Temperature compensated wide dynamic range power detection circuitry for portable RF transmission terminals

摘要

A detector for a portable telephone or the like samples RF transmit power, detects the sampled signal using a Schottky diode and uses a logarithmic amplifier to apply a compressive function to the post- detection signal. The compressive function emphasizes power level changes at the low end of the transmission spectrum and de-emphasizes power level changes at the high end of the transmission spectrum. In this way, the range of detected powers required to be processed by subsequent circuitry is reduced, thereby simplifying the design of the circuit. To improve stability of the detector with respect to temperature fluctuations, the semiconductor element in the amplifier which provides its logarithmic characteristics is temperature- compensated, as is the detector diode.