Digital bias adjustment in a variable supply radio frequency power amplifier

摘要

An RF power amplifier operates over the range of supply voltages provided by a DC/DC converter whether the range of voltages is intentional or unintentional. A system for digitally adjusting the bias levels relative to the supply voltage includes at least one RF power amplifier stage, a digital control block, and a bias circuit. The RF power amplifier stage has at least one RF input signal, at least one RF output signal, and at least one bias input that controls its bias conditions. The RF Power Amplifier Stage includes one or more active gain elements used to amplify the RF input signals. The RF power amplifier operates in a number of bias states controlled by the digital control block. The digital control block uses information related to the supply voltage and may use other information stored in memory to select the desired bias.

主权项

1. A radio frequency (RF) power amplifier comprising:
an RF amplifier stage coupled to receive an RF input signal and supply an RF output signal, the RF amplifier stage including one or more active gain elements to amplify the RF input signal, the RF amplifier stage being further coupled to a variable supply voltage and to one or more bias signals to set a bias state for the RF amplifier stage; a bias circuit coupled to receive a control input specifying the bias state, the bias circuit coupled to supply the one or more bias signals to the RF amplifier stage, operation of the RF amplifier stage being varied in response to change in the bias state; a sense circuit coupled to the variable supply voltage, the sense circuit operable to produce a digital representation of the variable supply voltage and supply the digital representation as a digital sense input; and a digital control block coupled to receive the digital sense input representing the variable supply voltage, the digital control block operable to determine the bias state for the RF amplifier stage responsive to the digital sense input, the bias state varying according to the variable supply voltage, the digital control block coupled to the bias circuit to provide the control input.