Multi Coil Quadrature Demodulation Signal Chains for Proximity Measurement
Multi coil quadrature demodulation isolates amplitude and phase in inductive proximity chains, resolving sub-micron targets while rejecting thermal noise.
Inter-Channel Phase Skew
Timing Discrepancy
A temporal offset between two or more digitized signals occurs when parallel acquisition channels do not sample simultaneously. This delay, known as inter-channel phase skew, introduces critical errors in multi-axis measurements and phase-sensitive demodulation systems. When high-frequency waves are processed, even a picosecond offset alters the calculated phase relationships between currents and voltages.
It degrades the accuracy of power analyzers and ultrasound arrays.
Signal Integrity
Digital signal processors rely on synchronous inputs to compute vector parameters and spatial orientation. When the phase skew exceeds the allowable limit, the calculated coordinates of a target or the power factor of a load shift from their true values. This error distorts the measurements of high-speed data acquisition boards.
In phase-coherent systems, this skew can render the entire measurement invalid.
Propagation Delay
Differences in trace lengths on printed circuit boards and variations in the internal delays of analog-to-digital converters are the primary physical causes of the skew. A one-millimeter difference in trace length on standard FR4 substrates introduces approximately six picoseconds of delay. Semiconductor manufacturing tolerances also create minor channel-to-channel variations in aperture delay.
Mitigation Technique
Dynamic compensation algorithms align the digitized streams by applying fractional-delay filters. Hardware calibration using a shared clock minimizes the skew before digitization. This step is verified by feeding a single reference sine wave into all channels simultaneously.