A 245 GHz LNA in SiGe Technology

A five-stage differential SiGe low noise amplifier (LNA) in cascode topology is presented. Transformer coupling is used between the stages to obtain inter-stage matching. The single ended input and output of the LNA are realized by baluns. The LNA has 18 dB of gain at 245 GHz and a 3 dB bandwidth of 8 GHz. A noise figure of 11 ±1 dB NF of the LNA at 245 GHz was measured by the Y-factor method. These values represent the highest gain and the lowest measured noise figure at 245 GHz reported for a SiGe LNA so far. The LNA draws 82 mA at a supply voltage of 3.7 V.