twepp – vienna – september 27 th 2011

11

TWEPP – Vienna – September 27th 2011

Wideband (500 MHz) 16 bit Dynamic Range Current Mode Preamplifier for

the CTA cameras

D. Gascóna, A. Sanuya, J. M. Paredesa, Ll. Garridoa, M. Riboa, X. Sieirob

Universitat de Barcelona

Institut de Ciències del Cosmos ICC-UB (a)

Departament d’Electrònica (b)

1

22

I. Introduction

II. PreAmplifier for CTA (PACTA)

III. Input stage

IV. Current gain stage

V. Transimpedance stage

VI. Noise

VII. Test results

VIII. Conclusions.

Outlook

3

~ 10 kmAir shower

~ 1o

Che

renk

ov li

ght

~ 120 m

Gamma ray

I. Introduction: Cherenkov telescopes

3.5o FOV càmera 577 PMTs3.5o FOV càmera 577 PMTs

MAGICCamera by IFAE

M. Martinez

Stereoscopy provides better:•Angular resolution.•Energy resolution (height).•Background rejection.•Sensitivity.

4

Artist view of CTA-NorthKari Nilsson

I. Introduction: the Cherenkov Telescope Array (CTA) observatory

10-14

10-13

10-12

10-11

10 100 1000 104 105

E x

F(>

E)

[TeV

/cm2s]

E [GeV]

Crab

10% Crab

1% Crab

GLAST

MAGIC

H.E.S.S.

CTA

Exploring the cutoff regime of cosmic

accelerators

Population studies, extended sources and,

precision measurements

High redshift AGNand pulsars

10-14

10-13

10-12

10-11

10 100 1000 104 105

E x

F(>

E)

[TeV

/cm2s]

E [GeV]

Crab

10% Crab

1% Crab

GLAST

MAGIC

H.E.S.S.

CTA

10-14

10-13

10-12

10-11

10 100 1000 104 105

E x

F(>

E)

[TeV

/cm2s]

E [GeV]

Crab

10% Crab

1% Crab

GLAST

MAGIC

H.E.S.S.

CTA

Exploring the cutoff regime of cosmic

accelerators

Population studies, extended sources and,

precision measurements

High redshift AGNand pulsars

How CTA aims to extend energy range and increase sensitivity? Large array (>1 km2)of Cherenkov telescopes (50-100): over 100K channelsDifferent sizes: dish from 6 to 24 m

Camera and electronics must be optimized in terms ofPerformanceCost and reliability: integration

5

Preamplifier SignalConditioning

PhotoSensor

Digitization

Camera Pixel Front end electronics

Read-out

I. Introduction: the camera

Front end electronics: Pixel: fast photosensors

High QE PMTs (baseline) // SiPM Modularity: cluster of 7/8 pixels Front end electronics in the camera Digitization & trigger

Huge dynamic range: 16 bits Signals up to 5 Kphe Single phe resolution for calibration:

Noise 1/8 phe PMT gain 40Ke ENC 5Ke (10 ns integration)

PM tube

Voltage dividerDC-DC converter

HV control cable

HESS cluster

5

High BW (>300 MHz, full

chain):Night Sky Background:

Up to 100 MHz Minimize integration time

Simulation (S. Vorobiov)

This work

66I. Introduction: requirements

To develop a generic preamplifier valid for any CTA camera Common component: low cost and reliability for mass production

This component must fulfil a set of demanding requirements:

Low noise Good single photoelectron resolution at PM gain of 4·104

High dynamic rangeFrom < 1/8 of phe to 5 Kphe: 16 bitsGood linearity (< 3% nonlinearity)

High BW500 MHz. Total BW including FE must be 300 MHzFor fast read-out option

Low input impedanceLow pick-up noise and high BW: very close to PMT Compatible with SiPM

Low power About 100 mW with low impedance driver (cable, tline)

Reliability/compactness Mass production, Integrated circuit, ASIC

77

II. PreAmplifier for CTA (PACTA): circuit design

• Basic circuit: Super common base input

Low noise / High DR: used in LHC calorimetry Cascode current mirror with CB feedback Fully differential transimpedance amp.

(TIA)

• Performances BW > 500 MHz Low Zi < 10 Ohm up to > 500 MHz Low noise (in=10 pA/sqrt(Hz)) Differential: optimal CMRR and PSRR

• But the current mirror can not stand a 1000 phe pulse Limited to 12/13 bit DR Saturation at 500 to1000 phe

• Not enough for 16 bit…

7

Simplified schematic

Q1

Re

Ib1Ii+

Q2

Rc

M2M1

M2cM1cVcas

CC

Vb

Iba

QF

Q1

Re

Ib1

Vcc

Ii-Q2

Rc

M2 M1

M2c M1cVcas

CC

Vb

Iba

QF

Rf Rf

Vo-Vo+

+

+

-

-

88

II. PreAmplifier for CTA (PACTA): circuit design

• Previous circuit is modified to split the input current:– Current is divided in the common base stage– Different current mirrors for high and low gain

• Each can be optimized for BW / linearity– Dedicated saturation control circuit is added to the HG

mirror• Current division remains operational even if HG mirror saturates• Saturation threshold of HG mirror can be controlled

– Range: > 6000 phe • True delta pulse with 500 MHz BW • No arrival time effect considered

8

Patent pending

Simplified schematic

Single ended and differential versions

M2M1

High Gain

M2M1

Low Gain

SATURATIONCONTROLCIRCUIT

+

-

+

-

Common base (gate) stage with

current division n:1

n 1 High Gain

Low Gain

99

II. PreAmplifier for CTA (PACTA): prototypes

AMS SiGe 0.35 um techno:– High speed, low noise and

offset HBTs– 5 V / 30 GHz NPN HBTs– 3.3 V power supply:

• DR vs power trade off

9

PACTAv1.2 chip 2 mm2

QFN32 packageSubmitted June 2011

• An input stage + current amp. block

• A complete differential PACTA:– No low impedance driver

• 2 single ended PACTAs• 1 differential PACTA• Main modifications

– New OpAmp (s.e. and fully diff. versions): • Low output impedance stage• Higher Slew Rate (1 V/ns)

– Improve compensation of input stage and current amplifier

PACTAv1.1 chip 2 mm2

QFN32 packageBack from foundry Oct. 2010

10

1i PAD Qf mQf f CC C c g R C

1

1

1 1 1

( )1 1 1

1 //

mQmQf E i

Q

i mQ E Q Rf f Q Rf E

gg s R C

cT s

s s sC g R c c R c c R

Q1 Q0

IPD

Node a Node bHigh Gain Low Gain

QC1 QC0

VbCas

Rbias

RS

CPAD

x14

x14 x1

x1

Qf

RESD

CCRf

Vccb

10

III. Input stage

• Super common base: low Zi (<15 )• Two unbalanced current outputs:

– Vbe of Q1 and Q0 is the same– Q1 = 14 * Q0: current splitting

• Cascode transistors to improve linearity:– Minimize variation of Vc of Q1 and Q0– Minimize Early effect

• HF feedback loop (Return Ratio T(s)):– Miller compensation Cc: pole splitting– Q1/Q0 emitter degeneration RE:

• Linearizes Zi and improves matching• Limited by DR and noise: tradeoff

10

T(f) (mag) vs Cc

T(f) (phase) vs Cc

Phase Margin of T(f) vs vccb

GBWP of T(f) vs vccb

Cc=0

Cc=750 fF

1

1

1

EmQ

imQf f

RgZ

g R

With pole splitting:

Dom. Pole Zero in Zi(s)At f >2 GHz

1111

III. Input stage

• Input impedance depends on Vccb

– gmQf

11

• No impact of dominant pole on Zi

– Dominant pole also affects open loop Zi

– No inductive effect in the BW of interest

Zi(f) (mag) vs Cc

Zi(f) (phase) vs Cc

Zi(f) (mag) vs vccb

Zi(f) (phase) vs vccb

1

1

11

1

1

( )

Q Rf

Q Rf f

i

mQmQf Q

Q

c c sc c R

Z sg

g c sc

Using Blackman´s impedance formula:

zZi

pZi

pZizZi

1212

III. Input stage

• Bonding inductance must be considered: – QFN32 package: < 1mm bond wires– Series resonance: CPAD*Lb (input induct.)– Rs to increase (damping factor) – On chip decoupling cap. also need damp. res.

• Ground inductance Lg is critical:– Direct feedback to Qf emitter

• Output driver provides large current pulses: – Ringing or oscillation possible!

– Downbonds to package cavity • < 0.5 mm wires

– Multiple grounds, different grounds for:• Input stage• TIAs

12

T(f) (mag) vs Lb

T(f) (phase) vs Lb

T(f) (phase) vs Lg

T(f) (mag) vs LgT(f) (mag) vs CC

T(f) (phase) vs CC

Nominal inductances

1313

IV. Current amplifier: saturation control circuit

• Low voltage cascode current mirrors – Local feedback: common base HBT Qcb

• Minimize input impedance

• Minimize Voltage variation of VCQ1

• Wideband amplifier with high DR:– BW > 500 MHz

– Current gain (AI): 2.5

– > 12 bit DR

• But M1/M1c to ohmic region for large signals: – Feedback and low input impedance are lost

• Saturation ctrl circuit “quenches” large signals:

– Qoc1 is controlled by the voltage Vc-Vm

– For low currents Vc-Vm<<Vbe_On

– If drain current of M1 increases, Vc increases and

Vm decreases

– Turn on point of Qoc1 can be tuned through Vlim

13

M2M1

M2cM1c

Iba

Vb Vcas

Qcb

Qoc1

Saturationcontrolcircuit

Vm

Vc

M3

M3c

VlimTo collector of Q1

(Input stage)

1

1

1inMIRmQcb cF mM

Zg Z g

1414

IV. Current amplifier: saturation control circuit

• Feeback loop must be compensated

– Two main poles related to M1 gate and input nodes

– Add Cc for dominant pole comp• Drawback: limits amplifier BW

– BW limited by Cin• Must increase Cc to compensate

• BW > 500 MHz provided that:– Cin < 700 fF– With PM > 65 deg

• Source degeneration (RSM) in v1.2

– For large bias currents (or with a

high pulse rate) gmM1 increases

– GBW increases and PM decreases– Source degeneration limits the

effective value of gmM1

14

0

100

200

300

400

500

600

700

800

900

0 500 1000 1500 2000 2500 3000 3500

Cin [fF]

BW

[M

Hz]

0

500

1000

1500

2000

2500

3000

Cc

[fF

]

BW [MHz]

Cc for PM=65 deg [fF]

1( )

1 1

mM cFMIR

INcF cF

mQcb

g RT s

CsR C s g

1 2 ...cF C gsM gsMC C C C

1515

V. TIA

• Single ended and fully differential versions• OpAmp architecture:

– HBT input pair + folded cascode– Miller gain stage– Output stage:

• None for PACTAv1.1• Low impedance class AB (v1.2)

• Differential OpAmp with CMFB: – Gain > 65 dB– GBW> 700 MHz– PM > 70 deg– SR = 1 V/ns (PACTAv1.2)

• Low output impedance push-pull stage:– Based on NPN HBTs– Feedback loop must be extremely fast– Compensation is critical:

• Operates in closed loop (OpAmp output stage)

– Drives 50 Ohm loads (AC coupled)

15

x14

Qfol Qfols

x2

RSENSE

MPs

Q1

Vbef

x16

CC

Class AB output stage

Provides up to 20 mA peak current with 5 mA quiescent current

Thanks to J. Lecoq, E. Delagnes and P. Moreira

Compensation of the local FB loop Return Ratio T(f) versus Vbef

Post layout simulation including bonding inductances

PM of T(f)

GM of T(f)

GBW of T(f)

UnityGainFreq of T(f)

1616

VI. Noise

• For the single ended version• Series Noise

– Dominated by the input stage• Paralllel Noise:

– Significant contribution of• Input stage• Current mirrors

• Parallel noise dominates for Cin<5 pF

16

22 1 2

4 8n bbQf S ESDmQf

e KT r R R nV Hzg

22

2 1

1 1

2

1 21 4

1 3

4.2

mMnMIR SM

I mM SM mM

gi KT R

A g R g

pA Hz

22 24

2 8.4n BQf nMIRbias

KTi qI i pA Hz

R

1717

VI. Noise

• Differential version: uncorrelated noise sources add in quadrature

– Noise should be sqrt(2) higher• Integrated output noise referred to an

input current noise source– Equivalent noise current (ENI)– Minimal for low cap. sensors (PMT): in– Still quite ok for high capacitance sensors

17

Equivalent Noise Current (ENI)

0,0E+00

2,0E-07

4,0E-07

6,0E-07

8,0E-07

1,0E-06

1,2E-06

1,4E-06

1,6E-06

1,8E-06

0,10 1,00 10,00 100,00 1000,00

Cin [pF]

EN

I [A

rm

s]

Single Ended

Differential

en=1.13 nV/sqrt(Hz)

in=11.8 pA/sqrt(Hz)

PMT SiPM, LAAPD

1818

VII. PACTAv1.1 chip test results

Pulse shape

Input current pulse

-1,20E-02

-1,00E-02

-8,00E-03

-6,00E-03

-4,00E-03

-2,00E-03

0,00E+00

2,00E-03

10 12 14 16 18 20 22 24 26 28 30[ns]

[A]

-1,49E-04-2,79E-04-4,17E-04-5,58E-04-6,97E-04-8,38E-04-1,67E-03-2,48E-03-3,35E-03-4,11E-03-5,49E-03-6,80E-03-8,21E-03-9,60E-03-1,10E-02

PACTA high gain output for different input pulse amplitudes

-1,60E+00

-1,40E+00

-1,20E+00

-1,00E+00

-8,00E-01

-6,00E-01

-4,00E-01

-2,00E-01

0,00E+00

2,00E-01

4,00E-01

10 15 20 25 30 35 40[ns]

[V]

150 uA pp280 uA pp420 uA pp560 uA pp700 uA pp840 uA pp1.67 mA pp2.48 mA pp3.35 mA pp4.11 mA pp5.49 mA pp6.8 mA pp8.21 mA pp9.6 mA pp11 mA pp

PACTA low gain output for different input pulse amplitudes

-7,0E-01

-6,0E-01

-5,0E-01

-4,0E-01

-3,0E-01

-2,0E-01

-1,0E-01

0,0E+00

1,0E-01

10 12 14 16 18 20 22 24 26 28 30

[ns]

[V]


1919


Pulse shape (normalized waveforms)

Normalized input signal

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

0,90

1,00

10 12 14 16 18 20 22 24 26 28 30[ns]

-1,49E-04-2,79E-04-4,17E-04-5,58E-04-6,97E-04-8,38E-04-1,67E-03-2,48E-03-3,35E-03-4,11E-03-5,49E-03-6,80E-03-8,21E-03-9,60E-03-1,10E-02

PACTA normalized high gain output for different input pulse amplitudes

-0,4

-0,2

0

0,2

0,4

0,6

0,8

1

1,2

10 15 20 25 30 35 40

[ns]


PACTA normalized low gain output for different input pulse amplitudes

-2,00E-01

0,00E+00

2,00E-01

4,00E-01

6,00E-01

8,00E-01

1,00E+00

1,20E+00

10 12 14 16 18 20 22 24 26 28 30

[ns]


2020


Frequency response Small signal BW exceeds 500 MHz both for high gain and low gain Minimize peaking for LG in final version

Gain for different signal levels (Low Gain)

0,00

10,00

20,00

30,00

40,00

50,00

60,00

70,00

10,00 100,00 1000,00

Frequency [MHz]

Gai

n [

dB

Oh

m]

66 uApp

133 uApp

266 uApp

533 uApp

750 uApp

Gain for different signal levels (High Gain)

0,00

10,00

20,00

30,00

40,00

50,00

60,00

70,00

10,00 100,00 1000,00

Frequency [MHz]

Gai

n [

dB

Oh

m]

33 uApp

75 uApp

110 uApp

160 uApp

230 uApp

21

Transimpedance gain (charge)

1,0E-12

1,0E-11

1,0E-10

1,0E-09

1,0E-08

1,0E-07

1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01

Input peak current [A]

Inte

gra

l o

f th

e o

utp

ut

pu

lse

[V

s]

High Gain

Low Gain

21


Transimpedance gain (integral of the pulse) and linearity HG about 1 KOhm LG about 50 Ohm Relative non-linearity error < 2 %

100x(Meas-Fit)/Fit

1 phe

100 phe

Transimpedance gain (charge)

0,0E+00

1,0E-09

2,0E-09

3,0E-09

4,0E-09

5,0E-09

6,0E-09

7,0E-09

8,0E-09

0,0E+00 5,0E-03 1,0E-02 1,5E-02 2,0E-02 2,5E-02 3,0E-02


Inte

gra

l o

f th

e o

utp

ut

pu

lse

[V

s]

High Gain

Low Gain

Relative error of the integral of the output pulse

-10

-8

-6

-4

-2

0

2

4

6

8

10

1,0E-06


Re

lati

ve

lin

ea

rity

err

or

[%]

High Gain

Low Gain

2222


Dedicated board with PMT (R81619mod) Additional voltage gain (14.4 V/V)

Total gain TIA gain is 14.4 KOhm To minimize the impact of following stages on the input ref. noise

Differential to single ended conversion + 50 Ohm driver Lot of work on grounding and shielding Many thanks to:

R. Mirzoyan, D. Fink, P. Nayman and F. Toussenel

x14

x14LG

PACTA

Drv

Drv

HG 50 Ohm

50 Ohm

3.3V

1.8V

LDO

PM + Divider

100 nF

Prot100 nF

Diff to single ended+

50 Ohm driver

2323


Single photoelectron spectra at 900 V PMT at 900 V, gain about 4x104

New analysis method (R. Mirzoyan) with less systematic under development Integration time: 10 ns ENC of about 5000 electrons (11.8 pVs / q x 14.4 K) S/N = 8

PACTA + 20GS/s DPO Scope PACTA + NECTAr0 chip (see poster session)

2424


Input referred noise as function of the integration time Theoretical and measured noise (with and without PMT) Still some few hundred e contribution of pick up noise Differential configuration to minimize CM noise

With single ended configuration theoretical ENC should be 1/sqrt(2)

0

2000

4000

6000

8000

10000

12000

0 5 10 15 20 25 30

Integration time [ns]

EN

C [

e]

PM + PACTA +THS (HV 900V)

PM + PACTA + THS (HV OFF)

PACTA +THS (no PMT)

Theo. Parallel (white) (PACTA)

Theo. Parallel (white) (PACTA + THS)

Theo. Par+ Ser(HF) + 1/f (PACTA)

Theo. Par+ Ser(HF) + 1/f (PACTA+THS)

2525


Preliminary tests with SiPM Low Zin current mode circuit are well suited for SiPM readout

DC coupling without external components We just took an available MPPC (S10931-050P)

1 V overvoltage Recovery time seems to be dominated by internal SiPM time

constant · DC coupled· Possible to ctrl each

SiPM bias with on-chip circuitry

LG

PACTA

HG

100 nF

SiPM

10 K

Vb

- HV

Vop=Vb-HV

20 ns

2626

VIII. Conclusions

• Wideband and high dynamic range current mode preamplifier for CTA cameras

• PACTAv1.1 meets most of the requirements :– Input Referred Noise< 400 nA rms– SNR for SPE spectra: 8, at the nominal PM gain (40K)– Input range: > 20 mA peak– Dynamic range: 15.9 bits– Relative linearity error for charge measurements: < 2 %– BW: 500 MHz. Both for HG and LG– Input impedance: 10 to 15 Ω. For full BW.

• A cable / tline driver has been implemented in PACTAv1.2 – Single ended and differential versions– Power consumption: 150 mW

• Factor 3 or 4 smaller than current prototypes build with COTS

• New versions of the circuit for SiPM readout are under development

– Potentially, good time resolution

262626

TWEPP – Vienna – September 27th 2011 D.Gascón

2727

Back-up

2828

V. Noise: noise variance at the output of the system

• Noise PSD at the output depends on the transfer f unction of the system:

• The noise power is obtained integrating the output PSD:

• I n HEP the noise is usually studied in time domain (useful).• Noise process (white): series of random (Poisson) Dirac

impulses (t).• Noise weighting f unction: contribution at the output at the

measurement time to of noise impulse at t i:

– For time invariant shaper it is the mirror of the impulse response:

• The noise variance (or power) at the output is:

2 22 2 2

0 0 0y yy x xE G f df G f S f df G f e f df

2

yy xxG f H f G f

2 2 20 0

1 1

2 2G w t dt G h t dt

0

0 , i i t tw t t h t t h u

0 , iw t t

2 20 0 0

1,

2 i it G w t t dt

f or time invariant:

2929

V. Noise: time domain analysis

• Time variant system: compute w(to,t i): use definition!• Pre-shaper f unction p(t): source impedance and preamplifier!

– Diff erent f or series and parallel noise– But all fi rst order system with < 4 ns.

• w(to,t i) at the end of integration (to=t1+tR):– Shaded area of the impulse arriving at t i.

• Analytical expression f or our system (tR=T):1.Noise impulse arriving af ter end of integration (ti>t1+T ):

w(to=t1+T,t i)=0.

2.Noise impulse before start of integration (ti t1 ):

3.Noise impulse af ter start of integration (ti > t1 ):

-60 -40 -20 20

0.2

0.4

0.6

0.8

1w(ti)

ti [ns]

RR

tQ CT

time-invariant pre-shaper

p(t)b

aA gated

integratorp(t)

p

R

p t1 t1+ R

ti=t1-tp

ti=t1+tR

p

pW(to=t1+ tR,ti)

to=t1+ tRti

ti

ti=t1

1 1

1

10 1 1,

i ii

i

t t t T tt T t

i it ti i

A Aw t t T t p x dx e e t t

1

1

0 1 1 10, 1

ii

t T tt T t

i ii i

A Aw t t T t p x dx e t t t T

1( )

t

p t A e u t

< 4 ns

10 ns 5 ns 1 ns 0,5 ns

0,1 ns

w(t0,ti) fordifferent

TIME [ns]

3030V. Noise: time domain analysis

• The noise variance is:

• For T>>:

2

2 20 1

11

2

T

white niwhitei

At t T e T e

2

2 20 1

1

2white niwhiteTi

At t T e T

Approximation error as

function of

3131II. Noise requirements

Good single photoelectron resolution: S/N > 10 in the charge spectra

How to translate to typical specification for amplifiers? Series (en) and parallel (in) noise power spectral densities

Assumptions Flicker noise is negligible Current preamp: RPM open Voltage preamp: ZT resistive (RPM) CPAR is small enough: series noise negligible for I amp RPM is small enough: parallel noise negligible for V amp

Noise variance at the output of gated integrator is (approx): T is the integration time

2 2 21

2no niG Te

ZT

eZT

RSeRs

en

in Zi

Iin

IPMT

I preamp: VO=ZT·Iin

V preamp: VO=G·Vin

Vin

ZT = RPM // CPAR

2 2 21

2no T niZ Ti V preamp: I preamp:

32

0,00E+00

5,00E-12

1,00E-11

1,50E-11

2,00E-11

2,50E-11

3,00E-11

3,50E-11

5 10 15 20 25 30

in [A

/sqr

t(H

z)]

Integration time T [ns]

Low gain (40K)

High gain (100K)

32II. Noise requirements

For a voltage preamplifier, the signal at the output of gated integrator is Zi is the PM load impedance

And the S/N is

Max input referred noise of the amplifier (en):

For a S/N > 10

2· ·

·i phe

Vni

Z QSN T e

2· ·

·

i pheni

MIN

Z Qe

ST N

0

2E-10

4E-10

6E-10

8E-10

1E-09

1,2E-09

1,4E-09

1,6E-09

1,8E-09

5 10 15 20 25 30

en [V

/sqr

t(H

z)]

Integration time T [ns]

Low gain (40K)

High gain (100K)

Voltage amplifier Current amplifier

< 1 nV/sqrt(Hz) ! < 10 pA/sqrt(Hz) !

· ·o oA iA i iA iS v dt Gv dt G Z i dt Z G Q

3333III. The ATLAS LAr preamplifier

Low noise Series noise: en=0.36 nV/sqrt(Hz) Parallel noise: in=6.7 pA/sqrt(Hz) Low gain option: 40 K

Low noise preamplifier is needed

High dynamic range: about 14 bits

Super-common base: Small input impedance Photo-detector current is sensed

3434IV. Measurements

Single photoelectron spectra

Pulser LED @ 460 nm < 500 ps FWHM

Afterpulsing observed

LASER @ 640 nm < 50 ps FWHM

Optical attenuator

Hamamatsu R7600 PM To be repeated with R9420


Single photo-electron spectra @ HV = 500 V : 40 K gain

• Preamp noise: 3-4 Ke, limited by common mode and pick-up

noise

PM HV500 VSingle

photoelectron


Effect of the integration time

0,00E+00

1,00E+03

2,00E+03

3,00E+03

4,00E+03

5,00E+03

6,00E+03

5 10 15 20 25 30


No

ise

[e]

Measured Noise [e]

Theoretical White Noise [e]

3737

IV. Measurements: conclusions and plans

• Super common base architecture is promising– Low noise

– High dynamic range

– Low input impedance

• However covering full dynamic range with a single preamplifier is still difficult:

– Preamp saturation (for LAr preamplifier) • 5 mA

– Max signal (6 Kphe) • 20 mA peak current @ 40 K gain

37

3838


Low inductance QFN socket Test PCB with socket for characterization Noise/single phe measurement:

Dedicated PCB with Additional gain 50 ohm drivers

Test set-up:• Agilent 81155A pulse generator

• HP RF signal generator (DC-1GHz)

• Picoquant Laser Pulser (50 ps FWHM)

• Tektronix TDS7154B scope: • 1.7 GHz

• 20 GS/s

• Active differential probe: 1 GHz

39

Transimpedance gain (peak to peak)

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

1,00E+01

1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01


Out

put

peak

vol

tage

[V

]

High Gain

Low Gain

39

III. PACTAv1.1 chip test results

Transimpedance gain (amplitude) and linearity HG about 1 KOhm LG about 50 Ohm Relative non-linearity error < 3 %

100x(Meas-Fit)/Fit

1 phe 100 phe

Transimpedance gain (peak to peak)

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

0,0E+00 5,0E-03 1,0E-02 1,5E-02 2,0E-02 2,5E-02 3,0E-02


Ou

tpu

t p

ea

k v

olt

ag

e [

V]

High Gain

Low Gain

Relative error of the amplitude of the output pulse

-10

-8

-6

-4

-2

0

2

4

6

8

10

1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01


Re

lati

ve

lin

ea

rity

err

or

[%]

High Gain

Low Gain

4040

III. PACTA chip test results

PMT signal shape

2.1 ns

PACTA OutputHV=1200 V

PMT directly to scope

PACTA OutputHV=900 V

4141


Gain is calibrated for single photoelectron spectra, comparing: Single photoelectron signals with no preamp, direct to scope (only high

gain) Single photoelectron with PACTA Result is quite close to what we expect: 14.3 Kohm

1,00E+04

1,00E+05

1,00E+06

1,00E+07

100 1000 10000

HV [V]

R8

61

9 m

od

ga

in

PM to Scope

PM + PACTA

0,00E+00

1,00E+05

2,00E+05

3,00E+05

4,00E+05

5,00E+05

6,00E+05

7,00E+05

8,00E+05

9,00E+05

1,00E+06

1,10E+06

1,20E+06

1,30E+06

1,40E+06

1,50E+06

850 950 1050 1150 1250 1350 1450 1550

HV [V]

R8

61

9 m

od

ga

in

PM to scope

PM+PACTA

4242


S/N ratio for single photoelectron measurements Optimal integration time is the which maximizes S/N: about 10 ns

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

8,00

9,00

10,00

0 5 10 15 20 25 30


S/N

PACTA +THS (No PMT)

PM + PACTA + THS (HV OFF)

PM + PACTA + THS (HV 915 V)

Theo. (PACTA)

Theo. PACTA + THS)

4343

III. PACTAv1.1 chip test results

Preliminary tests with SiPM

Bi-gain is also working

4444


Preliminary tests with SiPM

Charge spectrum

4545

PACTA Connections

Different scenarios: location and connection to FE PMT cluster as single board

No pb to place preamp very close to PMT (< 3 cm) PACTA to FE connection:

Differential impedance controlled PCB traces Cheap and robust

PMT cluster in several boards: PMT – cable - PACTA PACTA Zin is 10-20 Ohm: no adapted If distance between PMT and PACTA increases: EMC…

Preliminary test shows than 10 cm could be ok What is the min length that cluster design can achieve?

PACTA to FE connection: Differential impedance controlled PCB traces

PMT cluster in several boards: PMT – PACTA – cable(s)

PACTA can be very close to PMT but… Room for PACTA + test pulse + monitoring … ???

+ CABLES and connectors ??? How many ? NOT RECOMENDED

PMT

PACTA FE

PM cluster in single board

< 3 cm

PMT

PACTA FE

PM cluster in several boards (A)

Length ???

CablePCB trace

PMT

PACTAFE

PM cluster in several boards (B)

How many cables ???

4646

IV. PACTAv1.2

• A fully differential TIA and 2 single ended TIAs Each of them with HG and LG outputs

• New 50 Ohm drivers have been integrated Many thanks to J. Lecoq (LPC), E. Delagnes (CEA/Saclay) and P. Moreira (CERN) Class AB push-pull follower with fast local feedback Dynamic range to directly match std differential ADCs:

1 V for single ended version 2 Vpp for fully differential version

Total power consumption : 120 – 150 mW For 2 (High and Low gain) differential outputs To compare with COTS solution

Preamp FE amplifiers: double gain + level adaptation Power consumption reduction: 500 mW /ch (aprox)

• Single ended input stage for minimal noise According to simulations 1/1.2 wrt fully differential TIA

Ideally should be 1/sqrt(2) Common mode noise (bias current sources, etc)

• Minor changes on the current mode input stage: Minimize high frequency peaking Closer to a first order system response

46

PACTA1.2 chipSiGe BiCMOS 0.35umAMS 2 mm2

QFN32 packageSubmitted on June 6th

twepp – vienna – september 27 th 2011

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