Active GaAs MMIC band-pass filters with automatic frequency tuningand insertion loss control

This paper presents the design and measured performance of active tunable band-pass MMIC filters and matched MMIC control circuits, both fabricated using a standard 1-μm GaAs MESFET foundry process. The control circuits generate filter frequency-tuning and Q-control bias voltages by using a dual-loop master-slave control scheme. Separate 3-section filters cover 1.5-2.0 and 1.96-2.64-GHz bands with 3-dB bandwidths of 86±6 and 126±1.0 MHz, respectively. The control circuits automatically maintain the filter insertion loss to within ±0.5 dB over these tuning ranges, and regulate the center frequency and insertion loss to within better than ±1.2 MHz and ±0.3 dB over a temperature range of -50°C to +75°C