DUT Supply Voltage Circuit With Capacitor-Suppressed Range Switching
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Solution Overview
Problem
Conventional methods for providing a supply voltage to a device under test often result in glitches due to rapid changes in resistance, which can damage the device and are difficult to fully control, especially when switching between different current measurement ranges.
Innovation Solution
An apparatus comprising a controlled source, a switchable resistor with different resistances, and a capacitor in parallel to the resistor, which slows down voltage changes across the resistor during switching, allowing the regulator to maintain a stable voltage at the device under test by injecting a compensation signal into the control loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switchable resistor is used to change current measurement ranges, then measurement versatility is improved, but voltage glitches are generated at the device under test port
Solution Approach 1:
The capacitor is pre-charged to the voltage present across the switchable resistor before switching occurs. When the resistor value changes, the capacitor's pre-stored voltage prevents a sudden voltage change at the output, thereby preventing glitches while allowing range switching
Solution Approach 2:
The capacitor acts as an intermediary element between the switchable resistor and the device under test. It mediates the voltage transition by providing a stored charge that smooths out the voltage change when the resistor value switches, preventing direct coupling of the glitch to the output
2Stability of the object's composition
If switches are operated slowly to avoid glitches, then voltage stability is improved, but switching speed and response time deteriorate
Solution Approach 1:
The capacitor is pre-charged to the appropriate voltage before the switch transitions. This preliminary charging action allows the switch to change state rapidly without causing voltage instability, as the capacitor compensates for the sudden resistance change instantaneously rather than requiring slow switching
3Measurement precision
If the control loop operates faster than the glitch to compensate, then voltage regulation accuracy is improved, but complete cancellation becomes difficult due to limited control over switch resistance
Solution Approach 1:
The capacitor serves as a passive intermediary that automatically compensates for resistance changes without requiring active control. This eliminates the need for complex fast control loops while maintaining voltage regulation accuracy, as the capacitor's natural charge-discharge behavior provides the necessary compensation
4Ease of operation
If switches are built to work slowly with gradual resistance change, then ease of control is improved, but the ability to follow fast voltage changes deteriorates
Solution Approach 1:
The capacitor is pre-charged to match the voltage across the switchable resistor before switching. This preliminary action allows simple, easily controlled switches to be used while still achieving fast voltage change response, as the capacitor's pre-stored energy enables instantaneous voltage maintenance during the transition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively prevents voltage glitches at the device under test, maintaining the voltage within ±5% of the desired value during resistance state changes, enabling continuous power supply and accurate measurements without the need for an auxiliary power source.
Implementation Method 1
a capacitor circuited in parallel to the switchable resistor at least during switching of the switchable resistor and configured to slow a voltage change across the switchable resistor which is caused by changing a switch state of the switchable resistor
Data Source
AI summary
An apparatus for providing a supply voltage to a device under test includes a controlled source configured to provide a voltage in dependence on one or more control signals; a switchable resistor circuited between the output of the controlled source and a DUT port, having first and second resistances in first and second switch states, respectively, the second resistance being smaller than the first resistance; a regulator configured to provide a control signal to the controlled source, to regulate a voltage to be provided to the DUT in dependence on information about a desired voltage; a capacitor circuited in parallel to the switchable resistor at least during switching of the switchable resistor and configured to slow a voltage change across the switchable resistor which is caused by changing a switch state of the switchable resistor; the apparatus being configured to change a switch state of the switchable resistor while a voltage is provided to the DUT via the switchable resistor.