High-precision ADC input signal control circuit

Abstract

The invention discloses a high-precision ADC input signal control circuit in the technical field of control circuits. The circuit comprises a clock control switch and a forward and reverse bias diode.A charging and discharging circuit formed by the clock control switch and the forward and reverse bias diode controls the voltage level of a clock so that a switch control signal is synchronously converted along with the voltage level of the input signal, and the distortion of the circuit is reduced; and the node voltage is Vcc-Vthp+Vin when the clock is at a high level, and the gate voltage of the sampling NMOS is always higher than the input signal by Vcc-Vthp to obtain the function of the low-distortion sampling circuit. According to the invention, the charging and discharging circuit formed by the clock control switch and the forward and reverse bias diode is used for adjusting the clock voltage level, the performance is stable, the waveform distortion degree is low, the circuit can be stabilized in a short time, the occupied chip area is smaller, and the performance of the sampling boost driving sampling circuit is greatly improved.

Description

technical field [0001] The invention relates to the technical field of control circuits, in particular to a high-precision ADC input signal control circuit. Background technique [0002] The sampling boost sampling circuit is widely used in various analog-to-digital converters such as Pipeline AD, Delta-SigmaADC and other mixed-signal circuit systems such as filters and digital-to-analog converters, which are used to sample the input signal voltage at discrete time points, Discrete signal processing is then performed; [0003] Such as figure 1 is a characteristic of the NMOS and PMOS channel resistance. When the gate voltage of the transistor is fixed, the channel resistance changes with the input signal voltage, so if it is used directly in the sampling circuit, it will cause great circuit distortion. [0004] In order to overcome the variation of the channel resistance with the input voltage, the parallel connection of PMOS and NMOS (transmission gate) is usually used. ...

AI Technical Summary

Problems solved by technology

However, due to the use of coupling capacitors and charge pumps in the traditional sampling boost circuit, the control voltage will attenuate, the circuit is difficult to stabilize, and it occupies a large chip area.

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