Tune a transistor sweep with an MFLI

This example sweeps one Basel DAC channel across a transistor gate and records the MFLI amplitude and phase. It includes both stepped and buffered versions so you can compare a known-good slow measurement with the hardware-timed result.

Start from the sweep timing

The demodulator must produce enough samples during each DAC step. The example sets the lock-in frequency and sample rate from the shortest point delay it plans to use:

min_delay = 0.03e-3

lockin.frequency(2 / min_delay)
sample_rate(2 / min_delay)

Treat this as a starting point, not a universal setting. A rate that is too low can smear or drop points; a rate that is unnecessarily high can also make the DAQ fetch unreliable. Confirm the returned data while tuning it.

Tune the acquisition

The buffered function exposes the settings most likely to need adjustment:

  • trigger_delay aligns the MFLI sample window with the updated gate voltage.

  • tc_factor controls how much settling time is allowed relative to the demodulator time constant.

  • grid_mode="linear" lets the DAQ module place samples on a uniform grid.

Use the stepped sweep as a reference, then compare it with buffered runs over a small range of trigger delays and time-constant factors. This is more reliable than carrying timing values over from a different device or wiring setup.

Full example: buffered_basel_transistor_test_mfli.py