Digital Subsystem
One fundamental tenet for most functional test applications is to validate performance of the device under test without harming or degrading its capabilities, and the digital subsystem is ideal for this type of verification. <Read More> Prior to applying power to the DUT, test system continuity is verified by detecting the electrostatic discharge (ESD) protection diodes found on the device pins using the PMU force current / measure voltage mode.
The parametric measurement unit (PMU) capabilities found on most high-end dynamic digital instruments is ideal for these applications and MTS’ GX5295 32-channel dynamic digital instrument provides per-pin PMU functionality, as well as programmable logic levels. A current is sourced and the resulting voltage drop across the ESD diode is measured. This should be consistent with the voltage drop across a typical semiconductor junction. An issue with the test system connection, or a defective device under test, will result in an open circuit or a voltage inconsistent with the expected junction voltage drop.
The digital subsystem is also used for communications with, and control of, the device under test. Multiple serial bus emulation protocols are supported including SPI and I2C; custom protocols are also supported and easily implemented. Additional system level functionality, such as test fixture identification, is also supported.
Power Subsystem
Stable, precise programmable DUT power is crucial in mmWave semiconductor device test, whether in the laboratory or on the production floor, with production test system throughput requirements placing additional demands on the power subsystem as multiple devices must now be powered and tested in parallel. A multi-channel source measure unit (SMU) proved to be the ideal solution to meet these challenges.
Precise power is delivered to the DUT utilizing the SMU’s Kelvin connections to negate the effects of cabling and associated interconnect voltage drops. Current draw is precisely measured while stepping the DUT through its various operation states, both to characterize the device in the laboratory and to verify performance when in the production test environment.
The GX3104, 4-Channel SMU delivers stable, accurate DUT power in a multi-channel configuration that is ideal for these applications. Multiple SMUs can be used to provide sufficient DUT power to dual-site and quad-site applications and the scalable nature of the power source also simplifies future expansion in line with the MOSA design philosophy to support a much higher DPS channel count.