Abstract: Apparatus, and an associated method, for radio receiver circuitry operable in multi-modes to receive signals generated during operation of a multiple number of radio communication systems. The receiver circuitry is divided into receive chain portions which are selectably utilized depending upon which of the multiple number of the radio communication systems in which communications are to be effectuated. Selected combinations of the receive chain portions are formed, depending upon which of the modes in which the receiver circuitry is to be operable. Different combinations of the receive chain portions permit sharing of receive chain portions thereby to reduce the required number of circuit elements to form the multi-mode receiver circuitry. In one implementation, the radio receiver circuitry forms the receive portion of a dual-band, tri-mode mobile station operable in a selected one of three different cellular communication systems.

Abstract: A double-.pi. network includes a pair of series resistors connected between input and output terminals. A plurality of FETs of different widths and/or in series with resistors, are each connected in parallel with one of the series resistors. Each FET is controlled jointly with an FET of the same gate size associated with the other series resistor, so that select ones of the FETs, or none may be conducting in parallel with the series in-line resistances. Another plurality of intermediate FETs having gates with different widths, are connected in parallel and separately controllable for coupling selectively the junction between the two in-line resistors to ground. Finally, an additional plurality of pairs of FETs couple the input and output terminals to ground. The FETs making up each pair have gates with the same width and are jointly controllable. The FETs in the different pairs have different widths and/or are in series with different sized resistors.

Abstract: A microwave-frequency feedback amplifier circuit has a cascode amplifier with a first field-effect transistor (FET) having a gate for receiving a signal to be amplified, a source coupled to a reference voltage, and a drain. A second FET has a source coupled to the drain of the first FET, a source coupled to the reference voltage, and a drain. A transformer includes a first inductor with a first terminal coupled to the drain of the second FET and a second terminal for outputting an amplified input signal. A second inductor has a first terminal coupled to the second terminal of the first inductor, and a second terminal coupled to the reference voltage. A feedback circuit couples the drain of the second FET to the gate of the first FET.

Abstract: A monolithic microwave integrated circuit (MMIC) phase shifter is implemented in push-pull configuration with the quadrant selection and vector modulation functions combined. These functions are provided by four sets of adjustable gate-width dual-gate FETs and a pair of lumped element filter networks with a relative differential phase shift of 90.degree..

Abstract: A push-pull monolithic active isloator having a pair of MESFETs in common-gate and common-drain (source follower), parallel configuration. These two FETs are the same size and a diode is inserted between the gate of the source follower and the source of the common-gate FET. A D.C. blocking capacitor is included at the output. Another FET is coupled between the input and ground and responsive to a control signal to vary the current in a biasing resistor between the drain and gate of the source follower.