A 10–67 GHz 1.44 mW 20.7 dB Gain VGA-Embedded Downconversion Mixer With 40 dB Variable Gain Range

A high gain low power variable gain downconversion mixer is presented here. In a conventional mixer, its conversion gain is limited by the load impedance due to limited voltage supply. In addition, accurate conversion gain control is challenging due to DC-offset and various parasitic effects. By using a negative resistance to negate the load resistance and implementing a dc free variable resistor across the output, the seemingly fundamental limitation mentioned above can be eliminated. This way, high gain mixer with controllable variable gain can be achieved at low voltage supply. Thus, variable-gain amplifier (VGA) can be removed in a receiver to save power. The measured conversion gain is 16.5 to 20.7 dB over the operation frequency of 10 to 67 GHz. Furthermore, the measured variable gain range is 40 dB at 24 GHz. To the best of the authors' knowledge, this is the first millimeter-wave (mm-wave) variable gain CMOS mixer ever reported. In addition, this work also demonstrates the highest conversion gain among all CMOS mm-wave active mixers with the least power consumption.