Narrow-band MMIC filters with automatic tuning and Q-factor control

Abstract

Fully integrated, narrowband, tunable active filter monolithic microwave integrated circuits (MMICs) have been demonstrated at X-band. The three-section bandpass chip had a minimum insertion loss of less than 1.5 dB and a -3 dB bandwidth of 3% at 8.4 GHz. The notch filter chip exhibited a minimum -30 dB notch bandwidth of 20 MHz and a 2.7-GHz tuning range. A master-slave filter control circuit with fully integrated RF components was shown to track a reference signal over a frequency range greater than 2.5 GHz while maintaining the slaved filter notch depth at greater than 25 dB over that band. The same control circuit virtually eliminated the temperature dependence of the notch depth and provided a five-fold reduction in the notch frequency drift.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>