A 2.7V, 1.8GHz, 4th order tunable LC bandpass filter with ± 0.25dB passband ripple

A low-voltage 4th order RF bandpass filter structure based on a two magnetically-coupled resonators prototype is presented. Each resonator is built using on-chip spiral inductors and accumulation-mode PMOS capacitors to provide center frequency tuning. The proposed architecture is using electric coupling to emulate the effect of the transformer thus providing bandwidth tuning with small passband ripple. The filter has been implemented in HP0.5 µm CMOS process and occupies an area of 0.15mm². It consumes 16mA from a single 2.7V supply at a center frequency of 1.84GHz and a bandwidth of 80MHz while providing a passband gain of 9dB. The measured output 1 dB compression point, and output noise power spectral density are -40dBm and -161dBm/√Hz, respectively. This results in a 1dB compression dynamic range of 42dB.