Ultra high-Q on-chip RF inductor and bandpass filter design based on active magnetic energy recovery (AMER)

Future RF system-on-chip designs require high performance reactive components—particularly on-chip inductors. It is desirable for inductors to have low loss, and consequently high quality factor (Q). Conventional planner passive spiral inductors exhibit very limited Q, thus forcing BPFs to be implemented by off-chip SAW and ceramic components.; Previously developed on-chip active inductors, such as gyrators, were implemented via impedance transformation. However, due to difficult issues in power, noise, linearity and reproducibility, gyrators have not been popular in RF circuit design. To alleviate these problems, we have developed on-chip high-Q inductors by using active magnetic coupling.; 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 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 analytic model of the inductor will be discussed first, following by the measurement result. Two types of BPFs at different bands through different approach will be also shown.