Reconfigurable Bandpass Filter Using SLCFET Technology

We report on the successful fabrication and demonstration of a low loss, high performance reconfigurable bandpass filter technology. A digitally reconfigurable bandpass filter was implemented by placing the low pass and high pass reconfigurable filters in series. Reconfigurable low pass and high pass filters were implemented by combining MMICs with RF switches selecting capacitor values and off chip high Q fixed inductors. The same circuitry was implemented in both a commercial GaAs pHEMT process as well as Northrop Grumman’s GaN based SLCFET technology. The resulting reconfigurable bandpass filter operates between 1.0-2.0 GHz, with over 500 different filters selections and supporting variable center frequencies as well as variable bandwidth sizes ranging from 70 MHz to 100 MHz, all in a single device. Depending on the center frequency and bandwidth of the selected path, the SLCFET based switched reconfigurable filters demonstrated a NF and insertion loss improvement over the GaAs variant by > 2 dB, while demonstrating an P1dB
average
of 33.6 dBm, compared to an average P1dB
average
= 17.8 dBm power handling of the GaAs reconfigurable filter. The SLCFET based filter was measured as having 20x greater linearity than the GaAs filter, with the average two tone IIP3 for the SLCFET filter at 43 dBm, compared to 30 dBm for the GaAs design.