CSC Electronics Evaluation

CSC Electronics Evaluation

Alexander Khodinov and Valeri Tcherniatine

Outline Preamplifier Uniformity Study

Cross Talks : Contributions from Analog and Electronic Components

Does knowledge of XTalks improve electronic uniformity?

The characteristics of CSC preamplifier chips In order to check uniformity of CSC amplifiers the special test stand was built by Anand.

The step function shaped pulse was injected to each of 25 channels of a chip through the system of capacitors.

Totally 3720 CSC preamplifier chips were tested.

The following chip characteristics were studied:

baseline ( in Volts, V); noise (in electrons); amplitude or the gain, which is pedestal extracted peak value (V); width, which is FWHM of a positive part of a signal (nsec); current (mA).

The overall (over all chip and channel) distributions ofsignal baseline (a), amplitude (b), noise (c) and width (d)without any pre-selection.

The most critical parameter is amplitude or gain.

RMS of the amplitude distribution is about 3.1%

It makes sense to assume, that non-uniformity is partially due to a relatively large spread in test stand capacitances.

How the amplifier characteristics depend on the channel number in the chip

• The abscissa axis indicates channel number in the chip and the ordinate axis is the overall averaged values of width (a), amplitude (b), noise (c) and baseline (d) along with their error bars

• In the cases of noise and amplitude, errors are too small and lie inside dots

• Baseline and the width plots shows clear correlation between their values and the channel number, while the effects of a layout in the chip do not have a characteristic tend in cases of amplitude and noise+

+ +

+

* - influence of a layout in the chip (not studied in frames of this work)

• To exclude the effect of a spread in calibration capacitances, the same four distributions for a fixed channel number (number 5) are plotted.

• Gaussian parameter sigma of the amplitude distribution dropped by the factor of 2 to 1.5%.

Signal baseline (a), amplitude (b), noise (c) and width (d) distributions for the channel number 5 over all preamplifier chips

The scatter plot of the amplitude of the channel 0 versus the channel 5

• Since measurements of all preamplifiers took around a month, various long term factors could contribute to the channel-by-channel fluctuations.

• The scatter plot of the amplitude of the channel 0 versus the channel 5 has a shape of the ellipse (a), what makes the correlation between these two channels completely clear.

• Following to the correlation analysis the projection of the Figure (a) to the axis along the small ellipse radius (Figure b) represents the actual amplitude distribution, and its Gaussian parameter sigma = 0.97% may be taken as a conservative estimate for the preamplifier channel-to-channel gain uniformity.

Amplitude versus Width anti-correlations

Cross-Talks in ASMI-ASMII pack

A unit of CSC Electronics is the pack:

1 ASMII + 2 ASMII

ASMII (digital electronics)

has 2 Glinks, 96 channels each

ASMII

ASMI

Custom made test-bench for electronics test

Special tool is designed to inject the charge into a particular channel

Charge injected into all channels simultaneously

Analog part:preamplifier

Calibration Example

Large chamber #10. Precision strips X. No crosstalk. ROD data.

Groups of 24 channels are emphasized.

ADC/fC

ADC

COMMON / IDIVIDUAL Calibration Schema

j

jj

Aind

AindInd

Common calibration, all channels are pulsedsimultaneously, Cj-calibration capacitance;

Individual calibration, when only particular channelunder is pulsed through the special probe;

Xtalk, the ratio of common to individual;

All 96 x 2 test bed capacitanceswere measured prior to Xtalk study

Acom

Aind

C

C

Aind

Acom

Aind

AcomR

jj

j

j

jj

jj

jj C

C

Acom

AcomCom

Cross Talk is Common to Individual Ratio

Rev. E Rev. E

How stable calibrationsand cross talks are?

So next steps are

1. Check for Xtalks in early electronic revisionsof ASMI and ASMII

2. Comparison of two common andindividual calibrations taken in a few days

3. Comparison between two Xtalks taken with * different ASMIs, but same ASMIIs * same ASMII and different ASMIs * different ASMIs and different ASMIIs

The periods of 24channels are clearly seen

production Revision E

Glink B

Rev.A Left –Rev.B Right (test beam ASMI and ASMII)

Note: Xtalks of Glinks C and B

are significantly different for

different revisions under study

Rev. A Rev. B

Rev. A Rev. B

Glink C

Glink B

Comparison of two individual calibration rates (Ai/<A> -1) taken in a few days

individual 1

individual 2Production RevisionASMII – 115ASMI – 89L 88R

… and two common …

common 1

common 2Production RevisionASMII – 115ASMI – 89L 88R

Cross Talk Evaluation due to Analog and Digital Electronic Component

com03/ind03-com04/ind04

ASMII – 115 ASMII – 009ASMI – 294R 295L ASMI – 294R 295L





Large chamber #10

ROD data

Crosstalk corrections applied

No Crosstalk corrections

How XTalk Corrections improve uniformity of electronics

Example Large chamber #10. Precision strip side (X).Pedestal and Noise distributions. ROD data.

Summary

Channel-by-Channel gain uniformity of preamplifier chips themselves isless than 1%;

CSC electronic (ASMI+ASMII) readout channel uniformity is a bit worse ~1.9%;

The individual-to-common calibration ratios, which we call XTalks, have 24-channel periodic structure;

Common calibration amplitude is distorted by XTalks up to ±4 %.

XTalks are stable in time (3-7 days) and are the same within 0.1-0.3% for all ASMIs and ASMIIs inside the production revisions;

Applying XTalks to calibration routine significantly improves the electronic uniformity

Additional Slides

Channel-by-Channel Difference in test-bench capacitors

Glink B

Glink C

TB calibration study ci/<c24>-1

Rev. C Rev. B Rev. BRev.A?

Dead channels and chamber parasitic capacitances are smashed the profiles, making ASMI type recovery more difficult

Dead channels

Production summary resultson RATPAC stand-alone test bench not ROD

Documents

CSC Electronics Evaluation