|Dimensions||1000μm x 1170μm|
In this diploma thesis an integrated Sigma Delta modulator for a high-quality DVD audio A/D converter has been designed and implemented in a 0.18um CMOS technology.
This modulator has been implemented as a switched-capacitor circuit consisting of a single loop with a 5th-order filter and a tri-level quantizer.
With respect to performance the most critical part of this modulator is the input stage which includes the first integrator and the D/A converter. Analysis of an input stage based on a common non-inverting integrator has shown that the required resolution of 18bits cannot be achieved with the available circuit elements due to DAC nonlinearity and flicker noise. An improved input stage based on correlated double sampling has been analyzed with regard to circuit noise and DAC linearity. Numerical simulations based on symbolic calculations have confirmed that the required resolution can be achieved with this improved input stage even with worst-case capacitor mismatch and amplifier offset. The capacitors are sized in order to obtain a SNR of 110dB, corresponding to 18bit resolution. The signal bandwidth is 24kHz and the die size is 1.17mm2