Dynamic biasing for an active circuit

摘要

A dynamic bias circuit for an active RF circuit includes an RF sensor coupled to the input port of the active RF circuit to sense the amplitude of the incoming RF signal. A control circuit is coupled to the RF sensor and a bias source. The bias signal to the active circuit is dynamically adjusted by summing the amplitude of the incoming RF signal with the nominal DC signal from the bias source. As the power in the incoming RF signal increase, so to does the bias signal to the active circuit, which allows the active RF circuit to increase its linear range of operation in the presence of stronger signals. The active circuit is designed such that its gain and phase behavior is nearly constant over large bias adaptation ranges without distortion when bias adjustments are dynamically made to the active circuit.

主权项

1. A dynamically adjustable bias circuit for an active RF circuit, the bias circuit comprising:
a broadband radio frequency (RF) sensor having an input port and an output port, the input port of the broadband RF sensor being coupled to an input port of the active RF circuit for sensing a broadband RF signal; a summing circuit in communication with the broadband RF sensor and coupled to the active RF circuit, wherein the summing circuit produces a bias signal for the active RF circuit and increases the bias signal in response to an increase in the broadband RF signal and decreases the bias signal in response to a decrease in the broadband RF signal; wherein the summing circuit has a first input port to receive a nominal direct current (DC) signal, a second input port coupled to the output port of the broadband RF sensor to receive an RF level signal that is representative of an RF power level of the broadband RF signal, and an output port coupled to the active RF circuit, wherein the summing circuit adds the RF level signal to the nominal DC signal to produce the bias signal for the active RF circuit; and a controller coupled to the summing circuit for modifying the nominal DC signal; an RF-power level circuit with an input port coupled to the output port of the broadband RF sensor and an output port coupled to a first input port of the summing circuit, wherein the RF-power level circuit produces an RF level signal that is representative of the RF power level; and a DC level circuit with an output port coupled to a second input port of the summing circuit for providing a nominal DC signal, wherein the summing circuit adds the RF level signal to the nominal DC signal to produce the bias signal for the active circuit.