High-order cascade multi-bit Σ∆ modulators for high-speed A/D conversion

Abstract

The use of Sigma-Delta (Σ∆) modulation for analog-to-digital conversion (ADC) in the communication frequency range is evaluated. Two high-order multi-bit architectures are proposed to achieve +12-bit dynamic range at 4Msample/s Nyquist rate using very low oversampling ratio. They show very low sensitivity to the internal D-to-A conversion (DAC) error with no calibration required. Simulations show that such performance can be achieved even in presence of circuit imperfections