A Broadband Logarithmic Power Detector Using 130 nm SiGe BiCMOS Technology

This work presents the design of a broadband logarithmic (log) power detector implemented using 130 nm SiGe BiCMOS technology. The proposed log detector uses a pair of common-emitter SiGe HBTs for sensing, and a log amplifier stage is employed to achieve linear-in-dB transfer characteristic. The log detector shows 23 dB dynamic range with -28 dBm minimum input power from 2 GHz to 40 GHz with +/- 1.5 dB log error. The design consumes 3.2 mW of static DC power with a 2-V supply and consumes less than 7.8 mW of DC power over the input power range. A two-branch log detector design consisting of two identical parallel log detectors with modified output stage is also presented. The two-branch log detector demonstrates 47 dB dynamic range with minimum input power of -53 dBm at 10 GHz with +/- 1.5 dB log error, with an externally introduced 25 dB power level offset between the inputs of the two branches.