A second-order low-pass filter circuit based on current steering technology

Abstract

A second-order low-pass filter circuit based on current steering technology, the input end of the first resistor is used as the input end of the second-order low-pass filter circuit, and the output end is connected to the input end of the third resistor; the lower plate of the second capacitor Connect the output terminal of the third resistor and the output terminal of the operational amplifier and serve as the output terminal of the second-order low-pass filter circuit, the upper plate is connected with the negative input terminal of the operational amplifier; the upper plate of the first capacitor is connected with the second resistor The input terminal, the lower plate is connected to the positive input terminal of the operational amplifier and connected to the common mode level; the first current steering module is used to shunt the output current of the first resistor to flow into the input terminal of the second resistor and flow out of the second-order low The signal path of the pass filter circuit; the second current steering module is used to divide the output current of the second resistor into two parts of current, and then flow into the second capacitor and flow out of the signal path of the second-order low-pass filter circuit. The invention reduces the requirement of the low-pass filter for large passive components and facilitates on-chip integration.

Description

technical field [0001] The invention belongs to the technical field of analog integrated circuits, and in particular relates to a circuit structure for realizing high-order low-pass filtering in an analog manner based on current steering technology. Background technique [0002] With the rapid development of biomedical and bioelectronic industries, the demand for consumer medical electronic products is increasing day by day. Various sensor acquisition and readout circuits are used to detect and process different bioelectrical signals. On the other hand, the design and manufacture of CMOS integrated circuits tend to be high-density, high-speed and high-precision, and more and more functions are integrated into the chip to reduce power consumption and cost. There are many kinds of bioelectrical signals, and the common ones include electrocardiogram (ECG), electromyogram (EMG), electroencephalogram (EEG), and electrooculogram (EOG). Several common signals are attached figure...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the problem that passive devices (resistors and capacitors) are difficult to integrate on-chip due to the low low-pass cut-off frequency in the above-mentioned traditional second-order low-pass filter circuit, the present invention proposes a second-order low-pass filter circuit based on current steering technology , by adding two current steering modules to the resistance path of the traditional second-order low-pass filter for current shunting, a lower low-pass cut-off frequency can be obtained while keeping the passive components small enough to achieve low-pass On-chip integration of filters

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