A 18-33 GHz Variable Gain Down-Conversion Mixer in 0.13µm SiGe:C BiCMOS technology

This paper presents a high gain, high bandwidth (BW) variable gain downconversion mixer operating from 18-33 GHz RF frequency in the 0.13µm SiGe:C BiCMOS technology. The mixer core is based on micromixer topology, which needs a single-ended RF signal thus eliminating the need for additional balun at the input. The resistive loads were replaced by active PMOS loads with common-mode feedback (CMFB) resulting in higher conversion gain and low power consumption. The gain of the mixer is controlled by NMOS transistors operating as a variable resistor without any additional power consumption. Thus the variable-gain amplifier (VGA) can be eliminated from the receiver to reduce power consumption. The mixer gain ranges from -10 dB to 15.5 dB. Due to the elimination of the input balun and area consuming inductor, the mixer consumes a very small chip area of 310×216µm2 excluding the bond pads. The down-conversion mixer has a maximum input 1dB compression point (IP1dB) of -10 dBm, only limited by the linearity of the output buffer. The presented mixer provides high gain with variable gain function and moderate linearity while consuming a very small chip area compared to the state-of-the-art mixers in this frequency range.