain electrode of transistor M4 connects back ground, the source of transistor M5 with the grid of transistor M6 links, the grid of transistor M5 with the source of transistor M6 links, the drain electrode of transistor M5 is connected with the drain electrode of transistor M6, the drain electrode of transistor M7 is characterized in that the drain electrode of transistor M7 is connected with the drain electrode of transistor M6.

After the circuit structure of the invention is adopted, the current tube M7 is added under the transistor M5 and the transistor M6 with the grid electrode and the drain electrode mutually intersected, the grid electrode of the current tube M7 is additionally connected with the reference voltage Vref2, the current passing through the current tube M7 is the same under different power supply voltages, the current passing through the transistor M5 and the transistor M6 is the same, therefore, the transconductance gm5 of the transistor M5 and the transistor M6 is unchanged, the current passing through the transistor M1 and the transistor M2 is also unchanged, the transconductance gm1 of the transistor M1 and the transistor M2 is also constant, therefore, gm1-gm5 is also unchanged, the bandwidth of the circuit is stable, the stability of the circuit bandwidth under different power supply voltages is realized, and the circuit structure is simple.

Drawings

FIG. 1 is a diagram of a conventional quasi-push-pull source follower;

FIG. 2 is a schematic diagram of a circuit structure of the present invention;

FIG. 3 is a schematic diagram of the circuit bandwidth of a conventional quasi-push-pull source follower;

fig. 4 is a schematic diagram of the circuit bandwidth of the present invention.

Detailed Description

Referring to fig. 2 and fig. 4, a quasi push-pull source follower includes a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5 and a transistor M6, wherein a source of the transistor M1 is connected to a source of the transistor M2 and then to a power supply VDD, a gate of the transistor M1 and a gate of the transistor M2 are both connected to an input voltage Vin, a drain of the transistor M1 is connected to a source of the transistor M3 and a source of the transistor M5, a drain of the transistor M2 is connected to a source of the transistor M4 and a source of the transistor M6, a gate of the transistor M3 is connected to a gate of the transistor M4 and then to a reference voltage Vref1, a drain of the transistor M3 is connected to a drain of the transistor M4 and then to a ground, a source of the transistor M5 is connected to a gate of the transistor M6, a source of the transistor M5 is connected to a source of the transistor M6 and a source of the transistor Vout is an output terminal.

Claims

1. The utility model provides a quasi push-pull source follower, its includes transistor M1, transistor M2, transistor M3, transistor M4, transistor M5 and transistor M6, the source of transistor M1 with connect back ground behind the source of transistor M2, the grid of transistor M1 with the grid of transistor M2 all connects input voltage Vin, the drain electrode of transistor M1 connects the source of transistor M3, the source of transistor M5, the drain electrode of transistor M2 connects the source of transistor M4, the source of transistor M6, the grid of transistor M3 with the grid of transistor M4 connects back ground behind reference voltage Vref1, the drain electrode of transistor M3 with the drain electrode of transistor M4 connects back ground, the source of transistor M5 with the grid of transistor M6 links, the grid of transistor M5 with the source of transistor M6 links, the drain electrode of transistor M5 is connected with the drain electrode of transistor M6, the drain electrode of transistor M7 is characterized in that the drain electrode of transistor M7 is connected with the drain electrode of transistor M6.