Comparator circuit having clamping function

Abstract

The invention discloses a circuit, and in particular relates to a comparator circuit having a clamping function. The comparator circuit comprises a NMOS transistor, a PMOS transistor and a comparator; the source of the NMOS transistor is short-circuited with a substrate; the drain of the NMOS transistor is connected with a power supply; the source of the PMOS transistor is short-circuited with the substrate; the drain of the PMOS transistor is connected with the ground; one input end of the comparator is connected to the sources of the NMOS transistor and the PMOS transistor; the input end of the comparator is connected to input voltage through resistance; another input end of the comparator is connected to reference voltage; and the output end of the comparator is connected with an external circuit. By mans of the circuit structure disclosed by the invention, relatively high requirements on the reference voltage driving capability is avoided; furthermore, the substrate deviation effect can be effectively overcome; and the voltage application range is relatively wide.

Description

technical field [0001] The invention relates to a circuit, in particular to a comparator circuit with a clamping function. Background technique [0002] In some electronic drive systems, the control circuit needs to use external signals to make correct judgments, such as phase detection, zero-crossing detection, etc. In the zero-crossing detection circuit, a comparator is usually used as a detection technical solution. And because the detection circuit is an integrated circuit, its own withstand voltage is limited, and the fluctuation range of the external input signal may exceed the withstand voltage range of the circuit, causing damage to the circuit, so a clamping circuit is usually set at the position of the input signal for protection. [0003] There are two common clamping circuit methods, which are as follows: [0004] (1) The first is a diode clamp circuit, as attached figure 1 As shown, the circuit is composed of a diode and a comparator. The positive phase input ...

AI Technical Summary

Problems solved by technology

The disadvantage of this circuit structure is: VF1 needs to have sufficient load capacity to prevent the voltage deviation of VF1 itself due to insufficient drive capacity and lose the clamping effect

However, the disadvantage of this structure is: because of the lining bias effect caused by the difference between the substrate voltage and the source voltage of the MOS transistor, the turn-on voltage value of the MOS will vary widely, and the application voltage range is limited.

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