A Low-Power Ultra-Wideband RMS Power Detector for Power Amplifier Control Loop

This paper presents a low-power ultra-wideband RMS power detector fabricated in CMOS 55 nm process. The square-law characteristic of MOS transistor is exploited to convert RF power information into DC voltage. The circuit is composed of an RMS detection module and a closed-loop operational amplifier, which are utilized for power signal conversion and DC voltage amplification, respectively. The closed-loop two-stage operational amplifier features adjustable feedback and pull-up/pull-down resistors, allowing for flexible adjustment of power detection range. According to the measured results, the maximum dynamic range is 20 dB for 2-18 GHz RF input signals. With a supply voltage of 1.2 V, the power consumption is only 0.9 mW, and the differential output exhibits rail-to-rail range.