ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 1

Electronics part of AHCAL calibration system

ECFA meeting at Warszawa

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 2

Proposal for calibration system

• Fast LED driver is needed for fast photodetectors…

• A tunable calibration light in the range 0 to 100MIP

• Simplification of the optical system: one LED -> one side emitting fibre, one row of scintillator tiles

• See Jara’s talk Optical part of AHCAL calibrator

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 3

Two scenarios of calibration system for EUDET AHCAL

1. Side emitting fiber for one raw, QRLed driver sitting on the side of module (endcap)

2. QRLed driver is sitting at HBU above the scintillator

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 4

Side emitting fiber version

QR driver + LED

24*3cm² area needed at the main PCB

24 fibers

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 5

Scenario with QRLed driver by scintillator

• One LED, one QRLed driver at HBU

Signals needed:

T-calib

V-calib (single ended)

power +12V

This figure is been used by Riccardo Fabbri’s talk

QRLed driver will be placed here around

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 6

Electrical block diagram of the Calibrator

QRLED 1

T-calib

V-calib

Power regulator

QRLED 24

LED1

LED24

+12V

Optical taps

- notches

- drops

# of elements compensate exp attenuation

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 7

QR LED driver, basic parameters

• Fixed pulse width 2 ÷ 10 ns

• LED is an integral part of QR driver

• Cosine waveform reduces elmag. x-talk

• PCB footprint 2 ÷ 3 cm²

• Easy power-pulsing

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 8

PIN PD response to UVLED

LED current 1V => 1A

PIN

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 9

Principal schema of QRLed driver

AA

LED

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 10

Toroidal inductors, ~ 30nH

All inductors has

Non-magnetic core

No sensitivity to external mag. field

L1L2 L3

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 11

Toroidal inductors - parameters

Inductors toroidals non magnetic core

  turns L [nH] @100kHz Q @100kHz L [nH] @50MHz Q @50MHz core

L1 6 32 1.6     PE

L2 5 20 1.7 *53nH* 95 PX

L3 7 25 1.8 *56nH* 73 PX

non mag core Polyethylen PE OD = 7mm, ID = 4mm, h = 1.6mm

non mag core Pertinax PX OD = 7mm, ID = 4mm, h = 1mm

stars ** means inductors used 2.5cm terminals to measure Q @ 50MHz

it adds about 20nH to total inductance

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 12

Toroidal inductor soldered

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 13

Toroidal inductor soldered

See thickness of PCB and inductor

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 14

LED current

• Max amplitude 1A

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 15

LED current zoomed

2ns/div

1A peak

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 16

Linearity test - preliminaryQRLED linearity

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0

V control

AD

C s

ign

al

SiPM

PMT

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 17

Conclusion

• Inductor has been changed from loop to toroidal structure

better magnetic isolation• 2 scenarios for calibration system

– QRLed driver at HEB (endcap) fibers needed– QRLed driver in detector on HBU no fibers

• At the next HCAL DESY meeting we would like to start the discussion about the integration

• It is a part of the EUDET task Multichannel LED calibration prototype

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 18

Backup slides

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 19

LED current• View of the LED

pulse for a middle amplitude (1.0 A)

• Measured with 1GHz voltage differential probe and 1GHz scope TDS4104 at 1Ω smd resistor

• 4ns/div 0.5A/div

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 20

In wider time scale

PIN

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 21

ECFA, JUN10, 2008 Ivo Polak, IPASCR, Prague 22

In wider time scale, increase of the amplitude

PIN 2mV/div