Noise Floor Reduction in Frequency Delta-Sigma Modulation Microphone Sensors

Delta-Sigma Modulation in Fractional-N Frequency Synthesis

This paper describes a delta-sigma ( A-Z ) modulation and fractional-S frequency division technique to perform indirect digital frequency synthesis based on the use of a phaselocked loop (PLL). The use of 1 Y modulation concepts results in a beneficial noise shaping of the phase noise (jitter) introduced by fractional-S division. The technique has the potential to provide low phase noise, fast ...

Hexagonal Sigma–Delta Modulation

A novel application and generalization of sigma–delta ( ) modulation has emerged in three-phase power-electronic converters. A conventional modulator with scalar signals and binary quantizer is generalized to a modulator with vector signals and a hexagonal quantizer. Indeed, power-electronic switching states may be thought of as determining the quantizer outputs. The output spectrum is a key pe...

Dual Microphone Noise Reduction Algorithms

Noise Shaping in Sigma-Delta Modulator

A new noise-shaping coding scheme is derived by using an autoregressive moving average model and by bounding and minimizing its reconstruction error. The stability of the system and performance can be analysed easily. All-zero first order and second order shaping filters are used to study the effect of the proposed scheme on the perceptual quality of speech signals.

Delta-sigma modulation in single neurons

In this paper we investigate the relationship between the pulse-coded signal representation found in biological neurons and signals represented by first-order delta-sigma bit-streams. We show that a first-order delta-sigma bit-stream is a digital equivalent to a pulse-coded neural signal. By increasing the clock frequency, a delta-sigma bit-stream can approach a pulse-coded representation with ...