8 GHz high conversion gain Darlington mixer

This paper describes a new Darlington AC-coupled mixer operating at 8 GHz with improved figure-of-merits. This Darlington AC-coupled mixer along with a simple AC- coupling mixer used for reference are implemented in a 0.35 mum SiGe bipolar process. The supply voltage and current consumption are 3.2 V and 28 mA. In the Darlington AC-coupling mixer, the conversion gain, the operating bandwidth, and the NF are found to be improved by 13 dB, 180 MHz, and 10 dB, respectively. These improved figure-of-merit results from the use of the Darlington cell in the transconductance stage of the AC-coupling mixer.