Dynamic Errors of the Switched-Capacitor Discrete-to-Analog Filters in Control and Monitor Systems

Analog low-pass filters (LPF) are used in the input circuits of control and monitor systems (CMS) as pre-processing devices for input analog information and anti-aliasing filters at the ADC inputs to reduce aliasing errors during the time sampling of signals. This article considers the components of the maximum dynamic error of the input circuit of the CMS when using the LPFs based on the switched-capacitors (SC LPF). There are five components of the total dynamic error of the input circuit: a sensor error; an aliasing error; the first class dynamic error; the second class dynamic error; an information delay error in the SC LPF. It is noted that the processes in the input circuits of the SC LPFs are identical to the processes in the sample-and-hold circuits (S/H circuit) of the random-access memories. The attention is drawn to the feature of the SC LPF: the filter itself performs the time sampling of the input signal, which causes the input aliasing error. This must be taken into account.