Closed Loop Frequency Control for Tunable High Quality Factor Filters

To address DARPA need to overcome the growing problems of co-site interference encountered in the modern military communications systems, RST Scientific Research, Inc. ("RST") proposes to develop a new low size, low cost low power closed-loop controlled high-Q frequency agile filter-bank assembly with RF channel select capability from 20 MHz to 30 GHz. The new filter-bank design to be inserted in line between the antennas and the receiver front-ends uses a digitally activated control to select and optimize the signal-to-interference (S/I) ratio enabling continuous detection of signal of interest (SOI) in the presence of co-site interferences. In addition, the new design possesses the ability of dynamically changing bandwidth, center frequency in microsecond range tuning response time. The filter-bank assembly provides suppression of undesirable signals by 30 dB min. (without significantly impacting the receiver noise figure) anywhere within the operating communication bands. The digital closed-loop-control design also maintains continual long term center frequency and bandwidth stability by precise voltage control capability. In Phase I, RST will establish the design feasibility by computer simulations and by testing a subscale prototype. In Phase II, RST plans to develop a fully-functional prototype unit that will be implemented and tested in the realistic scenarios.