Temperature compensated voltage tunable circuits using surface wave devices

Abstract

Abstract Electrical circuits which are sensitive to frequency drift with temperature changes are stabilized by employing a matched pair of surface wave devices; the first having a negative temperature coefficient Alpha 1; the second having a positive temperature coefficient Alpha 2. An oscillator circuit is temperature compensated by inserting a matching pair of surface wave delay elements in the feedback loop and choosing the delay time so that Alpha 1t1 - Alpha 2t2, where t1, t2 are the delay times provided by the delay elements having temperature coefficients Alpha 1, Alpha 2. A first oscillator circuit comprises a single amplifier and a pair of matched surface wave delay elements coupled in tandem in the feedback loop. A second oscillator circuit comprises a pair of amplifiers and a pair of matched surface wave delay elements alternately coupled in a closed loop configuration so that the delay elements are interlaced with the amplifiers. In a receiver system having a mixer, a local oscillator, and an IF filter for converting RF input signals to IF output signals, temperature compensation is achieved by employing a surface wave delay element in the local oscillator feedback loop and a surface wave integratable filter as the IF filter and choosing the temperature coefficients and local and intermediate frequencies so that Alpha LOfLO - Alpha IFfIF, in systems where fLO<fRF and Alpha LOfLO Alpha IFfIF when fLO>fRF, where Alpha LO'' Alpha IF are the temperature coefficients of the delay element and filter, respectively, and fRF, fIF and fLO are the RF intermediate and local oscillator frequencies, respectively. The oscillator circuits are voltage tuned by providing an intermediate electrode on the active surface of a surface wave delay element and impressing a DC signal or an AC signal or a combination of both between the intermediate electrode and the ground plane of the delay element.

Inventors

• 👤 Donald B Armstrong

Bibliographic Details