Differential Capacitive Bias Stability under Non-Uniform Substrate Thermal Fields
Spatial thermal gradients disrupt differential capacitive balance, requiring symmetric substrate layout and strain isolation to preserve bias stability.
Carrier Demodulation Phase Shift
Signal Alignment
Synchronous detection systems rely on precise timing agreements between the incoming modulated waveform and the local reference oscillator. Any deviation in this alignment introduces a carrier demodulation phase shift that attenuates the amplitude of the recovered sensor signal. The alignment mismatch can cause significant measurement crosstalk in dual-channel systems.
Distortion Consequence
When the reference clock does not align with the incoming carrier signal, the demodulated output decreases by the cosine of the phase error. This signal reduction degrades the signal to noise ratio and limits the resolution of the sensor. In severe cases, a carrier demodulation phase shift can invert the polarity of the output signal or produce non-linear distortion.
These effects introduce systematic offsets that escape standard amplitude-based calibration routines.
Propagation Delay
Electrical cables and input filtering stages introduce physical signal propagation times that vary with operating frequency. If the cable length changes or the temperature of the filter components drifts, the transmission delay shifts dynamically. This variance translates directly into a timing discrepancy at the demodulator.
Compensation Method
Automatic phase-tracking loops and software-controlled phase delay blocks adjust the reference signal to match the phase of the carrier. High-precision instruments utilize test signals to measure and null the phase mismatch before executing the main measurement cycle. This validation process keeps the residual phase error below one degree across the operational bandwidth.