Realization of Fully Differential Fourth-Order Chebyshev Filter with Tunable Frequency
全差分可调频率四阶Chebyshev滤波器的实现

A fully differential R-MOSFET-C fourth-order Chebyshev filter employing fully differential operational amplifier, passive resistors and current-steering MOS transistors is proposed, this proposed implementation relies on the tunability of current-steering MOS transistors in the triode region acting as variable resistors in order that the cutoff frequency of the filter could be tuned continuously, the amplifier is not only with voltage common-mode negative feedback, but also with current common-mode negative feedback, which will benefit for the stability of its dc operating point, the filter whose cutoff frequency range is from 20kHz to 420kHz, demonstrates better than 65dB THD with 100kHz, 2.5Vpp input signal in Taiwan UMC 2P2M(2-Poly, 2-Metal) 0.5pm CMOS technology, the filter measures 0.36mm2, and consumes only 16mW from a single 5.0V power supply.