A Low Distortion FM Tuner Analog Front-End with Multi-tanh Low Noise Amplifier

A CMOS analog front-end (AFE) of a frequency modulation (FM) tuner is presented in this contribution. The proposed AFE consists of a tunable antenna interface and a variable-gain two-stage low-noise amplifier (LNA). The AFE can be tuned to resonate at FM frequencies ranging from 63 MHz to 129 MHz. The LNA achieves a small-signal voltage gain adjustable from -1.5 dB to 30.5 dB across the FM band. By employing the multi-tanh design principle in the LNAs, the linearity of the AFE is improved by 5 dB and 9 dB in the low and high gain modes of the LNA, respectively. The whole AFE is fabricated in a TSMC 0.18-mum CMOS technology. It draws maximum 5.5 mA current from a 1.35-V supply and occupies 0.15 mm² of chip area. Both experimental and simulation results are provided to demonstrate the performance of the AFE.