First results from PADI-2 Mircea Ciobanu CBM Collaboration Meeting March 10 –13, 2009 GSI-Darmstadt FEE1

Outline  Status of the RPC-Front End Electronics  First results of the PADI2 (4ch) prototype: a) Gain, linearity, noise, bandwidth, time over threshold behavior a) Gain, linearity, noise, bandwidth, time over threshold behavior b) Timing performance b) Timing performance c) Measurements with the TACQUILA3 digitizer c) Measurements with the TACQUILA3 digitizer d) Crosstalk, Common Mode Rejection Ratio d) Crosstalk, Common Mode Rejection Ratio e) Input impedance and reflections e) Input impedance and reflections  Summary and Outlook

FEE Status (February 2009) 1.We have prepared 6 PADI1 test plates for tests together with different detectors. In order to have a easy access to NIM-CAMAC systems, 6 interfaces LVDS-PECL are ready for use. 2.From the tests of PADI1 prototype, we have recognized that the increase of the separation between channels is the main priority. In the new design of PADI2 we have changed the biasing type from voltage to current. We have increased to 4 the number of channels and we have added the OR feature which allows to daisy-chain chips for trigger purposes. We have designed two variants PADI2 and PADI3 which slightly differ in output LVDS levels. 3.The new ASIC – PADI2,3 was submitted in October 2008 and we have received about 30 pcs. dies. 4.With the first two samples we performed a basic functionality tests. From this elementary tests we can conclude that 4.With the first two samples we performed a basic functionality tests. From this elementary tests we can conclude that all channels are fully operational. 5.We have designed a test PCB, which is able to be Data Acquisition system and the first results will be presented. 5.We have designed a test PCB, which is able to be directly connected with our TACQUILA3 Data Acquisition system and the first results will be presented. 6.We started a detailed technical characterization of the first samples and first results will be presented.

PADI1 Test PCB and the LVDS-ECL adaptor PCB

PADI2 Preamplifier-Discriminator: Block Schematic NEWS

PADI2 is bonded directly on the test PCB

PADI2,3 Test PCB

DC Measurements 1: I DC chip and Power/Channel dependence to R EXT Nominal Operating Point for Z IN =50  for Z IN =50 

DC Measurements 2:

Linearity: Pulse Measurement

Time over Threshold behavior

PADI2#1; AC Transmission Measurement  The nominal working point of the PADI2-PA: G PA =38.8dB, f L =2.8MHz, f H =288MHz with par.:G PA P=37.8dB fL=2.4MHz, fH=215MHz at EOut: G EO =34.5dB f L =2.8MHz, f H =230MHz with par.:G EO P=31.8dB f L =2.4MHz, f H =203MHz  f H is about 4 times less then PADI1 case! For what? PADI1 PADI2

PA-Out Simulations: Corners Nominal working point G PA =87 BW=288MHz G EO =23 BW=255MHz

EOut Simulations: Parasitic, Corners and nonlinear Load RL is nonlinear : The input impedance of the PCB Q-Buffer is strong nonlinear (1K   ) and depends of frequency CL is significant: 4-6pF for PCB traces and 1- 3pF for bonding wires. RL RL Nom.Op.PointGPA=23BW=255MHz

Noise evaluations From PADI2 Noise simulations: GainNoise at outputNoise at inputNoise equiv. PA mV RMS 24.6µV RMS 3400 e PA with Parasitic mV RMS 26.5µV RMS 3780 e

Time resolution for different threshold voltages (tests with pulses having 1.7ns at HM) Channel EOut Offset = +2mV Channel EOut Offset = -3.2mV

Comparison: PADI2 and TACQUILA3 versus PADI1 and (pulse width

Input Reflections: Short Pulse Method Uinp=10mV,Refl=+/-3% -30dB -6dB -6dB Y Sync TDS7104 Attenuator Directional Bridge BridgeHP8721A D.U.T -6dB PulseGen.HP8082A Splitter Z i =47  - 53  Cal: Open, 7.48mV I DC =26mA, 3.1mV 36mA, 2.2mV 46mA, 1.1mV 56mA, 0.25mV

Crosstalk: Short Pulse Measurement at Qoutput

CMRR: Short Pulse Measurement -6dB -6dB PulseGen.HP8082A -30dB Attenuator Power Splitter To Ch.+IN To Ch.-IN 2ns Lemo cables: l ~ 220mm l ~ 220mm non equals length Lemo cables:  l ~ 3.5mm matched  l ~ 3.5mm matched for max. CMRR-Ch4

 Summary - The PADI2 design was successful tested. all channels are operational. - - PADI2 in connection of with our TAQUILA3 Data Acquisition system works properly. -The first results indicate:   Time [ps]< 10   Gain ~ 80 ?   Bandwidth [MHz]~ 220 ?   Linear range [mV]~ -10 to 10   CTRR [dB]> 40   CMRR [dB]> 28   Input impedance [  ]~   Power [mW/Ch]~ 25  Outlook  The DC measurements shows  The DC measurements shows a big dispersion of the DC offsets at the output of the PA for different channels(+/-7mV). Probably is due to the low open loop gain of the feedback loop and of the non good match of the involved stages. Can be corrected?   In crosstalk measurements was pointed out a influence of the digital part to the analog one; the ground connections inside the chip must be reevaluated. .  Tests of PADI1-2 with different RPC detectors must be done.  The analog outputs are more needed?   Connection with the GSI event-driven TDC GET4 prototype must evaluated.

We acknowledge the support of the European Community- We acknowledge the support of the European Community- Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (HadronPhysics, contract number RII3-CT ).

Q Calibration

Crosstalk: Short Pulse Measurement at Eoutput

Comparison: The time resolution of all designs