Digital-output two-stage double-precision biomedical capacitance sensor interface circuit

Abstract

The invention discloses a digital-output two-stage double-precision biomedical capacitance sensor interface circuit. The circuit is formed by a capacitance time conversion circuit and a time-to-digital conversion circuit. Two-stage double-precision oscillators are used to generate two reference signals of low precision and high precision, double-precision measurement is carried out on measured capacitance, and measurement time is reduced while capacitance measurement precision is improved; at the same time, capacitance values of externally connected reference capacitors and frequency divisionmultiple of an externally controlled programmable frequency divider can be adjusted according to the size of the measured capacitance, and non-fixed capacitance detection of a wide range and the highprecision is realized; a logic control unit structure enables measurement to be completed by the double-precision reference signals in one cycle of a measured signal after frequency dividing, and themeasurement time is reduced; and changes of the capacitance are directly converted into digitally encoded output, analog-to-digital conversion units can be decreased, cascading with a subsequent chipis facilitated, and capacitance measurement errors are reduced.

Description

technical field [0001] The invention relates to the technical field of integrated circuit design, in particular to a digital output two-stage double-precision biomedical capacitive sensor interface circuit. Background technique [0002] With the development of wearable smart medical devices and the rise of Internet of Things technology, biomedical capacitive sensors are widely used in various wearable smart medical devices. As a bridge connecting sensors and processing chips, sensor interface circuits are also constantly developing. , Innovation. The continuous improvement of people's demand for wearable multi-physiological signal monitoring systems requires the detection accuracy of biomedical capacitive sensors to continue to increase, the detection range to continue to expand, and the requirements for sensor interface circuits to continue to increase, low error, high precision, and low power consumption become a major challenge for biomedical sensor interface circuits. ...

AI Technical Summary

Problems solved by technology

[0003] The output of traditional biomedical capacitive sensor interface circuits is mostly continuous analog voltage signals, which cannot be directly cascaded with signal processing chips, and need to be converted again by analog-to-digital converters

The traditional digital output capacitive sensor interface circuit is a single-precision detection method with a fixed measurement range and limited measurement accuracy and flexibility.

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