Speaker
Description
Summary
The Front-End R&D group at Fermilab has been developing front-end electronics to meet
the stringent requirements of high-energy physics (HEP) experiments. A peripheral
component interconnect (PCI) based test stand was developed at Fermilab to meet the
high-speed readout requirements of the electrical characterization of the silicon
strip and pixel modules used in HEP experiments. This test stand is developed around
a PCI test adapter (PTA). The PTA has a Xilinx Virtex4 field programmable gate array
(FPGA) that gives it the flexibility necessary to meet, for example, the changing
demands of the pixel module characterization (e.g., as new ICs are designed) and
different applications. The data bus from the pixel modules is connected to the
low-voltage differential signaling (LVDS) ports, and the data is packed by the FPGA
and stored in the local ZBT memory banks until further readout by the PCI bus. A
66MHz PCI-mastering device (PLX Technology PCI9056) maps the local ZBT memory banks
to the computer’s memory using direct memory access (DMA). The PTA has other
features such as a USB2.0 interface (useful for applications using a laptop computer)
and a pair of high-speed serializers - deserializers (SERDES) used to expand the data
traffic capabilities of the board. The PTA is distributed with drivers and middleware
that works in both Windows and Linux environments. Data acquisition and data analysis
software have been developed for both operational systems as well. Over 100 PTAs have
been produced, distributed, and being used in test stands around the world. One of
these applications is testing pixel modules using the third version of the Fermilab
pixel chip (FPIX2).
PTA Specifications
PCI: The PTA uses the PCI9056 Bus Mastering PCI interface from PLX. The PLX9056 is a
32bit/66Mhz PCI Master that has a 32bit/66Mhz local bus.
FPGA: The PTA uses the Xilinx 4VLX25 Vertex4 FPGA. The Vertex4 series FPGA’s have
built in LVDS termination resistors that save PCB space and make it much easier to
change designs.
LVDS Ports: The PTA has 4 I/O connectors. In the default PTA configuration the 4
ports will be configured for differential LVDS. The LVDS termination resistors can
be turn on and off inside of the Xilinx FPGA: No resistors will have to be
placed/removed when the PTA is used for a different test stand.
Each connector has 18 pairs of signals, and grounds. The signal pairs can be used as
18 differential pairs or 36 singled ended signals.
Memory: The PTA has two banks of 8M ZBT memory that runs up to 266MHz. The Xilinx
FPGA has 1.3Mbits of memory.
USB: The PTA uses the Cypress FX2 USB2.0 interface chips. The PTA has a connector
for an external power supply so it can be power out of a PC. The PC will then be
able to use the PTA through the USB port. The Cypress FX2 chips have transfer rates
above 20MB/s.
Miscellaneous: The PLX9056 is be able to boot the Xilinx FPGA via the JTAG port. The
Virtex4 FPGA has LVDS SERDES ports. Each port has TX data and clock pairs and RX
data and clock pairs. Depending on the speed grade of the FPGA, the SERDES can run up
to 1Gbit/Sec.
