CMOS RF power amplifier with LDMOS bias circuit for large supply voltages

摘要

Bias circuitry that may be used within a communications or other device includes a first current mirror having first and second transistors with sources coupled to ground and operable to receive a reference current at a drain of first transistor. A second current mirror has first and second transistors with drains coupled to a battery voltage supply. A third current mirror has first and second transistors with drains coupled to sources of the first and second transistors of the second current mirror, respectively. A biasing transistor couples between the second transistor of the first current mirror and the first transistor of the third current mirror and operable to receive a tuning input voltage at its gate. A resistive element coupled between the second transistor of the third current mirror and ground produces a bias voltage produced at a connection of the resistive element and the second transistor of the third current mirror.