Sallen-Key Dual Channel Low-Pass Filter with Tunable Cutoff Frequency

Abstract

A two-channel Sallen-Key low-pass filter on three non-inverting amplifiers is studied, which has the property of unrelated digital set of the upper cut-off frequency at constant index of the transmission coefficient in the bandwidth range. The restructuring of the upper cutoff frequency and the attenuation of the pole is carried out by modify the resistors’ resistance of one in the upper channel of the low-pass filter. It is shown that a non-inverting amplifier in the lower channel of the low-pass filter can have a small value of the systematic zero bias voltage component, what is important for the operation of the low-pass filter at the input of analog-to-digital converters. It has been established that due to the construction of a low-pass filter according to a two-channel architecture, the requirement for the magnitude of the output static voltage of the upper channel is removed. The base equations of the new low-pass filter scheme are given and the summary modeling in the Micro-Cap was pictured.