Complementary metal oxide semiconductor switch

Abstract

The invention relates to the technical field of integrated circuits, in particular to a complementary metal oxide semiconductor (CMOS) switch which comprises a first thermal trap P-shaped pipe, a second thermal trap P-shaped pipe and an N-shaped pipe, wherein an N trap of the first thermal trap P-shaped pipe is connected with a source electrode; an N trap of the second thermal trap P-shaped pipe is connected with the source electrode, and the drain electrode of the second thermal trap P-shaped pipe is connected with the drain electrode of the first thermal trap P-shaped pipe; and the source electrode of the N-shaped pipe is connected with the source electrode of the first thermal trap P-shaped pipe, and the drain electrode of the N-shaped pipe is connected with the source electrode of the second thermal trap P-shaped pipe. When the CMOS switch is disconnected, because a PN junction diode with the direction opposite to the voltage drop direction is introduced, when the N electrode of the PN junction diode is connected with a high level, the PN junction diode is in a reverse cut-off state, and thus, the isolation performance of the switch during disconnection is improved. Therefore, in a circuit structure provided with a cascade feedback system, when the switch is disconnected, the level of a feedback signal point can be well maintained, and signal distortion is reduced.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a complementary metal oxide semiconductor (CMOS) switch. Background technique [0002] In an integrated circuit, the transmission of control signals through the on and off of switches is one of the main modes of operation of Complementary Metal Oxide Semiconductor (CMOS, Complementary Metal Oxide Semiconductor) devices. At present, switched capacitor (SC, Switched-Capacitor) circuits based on CMOS switches are widely used in signal filtering, analog signal processing, and high-frequency signal processing in data acquisition systems, such as amplifiers, oscillators, and balanced modulators. , analog multipliers, peak detectors, rectifiers, digital-to-analog (D / A) and analog-to-digital (A / D) converters, analog delays for video signals, and amplitude modulation (AM) / frequency modulation (FM) communication systems part of the circuit. It can be seen that the CMOS switch...

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Problems solved by technology

But in a circuit structure with a cascaded feedback system, such as Figure 6B As shown, the feedback part is connected to the circuit by point XP through the control of switch p2 to form a feedback loop. When switches p1 and p2 are single heat sink switches, when p1 is open and p2 is closed, due to Figure 5B If the P pole of the PN junction diode shown in is connected to the high-level feedback (VREFP), the PN junction diode is forward-conducting, which seriously affects the isolation when the switch is turned off, so that the feedback signal point cannot be well maintained. level, resulting in an offset effect, resulting in severe signal distortion, and its output waveform is shown in Figure 7A shown

Depend on Figure 7A It can be seen that when the single heat sink switch p1 is closed and p2 is open, the output signal can completely follow the change of the input signal, but when the single heat sink switch p1 is open and p2 is closed, it is seriously affected by the cascade feedback system Deviates from high level feedback (VREFP), causing severe distortion of the signal

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