Pacific Monolithics

Fazal Ali

Allen F Podell

Robert H Benton

Sanjay B Moghe

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. By controlling operation of the FETs, different attenuation configurations, such as .pi., T, and double-.pi., are produced as well as different discrete attenuation levels.

Switched low-loss attenuator

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.

Feedback cascode amplifier

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.

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Santa Clara, CA, United States of America

Fazal Ali