Minutes of the Tracker Electronics Meeting
April 30, 2001
Present: Robert, David, Masa, Mutsumi, Wilko, Hartmut, and
Dieter
1. GTFE: Ned
submitted chip this morning.
2. MOSIS
Submissions: Robert; Robert stated that MOSIS has an intermediate prototype run
of about 100 to 1000 chips. This could cost substantially less than a wafer
run, but one has to submit a complete RFQ to find out the cost. A wafer run in the Agilent 0.5um process
costs $107,200 for 15 wafers. An
additional 15 wafers costs $48,200.
These are 6-inch wafers.
3. Comparator:
Wilko; Wilko stated he observed an offset of 500 mV on the test chip, but his
results were not stable with time. Wilko tried to use a meg-ohm resistor
instead of the bias current source. Dieter believes now that the input polarity
of the comparator (clock receiver) may be miss-labeled.
4. Shaper peaking
time: Masa; Masa stated he measured the shaper output with and without the Pico
probe. He plotted the delay difference versus the discriminator threshold
setting. David then simulated the test chip using the same thresholds and added
capacitance to match Masa's delays. The simulation needed an additional 150ff
to match Masa's measurements. This is in reasonable agreement with the
advertised capacitance of the Pico probe that is 100ff. We still don't understand the delay. See Masa’s note below and the attached PDF
file.
5. SEU: Masa; Masa
stated he and Mutsumi found that they can cause a latch-up in the TOP5 test
chip. They use a camera flashlamp to cause it to latch-up. 3 of the registers
are SEU hardened, and one is the Tanner standard cell. Robert stated it would
be good to try looking at upsets and verify that the SEU-hardened cells upset
less easily.
6. Test system:
Wilko reported that his write-up is nearly done. There will be some effort to
speed up the testing. Wilko stated that there could be some additional testing
needed. Robert stated he wants to purchase any hardware needed this year. We
need a signal generator and probe cards. Robert stated that there might be a
conflict with ATLAS with the probe station. SLAC may buy another one, however.
Hartmut and Masa will look into the probe station issues.
7. Chip
qualification: Hartmut; Hartmut stated that Nick Virmani needs to sign off on
all parts. Hartmut also stated that the SSD qualification document is
converging nicely. Nick is working with Hartmut. Robert stated the LET is more
important than total dose for the ASICs.
8. GTRC: David;
Plans to submit it to MOSIS on May 7th.
9. Test boards;
Robert; Robert stated that we need to make a 6 GTFE version of the MCM for
testing. David stated that this would be done at SLAC. Robert stated that UCSC
would make a single GTFE test board. David will make a test board for the GTRC.
10. MCM: David: David
stated there is still an outstanding issue of what kind of gold plating is
needed for the surface mount components as compared to the soft gold needs of
the wire bonding.
11. Flex cable:
David; The cable 0 flex cable is being layed out by Serge. Cable 7 is an issue
because of the narrower than expected routing area at the top connector. We
will look into this.
Masa’s note on his measurements of peaking time:
Suggested by Dave, Wilko and I did a couple
of measurements on shaper peaking time.
We measured time of rising edges of comparator outputs since the charge
injection, with and without a pico-probe on the shaper output pad. Plots are in a PDF file attached to this
message.
Here are the parameters:
AVDD
= DVDD = 2.5 V, AVDD2 = 1.5 V, Vref = 0.5 V
Bias
current: 37.7 uA into PVI1 and 2.5 uA into p500nA
Charge
injection: 2.2 fC (200 mV at the pulser, 1/200
Attenuation,
and a 2.2 pF cap)
Capacitive
load: 2.2 pF (grounded through the 50 ohm register)
From the plots, I estimated the difference
between rising times with/without a probe by comparing times at which
comparator output passes 1.25 V (50% of the DVDD voltage). One set of the cables and the conversion
chips was used throughout the measurements, so that cable/chip delays do not
affect the time difference between with and without a probe. Here is the result.
=======================================
threshold 14
mV 30 mV 49 mV
---------------------------------------
ch1 12.7 20.3 39.5
ch2
9.7 24.9 38.8
ch3 10.3 22.5 35.9
---------------------------------------
average 10.9 22.6 38.1