Design Consideration for LC Analog Filters: Inductor ESR Compensation, Mutual Inductance Effect and Variable Center Frequency

This paper presents several considerations of LC analog filter design. First, we propose an inductor equivalent series resistance (ESR) compensation technique for LC analog band-pass filters (BPFs) and band-elimination filters (BEF) for low-cost analog/mixed-signal IC test systems. The proposed technique uses an instrumentation amplifier and a few resistors. Also, the technique can be extended to the variable inductor implementation for variable center frequency. They were verified with simulation and measurement results. Further, we show in simulation and experiment that mutual inductance between two inductors in the BPF degrade its stop band characteristics, and this problem can be alleviated by the perpendicular placement of the inductors.