A CMOS voltage comparator

Abstract

The invention is a CMOS voltage comparer, a multistage amplifier, where, for each one, the first output end is connected with the first input end by a switch and the second output end connected with the second input end by a switch, the two switches are opened or closed at the same time; the input end of each amplifier is connected with the output end of the previous amplifier and the switches of all the amplifiers are opened or closed at the same time; a double-arrival single-converting circuit with two input ends connected with two output ends of the last amplifier; a multistage output reshaping circuit, where one input end is connected with one output end of the double-arrival single-converting circuit; DC isolating capacitors, situated in front of the input ends of all the amplifiers and the double-arrival single-converting circuit; a first switch, where an input signal is connected to the primary amplifier through the first switch and then an DC isolating capacitor; a second switch, where the other input signal is grounded through the second switch and the second switch and all the switches of the multistage amplifier are opened or closed at the same time.

Description

technical field [0001] The invention relates to a voltage comparator, in particular to a CMOS voltage comparator composed of multi-level circuits. Background technique [0002] In the traditional comparator in the integrated circuit, the operational amplifier is usually used as the comparator, and the comparison function is realized by utilizing the characteristic of the large open-loop gain of the operational amplifier. If the input voltage of the positive terminal is higher than that of the negative terminal, the output will be a high level; if the input voltage of the positive terminal is lower than that of the negative terminal, a low level will be output. In this way, the comparison of the input voltage of the positive and negative input terminals is realized. The functional block diagram and working principle diagram of the circuit are shown in figure 1 as shown, figure 1 (a) is a functional block diagram, figure 1 (b) is the working principle diagram, in which the...

AI Technical Summary

Problems solved by technology

[0003] Due to the existence of the offset voltage of the op amp, it will affect the accuracy of the comparator

And because the open-loop gain of the op amp is very large, a small offset voltage may cause the circuit to saturate

thus not working properly

[0004] Due to the lack of positive feedback, the speed of the comparator is limited by the slew rate (SLEW RATE) of the op amp. Due to the use of a single-stage op amp, the switching speed is very slow, resulting in a very slow slew rate.

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