Radio‐frequency amplifier with tunable high‐Q RF bandpass filtering for SAW‐less wireless receivers

An inductor‐less on‐chip radio frequency bandpass filtering (RF‐BPF) technique with tunable centre frequency is proposed to replace the bulky and expensive external SAW filter. The centre frequency of the BPF not only tracks the local oscillation (LO) frequency ( f LO ), but also can be shifted from f LO to a controllable offset for low‐IF applications. The RF‐BPF has been embedded into a single‐ended‐input differential‐output radio frequency amplifier (RFA) and implemented in 65nm CMOS. The RFA draws 3.5 mA DC current from a 2.5 V power supply. Measurement results show that the BPF achieves 16 dB attenuation at 150 MHz offset from the 1.5 GHz centre frequency, and 7 MHz tunable range without changing the LO frequency.