Patent ID: 7366484
Filing Date: 2008-04-29
Classification: H03D

Abstract:
1. A method for dynamically biasing a mixer in a transmitter, comprising: providing a radio frequency (RF) signal to a mixer in a power amplifier control loop, wherein the power amplifier control loop is configured to control output power of a power amplifier located in a transmitter; providing a local oscillator (LO) signal to the mixer, wherein the mixer is configured to mix the RF signal with the LO signal; providing a mixer bias control signal to the mixer, wherein a bias level of the mixer is responsive to the mixer bias control signal; providing a power control signal to a variable gain amplifier in the power amplifier control loop, wherein the power control signal controls output power of the variable gain amplifier; and using a baseband voltage of the power control signal to change an amplitude of a current of the mixer bias control signal using a linear-in-dB function to reduce mixer current in a dB per dB relationship with respect to the output power of the power amplifier during low power operation.