A reflection type microwave FET oscillator with an impedance converting circuit between the resonant circuit and the FET

摘要

An impedance-converting circuit 8,9,10 is interposed between the FET and the resonant circuit to alter the impedance presented by the resonant circuit, thereby increasing the amplitude of the reflection coefficient of the transistor and ensuring that oscillation occurs. The impedance-converting circuit 8,9,10 may comprise the bonding wire inductance 10, capacitive stubs 9 and an inductive length of microstrip 8. Alternatively, the inductance 10 and the stubs 9 may be formed on the surface of the FET die (figure 8). The capacitive stubs 9 may be omitted (figure 9). The resonant circuit may comprise a length of microstrip coupled to a dielectric resonator. The FET may be in common-drain or common-gate configuration. The output may be microwave or millimetric. The oscillator may be used in a communications transceiver or in radar.