A high-level simulation and synthesis environment for ΔΣ modulators
IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
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An equation-based behavioral model has been developed to predict the real performance of a single-loop single-bit Sigma Delta Modulator SDM. By using this prediction flow, not only can the circuit specifications be acquired, including the gain, bandwidth, slew rate of the OPAMPs, and the capacitor value in the switched-capacitor circuits, but the real performance of the SDM can also be predicted. The switched-capacitor circuits according to the required circuit specifications are employed to design a fourth-order feed-forward FF SDM with an over-sampling ratio OSR of 64 and a bandwidth of 10kHz using a TSMC 0.35ï戮µm CMOS process. The measurement results reveal that the SDM with an input frequency of 2.5kHz and a supply voltage of 3.3V can achieve a dynamic range of 90dB and a spurious-free dynamic range SFDR of 85dB under the signal bandwidth of 10kHz and a sampling frequency of 1.28MHz, respectively. The precision of the equation-based behavioral model has been validated by experimental measurements, and its inaccuracy is less than 4%.