A new fourth-order Gm-C CMOS polyphase filter for Low-IF receiver

A new CMOS Gm-C polyphase filter for Low-IF receiver is presented. As the linearity of the Gm-C polyphase filter is determined by the transconductor amplifier, a highly linear transconductor amplifier is designed. A novel Gm-C polyphase filter topology is proposed to reduce the die area. The center frequency of the novel 4thorder Gm-C polyphase filter is 2.5MHz with the bandwidth of 3.6MHz. Designed in 90nm standard CMOS process; the polyphase filter occupies only 0.0465mm2. Consuming 1.02mA from a 2.4V voltage, the polyphase filter achieves a voltage gain of 6.85dB at the pass-band and an image rejection of 31.5dB at -2.5MHz.