摘要
This paper introduces a new method for SC sigma-delta modulator modeling.It studies the integrator＇s different equivalent circuits in the integrating and sampling phases.This model uses the OP-AMP input pair＇s tail current（I_0） and overdrive voltage（v_（on）） as variables.The modulator＇s static and dynamic errors are analyzed.A group of optimized I0 and von for maximum SNR and power x area ratio can be obtained through this model.As examples, a MASH21 modulator for digital audio and a second order modulator for RFID baseband are implemented and tested, and they can achieve 91 dB and 72 dB respectively,which verifies the modeling and design criteria.
This paper introduces a new method for SC sigma-delta modulator modeling.It studies the integrator＇s different equivalent circuits in the integrating and sampling phases.This model uses the OP-AMP input pair＇s tail current（I_0） and overdrive voltage（v_（on）） as variables.The modulator＇s static and dynamic errors are analyzed.A group of optimized I0 and von for maximum SNR and power x area ratio can be obtained through this model.As examples, a MASH21 modulator for digital audio and a second order modulator for RFID baseband are implemented and tested, and they can achieve 91 dB and 72 dB respectively,which verifies the modeling and design criteria.
