Blue-Noise Sigma-Delta Modulator: Improving Substrate Noise and Nonlinear Amplifier Gain Effects

This paper presents a method to reduce the effects of substrate noise and nonlinear amplifier gain on sigma-delta (SigmaDelta) modulators through the use of blue-noise modulation. In addition to reducing the effects of substrate noise and nonlinear amplifier gain, the proposed architecture also suppresses the effects of integrator opamp non-idealities, such as 1/f noise and DC offset, and DAC DC offset and even-order nonlinearities. The architecture proposed herein is referred to as the blue-noise SigmaDelta modulator. An example utilizing a third-order blue-noise SigmaDelta modulator with a 1-bit quantizer is presented. Additionally, a method to generate the required blue-noise modulation sequence is proposed. Simulation results demonstrate that this architecture achieves an 8.8dB improvement in SNDR over the traditional third-order SigmaDelta modulator.