A DC-6 GHz, 50 dB dynamic range, SiGe HBT true logarithmic amplifier

In this work, a DC-6 GHz true logarithmic amplifier is presented. The amplifier uses a branch parallel summation architecture with four gain paths, and provides a piecewise approximate logarithmic response. The amplifier has 39 dB gain, 12.5 dB noise figure, 6.5 mV/dB logarithmic slope, and 50 dB logarithmic dynamic range. The amplifier uses Cherry-Hooper gain stages with emitter follower feedback. It also includes an on-chip automatic DC offset error reduction scheme. The circuit was fabricated in a 47 GHz SiGe HBT process. It draws 130 mA from a -3.3 V supply for a power consumption of 430 mW.