Design of an integrated CMOS highly sensitive true RMS RF power detector for Cognitive Radio applications

Abstract

A high dynamic range true RMS power detector is designed for broadband frequency agile applications like Cognitive Radio. The RF bandwidth of the Power Detector covers 0.5 GHz – 3 GHz with a dynamic range of 50 dB and a minimum detectable power of −50dBm (50Ω). Its architecture is differential employing a pseudo-differential squaring circuit and it has a high input impedance enabling it to be placed on high impedance as well as on 50Ω lines. Particularly the noise behaviour of the circuit is investigated due to the inherently strong low-frequency noise of the squaring stage. Preamplifier stages, automatic offset cancellation, calibration and oversampling are employed to reach high sensitivity. Logarithmic amplifier stages after the squaring unit care for a linear-in-dB conversion. The power detector has been designed in a commercial UMC 130nm CMOS technology in order to provide easier integration with other mixed-signal blocks and low-cost production.