On-chip RF spiral inductors and bandpass filters using active magnetic energy recovery

We present designs to achieve monolithic integration of high-Q spiral inductors and bandpass filters (BPFs) in standard CMOS technology. The designed transformer-type inductor behaves like an ideal inductor due to the active magnetic feedback from the secondary coil for compensating energy loss in the primary coil. This approach is compatible with mainstream IC technologies and has potential to achieve high-Q reactance with low power, low noise and high linearity. The fabricated inductors exhibit Q/spl sim/3000 between 1.5 to 2.1 GHz. The fabricated BPF shows 3 dB bandwidth of 120 MHz at 1.75 GHz with 3.1 dB in-band gain and 30 dB out-of-band rejection below 1.2 GHZ.