A 10 mW LNA with Temperature Compensation for 24 GHz Radar Applications in SiGe BiCMOS

This paper presents a low-power, two-channel, ESD-protected 24 GHz single-ended input to differential output single-stage cascode LNA with temperature compensation in Infineon's SiGe BiCMOS technology. We propose a circuit technique to reduce LNA performance variation over a wide temperature range by providing bias current with an optimal slope. This bias current is obtained by a weighted combination of PTAT current and reference current with zero temperature coefficient. The resulting circuit shows in measurement reduction of gain variation from 4.4 dB to 1.3 dB over the automotive temperature range −40 to 125°C. Additionally, the circuit offers two gain settings with a 6 dB step. To reduce power consumption, the circuit operates from a low supply voltage of 1.5 V. At the center frequency of 24 GHz the amplifier offers a gain of 14.4 dB and a noise figure of 2.7 dB including the on-chip input balun. The circuit exhibits linearity of −11.8 dBm input-referred 1dB compression point at 24 GHz. Single LNA channel consumes only 7 mA from a single 1.5 V supply. The circuit exhibits a 6 kV HBM hardness at the input RF pin. The chip size including two LNA channels and the pads is 0.93 mm2.