Skyworks Solutions, Inc.

Conexant Systems, Inc.

Thomas L Fowler

Andre G Metzger

Amish Naik

Hugh J Finlay

Mark Bloom

According to one exemplary embodiment, a circuit arrangement includes a power amplifier configured to receive an RF input signal. The circuit arrangement further includes a control circuit configured to receive and convert the RF input signal to an output DC voltage. The control circuit includes a voltage amplifier coupled to a peak detector circuit, where the peak detector circuit outputs the output DC voltage. The circuit arrangement further includes an analog control bias circuit coupling the output DC voltage to a bias input of the power amplifier. The output DC voltage causes the power amplifier to have a quiescent current that increases in a way that is substantially logarithmic with respect to the amplitude of the RF input signal. An increase in the RF input power can cause a substantially linear increase in the output DC voltage, where the RF input power is measured in dBm.

Circuit for controlling power amplifier quiescent current

Quiescent current control circuit for power amplifiers

The bias control selectively provides for bias of a power amplifier based upon a bandgap voltage generated by the bias control, or by a bias voltage external to the bias control. A controller controls the selection of either the bandgap voltage or external bias voltage. The bias control is fabricated in a first semiconductor material capable of operating at low voltage supply levels, such as complementary metal oxide semiconductor (CMOS) material and may be fabricated on an integrated circuit common with a power amplifier.

Configurable power amplifier and bias control

Two compensating resistors in a mirror bias circuit coupled to a radio frequency (RF) amplifier are configured such that transistor base-emitter voltages are adjusted to stabilize RF transistor quiescent current for variations in collector voltage, Vcc. For example, when battery power is drained during device use, Vcc decreases. As Vcc decreases, less current is drawn through the compensating resistors, thereby decreasing the voltage drop across the compensating resistors and increasing the transistor base-emitter voltages in the mirror bias circuit and the radio frequency (RF) amplifier. Thus, the tendency of the RF transistor quiescent current to decrease as Vcc decreases is off-set because the compensating resistors cause an increase in the RF transistor base-emitter voltage, thereby increasing quiescent current. In one embodiment, the first compensating resistor size is equal to the second compensating resistor size multiplied by the ratio of the buffer transistor current rating to the mirror transistor current rating.

Growing community of inventors

Moorpark, CA, United States of America

Thomas L Fowler