CN113179097A

CN113179097A - Circuit for converting positive voltage level to negative voltage level

Info

Publication number: CN113179097A
Application number: CN202110613334.6A
Authority: CN
Inventors: 王洋
Original assignee: Nanjing Vocational University of Industry Technology NUIT
Current assignee: Nanjing Vocational University of Industry Technology NUIT
Priority date: 2021-06-02
Filing date: 2021-06-02
Publication date: 2021-07-27

Abstract

The invention discloses a circuit for converting a positive voltage level into a negative voltage level, which comprises a bias circuit and a level conversion core circuit which are sequentially connected, wherein the bias circuit generates a bias signal to provide a direct current working point for the level conversion core circuit, and the level conversion core circuit converts an input positive voltage level signal into a negative voltage level signal in the circuit. The input positive voltage level signal can be converted into a required negative voltage level signal through the bias circuit and the level conversion core circuit, single-channel conversion is achieved, and the conversion structure is simple. In addition, all devices in the circuit can be realized based on conventional low-voltage CMOS devices, special high-voltage CMOS devices are not needed, the working speed is high, the process is easy to integrate, the occupied chip area is small, and the multichannel application is easy to expand.

Description

Circuit for converting positive voltage level to negative voltage level

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a circuit for converting a positive voltage level into a negative voltage level.

Background

In industrial control and communication systems, a standard TTL/CMOS positive voltage level signal from the outside is often required to be converted into a negative level signal required inside a circuit, for example, a 0/+5v voltage signal is converted into a-5/0 v voltage signal. The conventional level conversion circuit is usually realized based on a high-voltage-resistant device, and has high requirements on the characteristics of discrete devices during circuit board level realization, so that the economy and convenience are not facilitated, and the selection range of the devices is limited. When the integrated circuit chip level is realized, the special requirement that a high voltage resistant device is required is provided for the device process, the conventional process integration is not facilitated, the actual chip area occupied by the high voltage resistant device is larger, and the application range and the flexibility of the high voltage resistant device are limited.

Disclosure of Invention

In order to solve the above problems in the prior art, an object of the present invention is to provide a circuit for converting a positive voltage level to a negative voltage level, which can reliably complete the conversion from a positive voltage level signal to a negative voltage level signal, avoid using a high voltage special device, and can be directly integrated and applied in a conventional low voltage CMOS process.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a circuit for converting a positive voltage level into a negative voltage level comprises a bias circuit and a level conversion core circuit which are sequentially connected, wherein the bias circuit generates a bias signal to provide a direct current working point for the level conversion core circuit, and the level conversion core circuit converts an input positive voltage level signal into a negative voltage level signal in the circuit;

the bias circuit comprises a first PMOS tube, a first NMOS tube and a second NMOS tube, wherein a drain electrode of the first PMOS tube is connected with a drain electrode of the first NMOS tube and then outputs a first level signal, a source electrode of the first PMOS tube is grounded, a grid electrode of the first PMOS tube is connected with a drain electrode of the first PMOS tube, a source electrode of the first NMOS tube is connected with a drain electrode of the second NMOS tube and then outputs a second level signal, a grid electrode of the first NMOS tube is connected with a drain electrode of the first NMOS tube, a source electrode of the second NMOS tube is connected to a negative voltage power supply, and a grid electrode of the second NMOS tube is connected with a drain electrode of the second NMOS tube;

the level conversion core circuit comprises a second PMOS tube, a third NMOS tube, a fourth NMOS tube and a fifth NMOS tube, wherein a grid electrode of the second PMOS tube is connected with a grid electrode of the fourth NMOS tube and then grounded, a source electrode of the second PMOS tube is used for inputting a positive voltage level signal, a drain electrode of the second PMOS tube is connected with a drain electrode of the third NMOS tube, a source electrode of the third NMOS tube is connected with a drain electrode of the fourth NMOS tube, a grid electrode of the third NMOS tube is connected with a drain electrode of the third NMOS tube, a grid electrode of the fifth NMOS tube is connected with a first level signal, a source electrode of the fifth NMOS tube is connected with a second level signal, and a source electrode of the fourth NMOS tube is connected with a drain electrode of the fifth NMOS tube and then outputs a converted negative level signal.

As a further improvement of the present invention, the level conversion core circuit is provided in plurality according to the number of input level signals, and each level conversion core circuit is connected to the bias circuit.

As a further improvement of the present invention, the positive voltage level signal is a positive voltage level pulse signal including a +5/0V pulse signal or a +3.3/0V pulse signal.

As a further improvement of the invention, the positive voltage level pulse signal is a TTL or CMOS signal.

Compared with the prior art, the invention has the following beneficial effects:

1) according to the circuit for converting the positive voltage level into the negative voltage level, disclosed by the invention, an input positive voltage level signal can be converted into a required negative voltage level signal through the bias circuit and the level conversion core circuit, the single-channel conversion is realized, and the conversion structure is simple.

2) According to the circuit for converting the positive voltage level to the negative voltage level, all devices in the circuit can be realized based on conventional low-voltage CMOS devices, special high-voltage CMOS devices are not needed, the working speed is high, the process is easy to integrate, the occupied chip area is small, and the multichannel application is easy to expand.

Drawings

FIG. 1 is a classic positive-negative level shift circuit;

FIG. 2 is a schematic block diagram of a level shift core circuit in the present invention;

FIG. 3 is a transistor level schematic of a level shift core circuit of the present invention;

fig. 4 is a test plot of output voltage versus input voltage in accordance with the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention relates to a circuit for converting a positive voltage level into a negative voltage level, which comprises a bias circuit 1 and a level conversion core circuit 2 which are sequentially connected, wherein the bias circuit 1 generates a bias signal to provide a direct current working point for the level conversion core circuit 2, and the level conversion core circuit 2 converts an input positive voltage level signal in into a negative voltage level signal out in the circuit;

the bias circuit 1 comprises a first PMOS tube MP1, a first NMOS tube MN1 and a second NMOS tube MN2, wherein a drain electrode of the first PMOS tube MP1 is connected with a drain electrode of the first NMOS tube MN1 and then outputs a first level signal ng, a source electrode of the first PMOS tube MP1 is grounded, a grid electrode of the first PMOS tube MP1 is connected with a drain electrode of the first PMOS tube MP1, a source electrode of the first NMOS tube MN1 is connected with a drain electrode of the second NMOS tube MN2 and then outputs a second level signal ns, a grid electrode of the first NMOS tube MN1 is connected with a drain electrode of the first NMOS tube MN1, a source electrode of the second NMOS tube MN2 is connected to a negative voltage supply Vee, and a grid electrode of the second NMOS tube MN2 is connected with a drain electrode of the second NMOS tube MN 2; the bias circuit 1 generates a first level signal ng and a second level signal ns, so as to ensure the normal operation of the level conversion core circuit 2 and enable each device to operate in a safe voltage area.

The level conversion core circuit 2 includes a second PMOS transistor MP2, a third NMOS transistor MN3, a fourth NMOS transistor MN4, and a fifth NMOS transistor MN5, a gate of the second PMOS transistor MP2 is connected to a gate of the fourth NMOS transistor MN4 and then grounded, a source of the second PMOS transistor MP2 is used to input a positive voltage level signal in, a drain of the second PMOS transistor MP2 is connected to a drain of the third NMOS transistor MN3, a source of the third NMOS transistor MN3 is connected to a drain of the fourth NMOS transistor MN4, a gate of the third NMOS transistor MN4 is connected to a drain of the third NMOS transistor MN3, a gate of the fifth NMOS transistor MN5 is connected to a first level signal ng, a source of the fifth NMOS transistor MN5 is connected to a second level signal ns, and a source of the fourth NMOS transistor MN4 is connected to a drain of the fifth NMOS transistor MN5 and then outputs a converted negative level signal out. The level conversion core circuit 2 converts an input positive voltage level signal in into a negative voltage level signal out, and the bias circuit 1 and the level conversion core circuit 2 jointly form a complete positive and negative level conversion circuit.

Specifically, the number of the level conversion core circuits 2 is set to be plural according to the number of the input level signals, and each level conversion core circuit 2 is connected to the bias circuit 1. When multi-channel input level conversion is needed at the same time, only one bias circuit 1 is needed, the level conversion core circuit 2 simply copies and repeats according to the number of input signals, the grid electrode of the fifth NMOS tube MN5 in each level conversion core circuit 2 is respectively connected to the first level signal ng, and the source electrode of each fifth NMOS tube MN5 is respectively connected to the second level signal ns.

Specifically, the positive voltage level signal in is a positive voltage level pulse signal including a +5/0V pulse signal and a +3.3/0V pulse signal.

Specifically, the positive voltage level pulse signal is a TTL or CMOS signal.

The working principle of the positive and negative level conversion circuit is as follows:

(1) the first level signal ng and the second level signal ns generated by the bias circuit 1 can enable the gate-source voltage of the fifth NMOS transistor MN5 in the level shift core circuit 2 to be greater than the turn-on voltage, and whether the fifth NMOS transistor MN5 is turned on depends on the drain of the fifth NMOS transistor MN5, i.e., the out potential;

(2) when the external input positive voltage level signal in is at a high level of 5V/3.3V, the second PMOS transistor MP2 in the level conversion core circuit 2 is turned on to force the fourth NMOS transistor MN4 to be turned on, the drain potential, i.e., out, of the fifth NMOS transistor MN5 is converted to a level lower than GND by a turn-on voltage Vtho (fourth NMOS transistor MN 4), and at this time, the second PMOS transistor MP2, the third NMOS transistor MN3, the fourth NMOS transistor MN4, and the fifth NMOS transistor MN5 in the level conversion core circuit 2 are all in a conducting state, and the current thereof is controlled by the bias circuit 1;

(3) when the voltage of the externally input positive voltage level signal in is low level 0V, the second PMOS transistor MP2 in the level conversion core circuit 2 is turned off, forcing the fourth NMOS transistor MN4 to be turned off, the drain potential of the fifth NMOS transistor MN5, i.e., out, to be converted to be equal to ns, i.e., higher than the negative voltage power supply vee by the level of the turn-on voltage Vtho (second NMOS transistor MN 2), and at this time, the second PMOS transistor MP2, the third NMOS transistor MN3, the fourth NMOS transistor MN4, and the fifth NMOS transistor MN5 in the level conversion core circuit 2 are all in the off state;

(4) as can be seen from the above-described process, the bias circuit 1 and the level conversion core circuit 2 can convert the positive voltage pulses 5V/3.3V, 0V of the external input in terminal to-Vtho, Vee + Vtho levels of the output out terminal as shown in fig. 4. Because the starting voltage Vtho of the low-voltage device is about 0.7V, when the negative voltage power supply Vee is-5V, the output out end is-0.7V-4.3V, and when the negative voltage power supply Vee is-3V, the output out end is-0.7V-2.3V, the conversion from the positive voltage level to the negative voltage level is completed, and the later stage can be reliably processed only by a simple CMOS circuit;

(5) under two input conditions of the input end in, all transistors of the bias circuit 1 and the level conversion core circuit 2 can constantly keep the voltage difference of drain-source, gate-source and gate-drain of all devices to be less than 5V, so that the level conversion circuit can be completely realized based on the conventional low-voltage CMOS process without special high-voltage CMOS devices.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A circuit for converting a positive voltage level to a negative voltage level, comprising: the circuit comprises a bias circuit and a level conversion core circuit which are connected in sequence, wherein the bias circuit generates a bias signal to provide a direct current working point for the level conversion core circuit, and the level conversion core circuit converts an input positive voltage level signal into a negative voltage level signal in the circuit;

2. The circuit of claim 1, wherein the positive voltage level to the negative voltage level is selected from the group consisting of: the level conversion core circuits are arranged in a plurality according to the number of input level signals, and each level conversion core circuit is connected with a bias circuit.

3. The circuit of claim 1, wherein the positive voltage level to the negative voltage level is selected from the group consisting of: the positive voltage level signal is a positive voltage level pulse signal, and the positive voltage level pulse signal comprises a +5/0V pulse signal or a +3.3/0V pulse signal.

4. A circuit for positive voltage level to negative voltage level conversion according to claim 3, wherein: the positive voltage level pulse signal is a TTL or CMOS signal.