PIN diode-based 4-channel switched filter bank with low-power, TTL-compatible Driver

The design of a 4-channel switched filter bank in the S-, C-band using PIN diode switches is described. Narrow band (3.2-3.5%) filters are designed on suspended substrate stripline. The biasing circuit allows the switches to be driven with TTL-compatible voltages and minimum biasing current. The average insertion loss measured was 3.6 dB corresponding to a Q-factor of 580. Spurious responses were suppressed from DC to roughly 19 GHz.