A Low-Power Low-Noise Decade-Bandwidth Switched Transconductor Mixer With AC-Coupled LO Buffers

In this paper, a modified switched transconductor mixer structure is proposed to realize a low-power, low-noise, and wideband mixer, in which, a transconductor stage with fixed dc operating point is switched by the ac-coupled local oscillator (LO) signal. In this way, only a small LO signal is required to turn the transconductor ON and OFF, and thus a low-power LO buffer can be used to achieve wideband down-conversion. To further expand the bandwidth, the inductive peaking technique is used at the RF port to eliminate the capacitive loading effect resulted from the input transistors. As the noise power from LO stage appears in common mode at the mixer output, good noise performance is realized, too. Additionally, output distortion-cancellation IF buffer is added to facilitate the testing. Fabricated in the 0.13μm CMOS process, 15.5-17.5-dB gain and 4-5.2-dB noise figure are achieved in 1-10-GHz bandwidth. The mixer core consumes a low power of 8.3 mW from 1.5-V supply, and the whole chip consumes 22.3 mW, including the IF buffer. The active chip area is less than 0.2 mm
²
.