## What is a Sigma Delta conversion?

A fairly new commercial converter is the sigma-delta ADC (sometimes referred to as a delta-sigma converter). This device is a low-cost, high-resolution ADC, suitable for low conversion rates. Sigma-delta ADCs typically have 16 to 24-bit resolution, with a usable input signal frequency range of a few Hz to a few kHz.

Decimation is a method of observing only a periodic portion of the ADC samples, while ignoring the rest. The result is to reduce the sample rate of the ADC. For example, a decimate-by-4 mode would mean (total samples)/4, while all other samples are effectively discarded.

What does a sigma delta modulator do?

Motivation. Delta-sigma modulation converts an analog voltage signal into a pulse frequency, or pulse density, which can be understood as pulse-density modulation (PDM).

### What is delta modulation in ADC?

A delta modulation (DM or Δ-modulation) is an analog-to-digital and digital-to-analog signal conversion technique used for transmission of voice information where quality is not of primary importance.

Why is decimation needed?

Decimation is useful in applications in which the Nyquist frequency of a signal is much higher than the highest frequency of the signal. Decimation filters help you remove the excess bandwidth and reduce the sampling frequency of the signal.

What is the difference between decimation and downsampling?

Loosely speaking, “decimation” is the process of reducing the sampling rate. In practice, this usually implies lowpass-filtering a signal, then throwing away some of its samples. “Downsampling” is a more specific term which refers to just the process of throwing away samples, without the lowpass filtering operation.

#### What happens in delta modulation?

In delta modulation, the transmitted data are reduced to a 1-bit data stream. Its main features are: The analog signal is approximated with a series of segments. Each segment of the approximated signal is compared to the preceding bits and the successive bits are determined by this comparison.

Why do we use delta modulation?

Delta Modulation is most useful in systems where timely data delivery at the receiver is more important than the data quality. This modulation is applied to ECG waveform for database reduction and real-time signal processing. For analog-to-PCM encoding, this Modulation method is used.