Abstract: According to the apparatus of the present disclosure, dual gate control and dual gain control uses variable voltages on the gates of first stage (302) and a second stage (304) to control the output power. In alternate embodiments, dual drain control is also employed using a variable voltage supply on the drains of the first stage (302) and the second stage (304). In particular, a level shifter circuit (421) is employed to convert a positive voltage gate control signal to negative voltage with respect to ground. Drain current limiting circuits (417, 419) are used to sample drain currents and generate gate voltages to maintain a desired current ratio between stages of a multi-stage amplifier. When dual drain control is also employed, a 1:1 ratio of drain control voltages is employed at low power levels, with a single drain control at higher power levels.

Abstract: According to the method and apparatus of the present disclosure, dual drain control uses a variable voltage supply on the drains of a first stage (302) and a second stage (304) to control the output power. In particular, dual drain control having a 1:1 ratio is employed at lower power levels, with single drain control at higher power levels. Such drain control could be employed by directly varying (1008, 1010) the voltage on the drains of the power amplifier, such as with signals from a microprocessor, or by a specific circuit (203) to generate the drain voltages based upon a control voltage.

Abstract: A transmitter (135) responds to a first control signal by outputting a transmit signal at a transmit power according to the first control signal. A power-level detector (149) responds to the transmit power by outputting a second control signal representative of a power level of the transmit power. A sensing network (159) is capable of changing from one state to another state in response to a stimulus, for example, the position of a retractable antenna (101) or attachment of a connector (113) or both. The sensing network may modify the second control signal depending upon the state of the sensing circuit. A controller (161) responds to the second control signal, whether modified or not, by determining the first control signal according to the second control signal.