Circuit capable of eliminating NMOS single tube transmission to form static short circuit current

Abstract

A circuit used for eliminating static shortcircuit current formed by transmission of NMOS single tube consists of NMOS transmission tube and CMOS buffer circuit with two CMOS reverse controller circuits. It is featured as coupling one voltage clamp circuit between power supply end and master current path of the first CMOS reverse controller and bridge-jointing a feedback loop with input end and output end of the second CMOS reverse controller.

Description

technical field [0001] The invention relates to a circuit structure. Background technique [0002] The NMOS transmission tube has good characteristics of low-level transmission, but poor performance of high-level transmission. When the NMOS tube transmits a high level, it cannot pull up the voltage of the source to exceed VDD-V th , this voltage loss is called threshold drop. And, when the source voltage of the NMOS transistor rises, the voltage difference V between the source and the substrate sb It will cause the body effect and increase the threshold voltage, which will further weaken the strength of the signal when the high level is transmitted, and may exceed the noise tolerance of the next stage. For the next-level CMOS circuit, when the high level is transmitted, the weakened input signal causes the PMOS tube to be unable to be effectively cut off, and the PMOS tube and the NMOS tube are in the simultaneous conduction state, which will generate a static short-circu...

AI Technical Summary

Problems solved by technology

And, when the source voltage of the NMOS transistor rises, the voltage difference V between the source and the substrate sb It will cause the body effect and increase the threshold voltage, which will further weaken the strength of the signal when the high level is transmitted, and may exceed the noise tolerance of the next level

For the next-level CMOS circuit, when the high level is transmitted, the weakened input signal causes the PMOS tube to be unable to be effectively cut off, and the PMOS tube and the NMOS tube are in the simultaneous conduction state, which will generate a static short-circuit current. This current increases power consumption of the circuit

[0003] The existing common solution is to connect NMOS transistors and PMOS transistors in parallel to form dual-transistor transmission gates to eliminate the problem of threshold drop, but in some applications such as large-scale programmable logic devices, there are a large number of transmission gate circuits, such as multiple Selector switch, switch matrix, etc., if the dual-transistor transmission structure is used, the circuit area consumption will be too large

Another solution is to add a pressurized structure to compensate for the threshold drop by increasing the gate voltage of the NMOS transmission tube, but the disadvantage of this structure is that the circuit is too complicated and difficult to design

Another design is to add a feedback loop to the CMOS circuit, but due to the bidirectional conduction characteristics of the NMOS transmission tube, the function of the feedback loop can affect the input drive through the transmission tube, which may lead to circuit performance degradation or even functional failure.

Therefore, the existing design has the disadvantages of large circuit area consumption, complex structure, and great influence on the performance and function of the original circuit.

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