A Third-Order Integrated Passive Switched-Capacitor Filter Obtained With a Continuous-Time Design Approach

A third-order passive switched-capacitor low-pass filter is presented together with experimental results. The current input-voltage output filter structure realizes complex-conjugate poles although it is composed of switches and capacitors. The results are verified with measurements performed on the filter prototype integrated in a 0.13-
$\mu \text{m}$
CMOS technology. The prototype has a cut-off frequency of 470 kHz, 150-
$\mu \text{W}$
power consumption from 1.2-V power supply, 92-dB SFDR, and an active area of 0.06 mm
²
. The switch-capacitor filter was obtained using a continuous-time model that is also described here and is useful for design, analysis, and simulation of oversampled switched-capacitor circuits. The model is applicable to a variety of topologies including multi-phase passive switched-capacitor filters, switched-capacitor integrators, as well as switched-capacitor dc/dc converters.