The Design of High Performance, High Resolution Two-Order Delta-Sigma Modulator

The design of single loop two-order Delta-Sigma modulator with feed forward structure is presented in this thesis. Oversampled analog-to-digital converters based on second-order delta-sigma modulation are attractive for VLSI implementation because they are especially tolerant of circuit nonidealities and component mismatch. The noise shaping and oversampling are used in this modulator, the oversampling rate (OSR) is 256 and the resolution could be reached 14 bits. The integrally design of Delta-Sigma modulator is argued in deep in the paper, since the behavior model is tested efficiently by Simulink, the time of design has been cut to the bone. As the fully differential structure is used, the system to inhibit the ability of common-mode interference improved and the sampling rate is also raised, the fully differential switching capacity structure is used in the circuit design of modulator. And because of the fully differential structure, the input noise is reduced, the output slewrate of op-amp is greatly improved and the whole circuit is more stable. The 0.5 μm CMOS process is used in simulation of circuit, the results of simulation are shown that the amplifier gain is 82.3 dB, the Phase Margin is 71.34°, the output slewrate of op-amp is 202 V/μs, the unit GainBandWidth is 102 MHz. the whole circuit of modulator is tested with 10.24 MHz of the clock frequency, the SNDR reached to 93.2 dB, the Dynamic Range (DR) is 100 dB. In summary, this Delta-Sigma modulator could be used in Portable, Audio system and so on. Copyright © 2013 IFSA.