System and method for an electronically tunable frequency filter having constant bandwidth and temperature compensation for center frequency, bandwidth and insertion loss

Abstract

A novel system and method for a frequency tunable filter is described. The inventive system and method may be used, for example, in multi-band cellular phones and/or transceivers in wireless networks. The inventive system and method avoids the creation of undesired spurs thus minimizing design difficulties and obviating the need for complex multiple frequency conversions and the associated deleterious effects on performance. The inventive system and method provides at an output terminal an output signal at one of a plurality of predetermined frequencies. The inventive system and method comprises input circuitry for providing an input signal that is at least in part a function of a dynamic parameter, a processor for providing a control signal as a function of said input signal, and at least one adjustable resonance circuit capable of providing a filter signal at one of a plurality of predetermined frequencies in response to said control signal, wherein said filter signal is applied to said output terminal to thereby provide said output signal at one of a plurality of predetermined frequencies. The present inventive system and method also provides for reducing spurious signals from a composite signal created from mixing a plurality of signals by filtering the composite signal.