A Time-Interleaved $DeltaSigma$-DAC Architecture Clocked at the Nyquist Rate

This paper describes a delta–sigma ( $DeltaSigma$) digital-to- analog converter (DAC) architecture that combines a polyphase decomposition of the interpolation filter and a time-interleaved error-feedback $DeltaSigma$ modulator. Noise-shaped oversampling is achieved while clocking the digital circuitry at the Nyquist rate. The design of a third-order 4-bit modulator with eight times oversampling using the architecture is presented. Results from a prototype current-DAC driven by a VHDL simulation of the digital design at 2.66 GHz show that 56-dB linearity is achievable in 90-nm CMOS within a 1-V supply over a 155-MHz signal bandwidth making the architecture suitable for emerging ultra-wide-band and 60-GHz radio applications.