System for improving the dynamic range of transmitter power measurement in a cellular telephone

Abstract

An improved power output control circuit is used in a mobile station having a transmitter including a transmitter variable gain amplifier developing an RF output signal applied to an antenna. The improved power output control circuit includes a detector circuit for rectifying an input signal to produce a DC output representing power level of the input signal. A sampling circuit is connected to the transmitter and the detector circuit for alternately connecting and disconnecting the RF signal from the transmitter to the detector circuit, whereby the detector circuit develops an alternating DC output signal. A variable gain AC amplifier is coupled to the detector circuit for amplifying the detector output. A gain control circuit is coupled to the AC amplifier for receiving the amplified detector output and comparing it to a select reference to develop a feedback signal used to vary gain of the AC amplifier to maintain a desired constant output level, the feedback signal representing transmitter output power. A comparator compares the feedback signal to a control reference to control gain of the transmitter variable gain amplifier.

Dependencies are inferred from the claim text.