A 73.1dB SNDR Digitally Assisted Subsampler for RF Power Amplifier Linearization Systems

• Main Authors: Chung, SungWon (Contributor), Dawson, Joel L. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science (Contributor), Massachusetts Institute of Technology. Microsystems Technology Laboratories (Contributor)
• Format: Article
• Language: English
• Published: VLSI-TSA, 2011-01-07T21:44:17Z.
• Subjects: Article
• Online Access: Get fulltext

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We present a digitally assisted subsampler, designed to serve as the downconversion path in adaptive predistorters for 800MHz-5.8GHz RF power amplifiers. We use digital averaging to overcome the noise folding problems of subsampling, obtaining a final SNDR of 73.1dB for signals centered about a 2.4GHz carrier. Using quadrature subsampling, we obtain both the I and Q samples from the same physical path and thereby eliminate IQ gain mismatch. When used as part of an adaptive predistortion system, the subsampler enables an EVM improvement of 3.2% and distortion products suppression of up to 7.6dB for 802.11g signals. The subsampler IC, designed in a 90nm CMOS process, consumes 6.0mW from a 1.2V supply.
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