A 7GS/s Complete-DDFS-Solution in 65nm CMOS


IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.4   pp.206-217
Publication Date: 2018/04/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E101.C.206
Type of Manuscript: Special Section PAPER (Special Section on Solid-State Circuit Design — Architecture, Circuit, Device and Design Methodology)
complete-DDFS-solution,  high-speed DDFS,  CMOS,  RDAC,  RSTC-DEM,  rail-to-rail operation,  two-times interleaved,  

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A 7GS/s complete-DDFS-solution featuring a two-times interleaved RDAC with 1.2Vpp-diff output swing was fabricated in 65nm CMOS. The frequency tuning and amplitude resolutions are 24-bits and 10-bits respectively. The RDAC includes a mixed-signal, high-speed architecture for random swapping thermometer coding dynamic element matching that improves the narrowband SFDR up to 8dB for output frequencies below 1.85GHz. The proposed techniques enable a 7 GS/s operation with a spurious-free dynamic range better than 32dBc over the full Nyquist bandwidth. The worst case narrowband SFDR is 42dBc. This system consumes 87.9mW/(GS/s) from a 1.2V power supply when the RSTC-DEM method is enabled, resulting in a FoM of 458.9GS/s·2(SFDR/6)/W. A proof-of-concept chip with an active area of only 0.22mm2 was measured in prototypes encapsulated in a 144-pins low profile quad flat package.