A CMOS gm-C polyphase filter with high image band rejection

This paper presents a 7th order polyphase (14th order bandpass) gm-C IF filter implemented in a 0.35 µm CMOS process. The filter bandwidth is 1 MHz, the center frequency is 3 MHz, the image band rejection is higher than 53 dB, the stop band attenuation is at least 40 dB, and the in-band group delay variation is 0.5 µs. The noise floor is 170 µVrmsand the spurious free dynamic range is at least 59 dB for out-of-band signals. Current consumption is 3.2 mA from a 2.3 V power supply. The filter is well suited for employment in the Bluetooth short-range radio.