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Delta-sigma (ΔΣ; or sigma-delta, ΣΔ) modulation is an oversampling method for encoding signals into low bit depth digital signals at a very high sample-frequency as part of the process of delta-sigma analog-to-digital converters (ADCs) and digital-to-analog converters (DACs).
To achieve high signal-to-noise ratio, delta modulation must use oversampling techniques, that is, the analog signal is sampled at a rate several times higher than the Nyquist rate. Derived forms of delta modulation are continuously variable slope delta modulation, delta-sigma modulation, and differential modulation.
Pulse-width modulation (PWM), also known as pulse-duration modulation (PDM) or pulse-length modulation (PLM), [1] is any method of representing a signal as a rectangular wave with a varying duty cycle (and for some methods also a varying period). PWM is useful for controlling the average power or amplitude delivered by an electrical signal.
A delta-sigma ADC (also known as a sigma-delta ADC) is based on a negative feedback loop with an analog filter and low resolution (often 1 bit) but high sampling rate ADC and DAC. The feedback loop continuously corrects accumulated quantization errors and performs noise shaping : quantization noise is reduced in the low frequencies of interest ...
Noise shaping is commonly implemented with delta-sigma modulation. Using delta-sigma modulation, Direct Stream Digital achieves a theoretical 120 dB SNR at audio frequencies using 1-bit audio with 64× oversampling.
English: Simple circuit performing delta-sigma modulation on an input 20 kHz sine wave s(t). An ideal op amp integrator using s(t) and p(t) produces ε(t), which can be quantized and sampled by an ideal D flip flop to produce a pulse density modulation result p(t), which used as negative feedback.
DAC use delay element with +. Move delta & sigma above the specific block. 21:27, 28 August 2023: 854 × 539 (128 KB) Em3rgent0rdr: removed "x" from summation circles, so won't be confused for multiplication: 06:47, 20 August 2023: 854 × 539 (128 KB) Em3rgent0rdr: used new integrator symbol, and named modulation DSM & "demodulation" out: 17:57 ...
From uniformly spaced samples it produces a function of frequency that is a periodic summation of the continuous Fourier transform of the original continuous function. In simpler terms, when you take the DTFT of regularly-spaced samples of a continuous signal, you get repeating (and possibly overlapping) copies of the signal's frequency ...