A Four-Channel Beamforming Down-Converter in 90-nm CMOS Utilizing Phase-Oversampling

作者：Tseng Richard^*; Li Hao; Kwon Dae Hyun; Chiu Yun; Poon Ada S Y

来源：IEEE Journal of Solid-State Circuits, 2010, 45(11): 2262-2272.

DOI：10.1109/JSSC.2010.2063971

• Beamforming
• Cartesian combining
• dynamic range
• mixer
• multiphase local oscillator (LO)
• phased arrays
• phase-oversampling
• phase shifter
• RF CMOS
• receivers
• RF variable gain amplifier (RFVGA)
• vector modulator (VM)

In this paper, a 4-GHz, four-channel, analog-beamforming direct-conversion down-converter in 90-nm CMOS is presented. Down-converting vector modulators (VMs) in each channel multiply the inputs with complex beamforming weights before summation between the different channels. The VMs are based on a phase-oversampling technique that allows the synthesis of inherently linear, high-resolution complex gains without complex variable gain amplifiers. A bank of simple passive mixers driven by a multiphase local oscillator (LO) in each VM performs accurate phase shifting with minimal signal distortion, and a pair of transimpedance amplifiers (TIAs) combines the mixer outputs to perform beamforming weighting and combining. Each individual channel achieves 360 degrees phase shift and gain-setting programmability with 8-bit digital control, a complex gain constellation with a mean error-vector magnitude (EVM) of <2%, and a measured phase error of < 5.5 degrees at a back-off of 4 dB from the maximum gain setting. The beamformer demonstrates >24-dB blocker rejection for blockers impinging from different directions and 17-dB signal EVM improvement in the presence of an in-channel blocker.

• 出版日期2010-11
• 单位中国科学技术大学