Quick answer: In RF validation, lead resistance can create a difference between the programmed voltage and the DUT supply rail. Measure the DUT voltage during the real load waveform; use documented remote-sense capability where cable-drop compensation is needed.
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What lead resistance changes
With local sensing, the supply regulates near its output terminals. Current through both force leads and their connections creates a load-side drop. Measure total loop resistance or compare source and DUT voltages under load rather than assigning a cable resistance from its gauge alone.
Illustrative 60A calculation
Example assumptions: load current 60A, total force-loop resistance 5mΩ and a 3.30V terminal setpoint. The calculated drop is 60A × 0.005Ω = 0.30V, leaving 3.00V at the DUT. The drop is about 9.1% of 3.30V. These numbers are an engineering illustration, not a customer measurement.
If a compatible remote-sense loop regulates 3.30V at the DUT under the same steady-state conditions, the supply terminals would need about 3.60V. This requires sufficient voltage headroom and allowed compensation range. Cable heating remains I²R = 60² × 0.005 = 18W in this example; feedback compensation does not remove that loss.
What Remote SENSE can and cannot do
Separate high-impedance sense leads provide load-side voltage feedback while the force leads carry output current. Feedback can reduce steady-state cable-drop error within the specified compensation range. Final accuracy still depends on the supply, connections and measurement method. Dynamic rail behaviour also depends on bandwidth, cable inductance, load changes and permitted local decoupling.
Apply the check to mmWave and phased-array tests
Use the actual module documentation for rail voltage, current waveform and allowed ripple. A large array, board or transceiver may have several rails with different requirements; do not assign a universal 3.3V/60A requirement to all mmWave devices. Monitor the DUT rail during transmit bursts and other relevant operating states.
Remote SENSE is one part of the fixture
Compensation alone cannot guarantee EVM, phase noise or reset-free operation. Force-lead inductance, decoupling permitted by the module, supply settling and the RF measurement setup also matter. Validate the intended waveform and assess RF results from measurements.
Evidence for a useful application report
- Exact DUT and supply configuration, including interfaces and SENSE options.
- Rail tolerance, representative current waveform and fixture wiring.
- DUT-side voltage and RF results before and after the documented change.
- Clear separation of calculations, measured results and customer-approved statements.
Evaluate the eTM-30200C configuration
The eTM-30200C product data lists 0–30V, 0–200A and 6000W. For a SENSE-equipped test setup, confirm the ordered option, compensation limits, supported communication and wiring instructions. A voltage/current rating alone does not verify transient recovery, sub-millivolt accuracy or open-sense protection.
Practical checks
| Check | What to verify |
|---|---|
| Rail requirements | Use the module’s actual voltage tolerance and current waveform. |
| Cable drop | Measure total force-loop and contact resistance. |
| Dynamics | Check DUT voltage during transmit bursts, not only at idle. |
| Compensation | Validate SENSE range, wiring and stability with the exact instrument. |
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