Log-domain differential low-pass filter

Abstract

The invention relates to the technical field of electronic circuits, and specifically relates to a log-domain differential low-pass filter. The log-domain differential low-pass filter comprises two identically structured logarithmic compression units, a low-pass filtering unit, and an exponential expansion unit, wherein an input end of each logarithmic compression unit is connected with one path of differential input current, and the logarithmic compression units execute logarithmic compression and conversion for the input current and obtain compressed voltage signals, and further input the compressed voltage signals to the low-pass filtering unit; the input end of the low-pass filtering unit is respectively connected with output ends of the two logarithmic compression units, the low-pass filtering unit filters and processes the two paths of compressed voltage signals and obtains output voltage signals, and outputs the output voltage signals to the exponential expansion unit; and the structure of the exponential expansion unit is in mirror symmetry with the structure of the logarithmic compression units, and the exponential expansion unit expands and converts the output voltage signals, then obtains output current information, and outputs the current information. The log-domain differential low-pass filter suppresses common-mode noise well, is small in size and can be integrated more easily.

Description

technical field [0001] The invention relates to the technical field of electronic circuits, in particular to a logarithmic domain differential low-pass filter. Background technique [0002] With the advancement of science and technology, electronic medical instruments are being widely used, and electronic medical instruments need to obtain bioelectrical signals, and because the frequency of bioelectrical signals is very low, generally lower than 1 kHz. Therefore, the filtering processing of the bioelectrical signal often requires a large capacitance and resistance to obtain a large charging and discharging time constant, thereby obtaining a very low cut-off frequency. However, the portable signal acquisition system requires a small chip area, which is a severe test for the integration of large capacitors. At the same time, the portable signal acquisition system has very high requirements for power supply voltage and power consumption. In order to meet the requirements of sig...

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Problems solved by technology

In addition, the suppression of common mode noise is not ideal when using single-ended input; while two capacitors are used for double-ended input, which increases the difficulty of integration

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