Research of a Filter on Switchable Capacitors with Three-Phase Control of Electronic Keys

A low frequencies filter of the second order on switched capacitors has been developed and studied, the distinctive feature of which is three-phase control of three electronic keys. In the proposed circuit, this allows, at constant parameters of the frequency-setting capacitors and a fixed switching frequency of electronic keys, to control the frequency of the filter pole by changing the ratio of the resistances of resistors in the general feedback circuit. The basic equations for the filter transmission coefficients at zero frequency and at the pole frequency are given, as well as formulas for calculating the pole frequency and pole attenuation at the second order. A simulation of the filter was made in the Micro-Cap environment, which shows that the considered circuit solution performs the functions of a low-pass filter. Considered filter on switched capacitors can be used to create new adaptive measuring systems and analog-digital signal processing devices.