DRS4 Evaluation Board User’s Manual
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1. Introduction
The DRS4 chip, which has been designed at the Paul Scherrer Institute, Switzerland by Stefan
Ritt and Roberto Dinapoli is a Switched Capacitor Array (SCA) capable of digitizing eight
channels at sampling speeds up to 5 GSPS. This chip is available through the PSI technology
transfer program for other institutes and organizations. In order to simplify the design process
to integrate the DRS4 chip into custom electronics, an evaluation board has been designed,
which demonstrates the basic operation of the chip. It has SMA connectors for four input
channels CH1 to CH4, an USB 2.0 connector and MMCX connectors for triggering and clock
synchronization (Figure 1). The board is powered through the USB port and contains an on-
board trigger logic. It comes with MS Windows®and Linux drivers and two application
programs. It is basically equivalent to a four channel 5 GSPS digital oscilloscope.
This manual describes the software installation, the usage of the application programs, and
gives hints for developers seeking to build new electronics around the DRS4 chip.
1.1. Board description
Since the DRS4 chip has differential inputs, the board uses four active buffers (THS4508
from Texas Instruments ®) to convert the 50-Ohm terminated single ended inputs into
differential signals. Analog switches in front of the buffers (ADG901 form Analog Devices®)
are used to de-couple the inputs during calibration. Two reference voltages are generated by
the on-board 16-bit DAC to measure the offset and gain of all DRS4 storage cells for
calibration. The four analog inputs are AC coupled and have a input range of 1 V peak-to-
peak. The absolute maximum input voltage range is -0.5V to +2.8V. The DRS4 is read out
with a 14-bit ADC (AD9245 from Analog Devices®) and a FPGA (Xilinx®Spartan 3). The
USB connection is implemented with a micro controller (Cypress®CY2C68013A). The high
speed modus of the USB 2.0 bus allows for data transfer rates of more than 20 MB/sec.
Figure 1: Picture of the DRS4 Evaluation Board V4 with different components
