PXIe-4163 Theory of Operation

The PXIe-4163 combines a digital control loop architecture, known as SourceAdapt, with precision electronics to implement constant voltage (CV) or constant current (CC) sources with built-in measurement of voltage and current output.

One significant advantage of SourceAdapt is the ability to make precise adjustments to the control loop to customize the SMU transient response to any load, so you can achieve an ideal transient response with minimum rise times and no overshoots or oscillations.

The PXIe-4163 can operate in either CV mode or CC mode:

• In CV mode, the device acts as a precision voltage source that holds the voltage across the selected voltage sense points constant with respect to load changes as long as load current is below the programmed current limit.
• In CC mode, the device acts as a precision current source that holds the current across the load constant with respect to load changes as long as load voltage is below the programmed voltage limit.

The PXIe-4163 features a measurement circuit that simultaneously reads the voltage and current values using two integrating analog-to-digital converters. The circuit measures the voltage values differentially between the HI and LO terminals (local sense) or between the HI Sense and LO Sense terminals (remote sense) based on the programmed voltage sense location. It uses remote sense to compensate for voltage drop that results from resistance in cables, connectors and switches. The circuit measures the current values using shunt resistors in series with the HI terminal.

The PXIe-4163 has several built-in protection mechanisms that guard against common faults. The output has an over-current protection (OCP) circuit that opens the Output Disconnect switch when an over-current condition is either too severe or lasts too long.

The PXIe-4163 continuously monitors voltage on the Output HI, Input HI Sense and Input LO Sense terminals and protects against over-voltage faults. If an excessive voltage is detected, the over-voltage protection (OVP) circuit opens the Output Disconnect switch to protect the device from excessive over-voltage.

The output terminals of the PXIe-4163 are electrically isolated from chassis ground through a 60 VDC, functional isolation barrier. This allows any SMU terminal to float ± 60 VDC with respect to chassis ground. However, there is no isolation between channels because the LO terminals of each channel are internally connected.

The PXIe-4163 includes flexible source and measurement units that enable multiple programming modes and timing options:

Single Point Source Mode—Use for software-timed source or measurement operation.

Sequence Source Mode—Use for basic hardware-timed operation where you specify a set of setpoint steps and source delays between each step while other parameters are held constant.

Advanced Sequencing Mode—Use for hardware-timed operation where full control of all supported parameters are available for each step.

You can use hardware triggers in all the above modes to control operation of the source and measure units with other channels or devices in the system. The measurement engine operation can operate in waveform acquisition mode and can be decoupled from the sequence engine.