Patent ID: RE42604

Claim:
A multimode transceiver circuit, comprising: a) a four port coupler for splitting an input signal into split signals which are phase shifted by a known amount, the coupler having a first port for receiving the input signal and for outputting an output signal therefrom; b) a controllable oscillator connected to a second port of the coupler; c) switchable impedances connected to the remaining ports of the coupler; and d) control means for controlling operation of the oscillator and the impedances such that: i) in one mode of operation, the oscillator is inoperative, and at least one of the impedances is switched to operate as a non-linear impedance to detect amplitude modulation of the input signal applied to the first port, ii) in a further mode of operation, the oscillator is operable, and the impedances are switched to operate as non-linear impedance elements to operate as a mixer to produce an intermediate frequency signal in dependence on the input signal applied to the first port, and iii) in yet a further mode of operation, the oscillator is operable, and the impedances are switched such that an oscillator frequency appears at the first port for transmission therefrom.