A Wideband InP DHBT True Logarithmic Amplifier
A wideband logarithmic amplifier is demonstrated in this paper using InP-InGaAs double heterojunction bipolar transistor technology. The amplifier uses cascaded gain stages including the limiting and unity amplifiers to achieve a piecewise approximation to the ideal logarithmic response. The performance of 43-dB dynamic range, 22-GHz bandwidth, and <plusmn2-dB log error is achieved. The integrated circuit consumes 650 mW and has a chip dimension of 1times0.8 mm2