Internal Bandgap Voltage Error Reduction in High Gradient Layouts
Internal bandgap voltage errors in high gradient layouts are reduced by common-centroid matching, thermal isolation trenching, and package stress mitigation.
Dynamic Element Matching
Randomization Technique
Digital algorithm patterns dynamically rotate the usage of mismatched physical components to convert systematic errors into high-frequency noise. Using dynamic element matching averages out the device variations over time, which improves the dynamic range of multi-bit delta-sigma converters.
Quantization Noise
The mismatches among resistors or current sources in a digital-to-analog converter create harmonic distortion. Dynamic rotation scatters these discrete error tones across a wide frequency band, effectively shaping the noise away from the signal of interest. This high-frequency noise is then easily removed by a subsequent low-pass filter.
Switching Speed
Implementing the rotation logic introduces additional gate delays and increased power consumption. The clock frequency must be high enough to allow multiple rotations within a single conversion cycle, which places a limit on the maximum input signal bandwidth. In high-speed designs, the dynamic switching transient itself can introduce asymmetrical errors if the rise and fall times are not matched.
Linearity Performance
Precision converters are characterized by measuring their integral and differential non-linearity across the entire code range. Long-term testing shows that the randomized errors remain stable even as the individual components drift with age and temperature. The method achieves high linearity without requiring factory trimming.