Calculating Group Delay in Delta Sigma Converters
Delta-sigma converter group delay equals the phase derivative across decimation filter stages, calculated as K times M minus one divided by twice the modulator clock for sinc filters.
Sample Rate Downsampling
Data Reduction
Process of decreasing the temporal resolution of a discrete signal by removing samples at regular intervals. Sample rate downsampling reduces the volume of data that must be processed or stored by downstream systems. It is typically preceded by a low pass filter to prevent high frequency components from aliasing into the new, lower Nyquist band.
Aliasing Prevention
Filtering stages must attenuate all energy above the new folding frequency to maintain signal integrity. During sample rate downsampling, the decimation factor determines the integer ratio of the input rate to the output rate. If the anti aliasing filter is insufficient, the resulting data will contain artifacts that cannot be removed by subsequent processing.
Spectral Verification
Spectral analysis of the output confirms that no aliasing has occurred. Engineers use these measurements to validate that the sample rate downsampling process has not introduced unwanted noise into the signal.
Resource Management
Implementation in hardware requires careful management of buffer sizes and memory bandwidth. Sample rate downsampling is used to match the output of a high speed sensor to the processing capabilities of a lower speed controller. The precision of the resulting data is limited by the quality of the decimation filter and the bit depth of the arithmetic units used in the calculation.