Characterisation of the new tracker sensors for the CMS experiment at CERN

I-V and C-V curves are crucial measurements required to characterise Silicon sensors. They must be performed at reception and at several steps of particle detector module assembly to spot potential damages. High-voltage (1kV) biasing of those sensors and accurate current measurements (50µA max) are mandatory for sensor characterization. High-voltage electrometers and LCR meters with proper decoupling are the typical instruments used to perform those measurements. Those instruments are rather expensive (10k euros range) and are often over-specified for this precise task. We developed a system tailored to perform both I-V and C-V measurements of sensors in one compact, low-cost instrument. The instrument is built around a PCB that implements a low ripple (100mV) 1kV highvoltage power supply, a high-side AC/DC current measurement circuit and a capacitance measurement circuit. The instrument is coupled to an external signal generator, a computer that extracts electrical parameters and the I-V/C-V curves, and a Programmable System-On-Chip (PSOC) which handles source control in addition to current, voltage and voltage/current phase measurements. On top of that, temperature and relative humidity are monitored. Finally, low-voltage DC regulators can power readout electronics of fully assembled modules to provide a standalone test station usable in sensor/module characterisation or in thermal cycling.