A S/C/X/Ku-band, 4-Tap, Digitally Controllable Analog FIR Filter with Reconfigurable Bandwidth and RF Filtering Profile

A proposed wideband integrated 4-tap analog finite impulse response (AFIR) filter has been implemented in silicon germanium (SiGe) technology for use in direct-throughput of RF signals in the microwave and millimeter-wave spectrum. To simultaneously provide bandwidth and RF filtering profile tunability, a wideband coefficient/polarity control circuit and time delay elements are utilized. The proposed 4-tap AFIR filter consists of coefficient/polarity/tap control circuits with equalization, time delay elements, wideband Wilkinson power divider/combiners, a two-stage low-noise amplifier (LNA) with equal power distribution, and an active power combiner. The proposed AFIR filter addresses flat in-band response, low-pass filter (LPF), high-pass filter (HPF), and notch filter depending on coefficient and polarity control sets. To provide simple system configuration and a high integration level for a multi-tap AFIR system, all required coefficients, polarities, and taps are controlled by digital control units.