Key Features PXI Express Peripheral Module (X1 PCI Express Link) Four quadrant operation 18-bit source/measure resolution (multiple selectable ranges) Low output noise High measurement speed (100k s/S) High output slew rate Optional measurement log DIO/Trigger bits Output profiling by hardware sequencer Programmable output resistance Floating & Guarding output 16 Control Bandwidth Selection Master / Slave operation Driver with LabView/LabWindows & C/C# API Softpanel GUI Model 52400e Series SMU Model 52400 Series SMU

APPLICATIONS

OVERVIEW

The Chroma 52400e series is a PXIe based SMU (Source Measurement Unit) card designed for highly accurate source or load simulation with precision voltage and current measurements.

The SMU combines four-quadrant operation with precision and high speed measurement. This makes the SMU an ideal instrument in many parametric test applications ranging from ICs, two-leaded components such as sensors, LEDs, laser diodes, transistors, to solar cells, batteries and many other electronic devices.

The 52400e series features: 16 selectable control bandwidths to ensure high speed output and stable operation; multiple source/measure ranges with an 18-bit DAC/ADC to provide the best resolution and accuracy available with a sampling rate up to 100K s/S; programmable internal series resistance for battery simulation; ±force, ±sense and ±guards lines to avoid leakage current and reduce settling time -- especially useful for low current test applications.

The 52400e series has a patented hardware sequence engine that uses deterministic timing to control each SMU. The sequencer's on-board memory can store up to 65535 sequencer commands and 32k measurement samples per channel, allowing cross module/ card synchronization and latency free output control and measurement. No PC communication is required during execution of the hardware sequencer test process.

C, C#, LabView, LabWindows APIs and versatile soft front panels come standard with each SMU. The back connectors are compatible with both PXIe and hybrid chassis. All of these features enable easy integration to PXIe or PXI-hybrid systems designed for a wide range of applications.

FOUR QUADRANT OPERATION

All Chroma 52400e series SMUs support four quadrant operation for applications that require a reverse voltage/current source or load. During a load operation, the module is limited by the PXI chassis' standard of 20W heat dissipation per slot. Shown below are the quadrant diagrams with the operating regions of the Chroma PXIe SMUs:

CONTROL BANDWIDTH SELECTION

To reduce test times, Chroma's SMUs are designed for fast response providing high speed output voltage and current. The impedance of the DUT, fixture, or cabling may cause loop instability under voltage or current source mode. An unstable loop can cause saturation, oscillation, or even damage the DUT.

To prevent system instability, the 52400e series SMUs provide 16 user selectable control bandwidths, eliminating the need for external capacitors or inductors placed near the DUT. This results in faster output rise time, reduced voltage ripple and noise, and reduced transient response. The control bandwidth can be modified via software to maximize test flexibility and minimize downtime when changing DUTs.

UNIQUE HARDWARE SEQUENCER

The Chroma Hardware Sequencer is a powerful tool that can predefine commands as instrument executable steps. This allows latency free control and measurement since no PC interaction is required during execution. Once the instrument receives the start trigger, it will execute step commands in the sequencer table line by line or as defined by the trigger. Shown below are the soft panels for the SMU in hardware sequencer mode (left) and direct operation mode (right).

GUARDING FOR LOW CURRENT APPLICATION

Guarding is an important technique for very-low current measurements. Guarding reduces leakage current error and decreases settling time. This is achieved by keeping the potential of the guard connector at the same potential as the force conductor, so current does not flow between the force and guard conductors. Guarding also eliminates the cable capacitance between the SMU and DUT.

The Chroma 52400e series features two ±guard wires per channel, resulting in faster and more accurate measurements.

MASTER/SLAVE OPERATION

For maximum flexibility, the Chroma 52405e SMUs support Master/Slave operation when higher current under FVMI (Force Voltage Measure Current) mode is required. To ensure accurate current sharing between modules and maximum performance, Master/Slave operation is only allowed between SMUs of the same model number.
Current sharing is achieved by one channel operating as the Master under FVMI mode while the Slaves operate in FIMV mode. The Master channel is programmed in voltage mode while the Slaves are set to current mode. The Slaves will follow the Master's set voltage. The wiring diagram for current sharing in master/slave control is shown to the right.

		Using a Source Measure Unit as a Device Power Supply for Semiconductor Testing This document is going to explain why Source Measure Unit (SMU) is an ideal Device Power Supply (DPS) for semiconductors testing. SMUs are optimized for both speed and precision, repeatability, and they offer faster rise time and much lower measurement uncertainty than typical power supplies. Due to the combination of source and measurement into a single unit, many advantages are found during semiconductor testing. The high level of integration and remarkable flexibility make the SMUs ideal and economical for semiconductor testing. Download
		Optimal SMU Response by Large Selectable Control Bandwidths for Capacitive Loads Typically, SMUs are considered the user’s DUT as part of the control loop. It is difficult for the designer to guess what exact load a user will need to measure. Some capacitive loads can cause ringing in the transient response of the device and make the system unstable. The “Optimized Control Bandwidth” offers much better settling times with no overshoot. It therefore provides the SMU output an optimized response. Chroma SMUs provide 16-step programmable slew rate. Users can select the control loop for optimal SMU responses to electrical loads and obtain an ideal response with minimum rise times and without overshoot or oscillations. Download
		Guarding : Guard Shield Used For Low Current (nano-Amp) Measurement Guarding - A technique that reduces leakage current errors and decreases response time. It keeps the potential of the guard connector at the same potential as the force conductor, so current does not flow between the force and guard conductors. It also eliminates the cable capacitance between source measure unit (SMU) and DUT for faster and accurate measurements.  A guard is a low-impedance point in the circuit that’s at the same potential as the high-impedance lead in the circuit. In a guarded measurement, because the shield is driven to the same potential as the force high terminal of the SMU (Source Measure Unit), no current flows through the insulation medium; therefore, eliminates leakage current effects. Download
		Guarding: Enhance DC Transmission Speed for Very Low-current Measurement Guarding - A technique that reduces leakage current error and decreases settling time. It keeps the potential of the guard connector at the same potential as the force conductor, so current does not flow between the force and guard conductors. It also eliminates the cable capacitance between source measure unit (SMU) and DUT for faster and accurate measurements. This document describes how to reduce settling time for very-low current measurement.    Download