How does the digital filter work in a sigma-delta ADC?
In a sigma-delta ADC, the digital filter averages the 1-bit data stream, improves the ADC resolution, and removes quantization noise that is outside the band of interest. It determines the signal bandwidth, settling time, and stopband rejection. Figure 9. Digital side of sigma-delta modulator.
Why is RMS noise less in Sigma Delta converters?
The RMS noise is less, because most of the noise passes through the digital filter. This action enables sigma-delta converters to achieve wide dynamic range from a low-resolution ADC. Figure 2. FFT diagram of a multi-bit ADC with a sampling frequency kFS.
How is a delta-sigma converter used in a quantizer?
A delta-sigma converter uses many samples from the modulator to produce a stream of 1-bit codes. The delta-sigma ADC accomplishes this task by using an input-signal quantizer running at a high sample rate. Like all quantizers, the delta-sigma modulator takes an input and produces a stream of digital values that represents the voltage of the input.
What are the basic principles of the σ-delta ADC?
This high level block diagram and the key concepts of the Σ- ADC are shown in Figure 1. Figure 1. Pillar concepts of the Σ-Δ ADC. As the Σ- modulator is an oversampled architecture, let’s start with the sampling theory and the scenario of Nyquist and oversampled ADC operation.
What is the theory behind a delta delta ADC?
Abstract: This in-depth article covers the theory behind a Delta-Sigma analog-to-digital converter (ADC). It specifically focuses on the difficult to understand key digital concepts of over-sampling, noise shaping, and decimation filtering.
What is the signal to noise ratio for a multi-bit ADC?
Figure 1. FFT diagram of a multi-bit ADC with a sampling frequency FS. If we divide the fundamental amplitude by the RMS sum of all the frequencies representing noise, we obtain the signal to noise ratio (SNR). For an N-bit ADC, SNR = 6.02N + 1.76dB.