Based On 16 Sampling Sigma-delta Noise Shaping Dac Design And Vlsi Implementation

Sigma-Delta conversion technology is based on oversampling, noise shaping.There are many inherent advantages in S-D based digital to analog converters. Themajor advantage being that it is based predominantly on digital signal processing,hence the cost of implementation is low and will continue to decrease. Also, due to itsdigital nature S-D converters can be integrated onto other digital devices.Manufacturing technology notwithstanding, S-D technology offers system costsavings because the analog filter requirements are considerably less complexion. S-Dconverters are inherently linear and don't suffer from appreciable differentialnon-linearity, and the background noise level which sets the system S/N ratio isindependent of the input signal level. The last, but certainly not least, consideration iscost. Attaining a high level of performance at a fraction of the cost of hybrid andmodular designs is probably the greatest advantage of all. SDM is good, but notperfect.In this paper, a complete analog front end for low frequency measurementapplications is presented. The part can accept a serial digital word directly from atransducer and outputs analog signals. It employs a sigma-delta conversion techniqueto realize up to 90dB SNR. The basic specification and general measurement arediscussed. The mechanism of oversampling converters with Sigma-delta modulator isdiscussed. Systematic design is carried out and presents the specific parameterindexes according to the characteristics, basic functions and the related requirementsof the chip. Then goes on with the design and realization of the ananlog circuits.CMOS opamp and Switched-Capacitor filters is discussed, In the end, the layoutdesign is shown.