Board Layout Mitigation Strategies for Thermally Coupled Internal Reference Voltage Drift
Isothermal component placement, substrate trenching, and balanced copper pours mitigate internal reference voltage drift caused by thermal board stress.
High Resolution ADC ENOB Degradation
Signal Quality
Analog-to-digital converter performance decreases when internal noise sources or clock jitter affect the digitizing process. This reduction in performance is described as high resolution ADC ENOB degradation, which measures the loss of effective number of bits relative to the ideal converter specifications. The calculation holds valid only within the specified input frequency band and sample rate.
Thermal Noise
High-resolution converters are sensitive to thermal noise generated by internal resistors and active silicon elements. As the operating temperature rises, the thermal noise floor increases, which directly compromises the signal-to-noise ratio. This noise increase reduces the voltage resolution of the converter, making it difficult to resolve low-level signals.
The relationship between temperature and noise floor governs the limits of the converter.
Harmonic Distortion
Nonlinearities within the sample-and-hold circuit introduce harmonic distortion components into the digital output. These unwanted signals increase the total harmonic distortion, which further reduces the effective number of bits. Clock jitter also contributes by causing timing uncertainties that elevate the noise floor when digitizing high-frequency signals.
Converter Qualification
Calibration labs assess these performance losses by applying a pure, low-noise sine wave and analyzing the fast Fourier transform of the digitized output. This test yields the signal-to-noise-and-distortion ratio, which is converted mathematically into the effective number of bits. When the measured effective bits fall below the system threshold, the system must undergo design optimization or thermal management.
This qualification process confirms the suitability of the converter for precise scientific measurements.