Switched capacitor integrator offset voltage elimination circuit and elimination method thereof

Abstract

The invention discloses a switched capacitor integrator offset voltage elimination circuit and an elimination method thereof. The circuit comprises a first capacitor C1, a second capacitor C2, a thirdcapacitor Cload, a fourth capacitor Cf, a first switch S1, a second switch S2, a third switch RST _ PGA, a fourth switch S1d, a reference voltage Vref _ PGA, a VOS offset voltage source and an integrator. The first end of the first capacitor C1 is connected with an input signal, and the second end of the first capacitor C1 is connected with the second end of the second capacitor C2, the first endof the third capacitor Cload, the first end of the fourth capacitor Cf, the first end of the second switch S2, the first end of the third switch RST _ PGA and the first end of the VOS offset voltagesource. According to the technical scheme, the influence of a mismatched switched capacitor integrator is eliminated by optimizing a switch structure and a related double-sampling technology. The circuit is easy to implement, low in power consumption, capable of being used in a single-ended circuit and a differential circuit and wide in application range.

Description

technical field [0001] The invention relates to the technical field of fingerprint identification, in particular to a switched capacitor integrator offset voltage elimination circuit and an elimination method thereof. Background technique [0002] In consumer electronic products such as mobile phones and computers, in its key components, fingerprint recognition systems, capacitive fingerprint sensors with high integration are commonly used to realize fingerprint recognition. Due to the existence of valleys and ridges in the fingerprint texture, when the finger presses the mutual capacitance sensor array, when the electric field lines pass through the valleys and ridges, the magnitude of the mutual capacitance is also different because of the different media. Mutual-capacitance fingerprint sensors perform fingerprint recognition based on the difference in mutual capacitance between valleys and ridges. When a single transmit signal passes through the valley-ridge capacitance,...

AI Technical Summary

Problems solved by technology

[0004] The invention provides a switched capacitor integrator offset voltage elimination circuit and its elimination method, for the first switch, the second switch, the third switch, the fourth switch, the first capacitor, the second capacitor, the third capacitor, the The four capacitors are reasonably set to keep the potential of point A unchanged during the integration and reset process, thereby eliminating the influence of the offset voltage on the integration, and solving the influence of the amplifier mismatch on the integrator in the switched capacitor integrator in the prior art, and the accuracy of the integrator low technical issues

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