Phase Margin Degradation from Digital Filter Latency in Control Loops
Digital filter latency introduces pure time delay into feedback loops, eroding phase margin at crossover frequencies by 360 degrees per cycle of propagation delay.
ADC Conversion Time
Signal Latency
Analog to digital conversion time designates the discrete interval required for a successive approximation register or sigma delta circuit to translate an incoming continuous voltage into a corresponding digital word. The internal clock cycles of the sampling peripheral govern this duration from the exact trigger edge until the data register latches the final bit. Designers specify the parameter across standard operating temperatures and supply voltages because thermal shifts and voltage droop alter internal comparator propagation delays.
Clock Constraint
Semiconductor manufacturers determine this temporal boundary by counting the necessary oscillation periods for settling the sample and hold capacitor and resolving each successive bit. Higher resolution architectures demand longer processing intervals because every added binary output requires another discrete comparison step within the conversion engine. External system designers balance sample rates against available processing windows to prevent aliasing errors during high frequency data acquisition.
Thermal Drift
Ambient temperature changes alter internal oscillator frequencies and introduce offset errors that stretch the duration required for valid bit decisions. Circuit engineers mitigate these environmental distortions by employing temperature compensated references and maintaining tight thermal management across the printed circuit board layout.
Aperture Jitter
Timing uncertainty between the sampling command and the actual initiation of the bit conversion process degrades signal reconstruction fidelity in high speed systems. Phase noise on the sampling clock injects sampling jitter that directly limits the effective number of bits at higher input frequencies. Careful clock distribution and low phase noise oscillator selection preserve measurement integrity throughout the conversion chain.