Grid voltage bootstrapped switch with low on-resistance and substrate bias effect elimination method thereof

Abstract

The invention relates to the field of integrated circuits and discloses a grid voltage bootstrapped switch with low on-resistance and a substrate bias effect elimination method thereof. According to the invention, a substrate of M1 which plays a switch role is not in direct short-circuiting with a source end of the M1 and is connected with the source end of the M1 through a control switch; when a grid voltage bootstrapped circuit is in a precharging mode, the control switch is at an turn-off state; and when the grid voltage bootstrapped circuit is in a bootstrapped mode, the control switch is at a turn-on state. Therefore, when the grid voltage bootstrapped circuit is in the precharging mode, the substrate of the M1 is grounded equivalently to ensure the thorough turn-off of the M1; and when the grid voltage bootstrapped switch is in the bootstrapped mode, the substrate of the M1 is communicated with a drain end of the M1 through the control switch, so that the substrate bias effect is eliminated, and the on-resistance of the switch M1 is kept unchanged no matter how many input signals are.

Description

Technical field [0001] The invention relates to the field of integrated circuits, and in particular to a technology for eliminating the offset effect of a gate voltage bootstrap switch. Background technique [0002] In analog circuits, MOS (metal oxide semiconductor) transistors are usually used to realize the switch function. Take the N-type MOS switch as an example. The on-resistance of the MOS tube is related to the voltage from the gate to the source. The smaller the voltage, the larger the on-resistance. Generally, when the switch is turned on, the gate voltage is fixed at a high level, and the source is connected to the input signal. Therefore, the on-resistance will change with the change of the input signal, especially when the signal voltage is close to the gate voltage, the N-type MOS transistor is approximately turned off. In order to process higher voltage signals, the gate is usually connected to the highest level, that is, the power supply voltage, provided that t...

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Problems solved by technology

[0004] However, the turn-on voltage of the NMOS transistor is not only related to the voltage from the gate to the source, but also related to the voltage from the source to the substrate. The more the source is higher than the substrate voltage, the more obvious the lining bias effect is, and the threshold voltage is lower. The higher the value, the greater the on-resistance

In order to eliminate the background offset effect, the substrate and source terminals of M1 are usually shorted, but in figure 1 In the circuit, this will cause M1 to be unable to turn off effectively, because when the input signal is high, the input signal will conduct through the PN junction of the substrate and drain and the other end of the switch

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