A new scalable non-feedback ΔΣ digital-to-analog converter

This paper describes a new noise-shaping D/A-converter which in opposite to the conventional ΔΣ modulator has no global feedback. The proposed topology is well suited for a pipelined clocking scheme which leads to increased oversampling ratios for both first and higher order modulators. The maximum clock-frequency of the new modulator is limited only by the delay through one single accumulator regardless of modulator order, which represents a huge saving compared to the conventional modulator. The converter is very modular and scales easily to higher modulator orders. Still the proposed topology is mathematically equivalent to the classical ΔΣ-modulator. Theoretical analysis and circuit simulations for a first-order converter are presented. The circuit has been implemented in a FPGA-circuit from Altera and measured results are presented.