This paper deals with the design and optimization of biquadratic switched capacitor filters for 4th order quadrature-mirror filter banks allowing for real switch effects (e.g. on-state resistance, charge injection¿) and the folded cascode OpAmp designed in 0.35 um CMOS technology. The filter is designed as a cascade of two biquads and each filter is separately optimized using the Differential Evolution Algorithm to obtain the required transfer function with deviation of less than ±0.1 dB from the designed transfer function. The filters process a baseband signals (0-8 kHz) using a clock frequency of 16 kHz. The resulting capacitor values are presented.