Abstract: An electronic device includes an adjustable filter with a first filter element, and a second filter element coupled to the first filter element. The second filter element includes a field effect transistor (FET) including a source terminal, a drain terminal, and a gate terminal. The source terminal and the gate terminal are coupled to a reference voltage. A control circuit is coupled to the drain terminal and is configured to apply a control voltage thereto to vary a capacitance between the source and drain terminals to adjust the adjustable filter.

Abstract: An electronic device includes an adjustable filter with a first filter element, and a second filter element coupled to the first filter element. The second filter element includes a field effect transistor (FET) including a source terminal, a drain terminal, and a gate terminal. The source terminal and the gate terminal are coupled to a reference voltage. A control circuit is coupled to the drain terminal and is configured to apply a control voltage thereto to vary a capacitance between the source and drain terminals to adjust the adjustable filter.

Abstract: RF amplifier bias system for TDMA application. A bias circuit (200) is coupled to an RF power amplifier (201) circuit. The bias circuit includes a charge pump/sink circuit (215) a voltage reference circuit (204) and voltage scaling circuit (208, 210, 214). The bias system provides fast response time when transitioning between various bias voltage applied to an FET RF transistor (244).

Abstract: A system (200) for lossless transmit path antenna switching in a transceiver using quadrature combined power amplifiers is provided. The system is comprised of a quadrature (90°) hybrid power combiner (218) having a first and a second input port (260, 264), an isolated port (266), and an output port (262). The system is also comprised of a first and second RF power amplifier circuit (212, 214). The RF power amplifier circuits are respectively coupled to the first and second input ports. The RF power amplifier circuits have an output impedance that is selectively variable between a first state and a second state. The quadrature hybrid power combiner communicates RF energy from the first and second input ports to the output port when each RF power amplifier circuit is in its first state. The quadrature hybrid power combiner communicates RF energy from the output port to the isolated port when each RF amplifier circuit is in its second state.

Abstract: An apparatus for improved grounding and heat transfer between flange mount field effect transistors and printed wiring boards is provided comprising a cut-out formed in the printed wiring board, extending between its top and bottom surfaces, defining an edge which is covered or plated with a conductive material at least in some areas. One or more vias also extend between the top and bottom surfaces of the cut-out and are exposed along the edge. A field effect transistor is placed in the cut-out and into contact with a heat sink element designed to enhance grounding of the field effect transistor and improve the transfer of heat to the chassis or other metal support structure for the printed wiring board.

Abstract: RF amplifier bias system for TDMA application. A bias circuit (200) is coupled to an RF power amplifier (201) circuit. The bias circuit includes a charge pump/sink circuit (215), a voltage reference circuit (204) and voltage scaling circuit (208, 210, 214). The bias system provides fast response time when transitioning between various bias voltages applied to an FET RF transistor (244).

Abstract: An apparatus for improved grounding and heat transfer between flange mount field effect transistors and printed wiring boards is provided comprising a cut-out formed in the printed wiring board, extending between its top and bottom surfaces, defining an edge which is covered or plated with a conductive material at least in some areas. One or more vias also extend between the top and bottom surfaces of the cut-out and are exposed along the edge. A field effect transistor is placed in the cut-out and into contact with a heat sink element designed to enhance grounding of the field effect transistor and improve the transfer of heat to the chassis or other metal support structure for the printed wiring board.

Abstract: The present invention provides a method and apparatus for design of low loss, size restricted high frequency circuits. In a preferred embodiment, an electronic device includes: a first circuit layer located above the main circuit board comprising a first stripline passive circuit; and a second circuit layer located above the first circuit, the second layer comprising a second stripline circuit. The two stripline circuits can be separately coupled to leads, or coupled to each other and other leads using vias through the ground layer(s) separating each stripline. The stacked stripline elements can be used together with other circuits, and the stacked circuit board can be conveniently joined together with other assemblies, e.g., by surface mounting to a main board. The utility of this topology can be extended by the use of n-circuit embodiment or embedding in a multilayered main circuit board.