| Analog to Digital converter(ADC)can transfer analog signals to digital signals,which isan important bridge for information transmission.With the development of integrated circuits,higher resolution has become one of the requirements for the use of ADC in digital circuits.Compared with conventional Nyquist ADC,Sigma Delta ADC can obtain much higher resolution and signal to noise ratio(SNR).Sigma Delta ADC takes advantage of oversampling and noise quantization technology.The complexity of Sigma Delta ADC is much lower.As a consequence,it can be integrated in ASIC of digital signal process.Sigma Delta ADC has been the best candidate for analog to digital conversion.In this context,the principle of the Sigma Delta converter modulator is firstly introduced.Then this paper analyzes and compares the different architectures of modulator.The 1 bit second order modulator is chosen as the modulator structure of Sigma Delta ADC.The modulator is modeled by MATLAB,and the circuit is then designed.The circuits of Modulator are realized with switched capacitor,which contains quantizer,bandgap voltage reference,operational amplifier and switched capacitor integrator and so on.Simulation is carried out with Candence AMS,and then the result shows that the performance meets requirement very well.The Bandwidth of Signal the ADC designed is 400 k Hz,Oversampling Rate of it is 128.For Sigma Delta ADC,the Frequency of Oversampling is 102.4MHz,the Conversion Rate of it is 6.10 KSPs,Dynamic Rang of it is 96.32 d B and the SNR of it is 94 d B.The resolution of Sigma Delta converter presented can alternate within 2bit to 16 bit.In the end,the circuits of Sigma Delta ADC are implemented in SMIC 0.13?m technology.The circuit of Sigma Delta modulator adopts full custom design,and the area of layout is 112?m * 206?m.While the circuit of digital controller is synthesized with standard cell,and the area of layout is 150?m * 200?m.The gross area of Sigma Delta converter is0.06mm2. |
PDF Full Text Request