Meaning
Analog-to-digital converters utilizing oversampling and noise shaping achieve high-resolution digitization of low-frequency analog signals. The delta-sigma adc is particularly suited for precision measurement applications like oceanographic temperature sensing where speed is less critical than resolution. Its operation is limited to relatively low input bandwidths due to the high oversampling ratios required.
Signal Processing
The converter samples the analog input at a frequency much higher than the Nyquist rate to spread the quantization noise across a wide spectrum. This oversampled signal passes through a feedback loop that integrates the difference between the input and a reconstructed analog value. A digital decimation filter then processes the high-speed bitstream to produce a high-resolution output at a lower rate.
The resulting data stream is highly immune to high-frequency environmental noise.
Noise Reduction
Shifting the quantization noise to higher frequencies where it can be easily filtered out is a primary mechanism of this architecture. This noise shaping capability allows the converter to achieve effective resolutions exceeding twenty bits without requiring highly matched analog components. The absence of complex analog circuitry simplifies the physical layout on the silicon die.
Sensor Integration
Oceanographic data loggers rely on these converters to resolve sub-millikelvin changes from temperature probes. This direct digitization simplifies the front-end electronics and improves long-term calibration stability.
