fee2006 - perugia. a. rivetti a fast large dynamic range shaping amplifier for particle detector...

FEE2006 - Perugia. A. Rivetti

A FAST LARGE DYNAMIC RANGE SHAPING AMPLIFIER FOR PARTICLE

DETECTOR FRONT-END A. Rivetti – P Delaurenti INFN – Sezione di Torino


Project framework

Development of a fast binary read-out chip for Compass at CERN

Chip designed to replace an older ASIC (MAD4) in the RICH upgrade

User requirements:

Preserve the compatibility with the existing read-out

Reduced gain for MPT read-out

Threshold adjustable channel by channel

Hit rate > 5 MHz

Power consumption < 30 mW/channel

From 0.8 um BiCMOS to 0.35 um CMOS


ASIC overview

FE

DACb0

b7

One shot LVDSin

out +

out -

FE

DACb0

b7

One shot LVDSin

out +

out -

FE

DACb0

b7

One shot LVDSin

out +

out -

FE

DACb0

b7

One shot LVDSin

out +

out -

FE

DACb0

b7

One shot LVDSin

out +

out -

FE

DACb0

b7

One shot LVDSin

out +

out -

Variable gain front-end Fast comparator 8 bit DAC Programmable one shot LVDS driver LDO


Front-end building blocks

PreampOTA

BLHVref_blh

-

+Vref_OTA

inVout

PreampOTA

BLHVref_blh

-

+Vref_OTA

inVout

Variable gain preampRail-to-rail output shaperContinuous-time baseline restorer


A typical core amplifier

Commonly used in preamp and shapersSource follower has limited swing Asymmetrical slew-rate


Example of slew-rate requirements

Vout (V)

dt

Fast shaping time require slew rates of the order of 100 V/s.

Example: 2.5 V @ 10 ns peaking time requires 400 V/s.

Particularly critical if off-chip loads have to be driven.

In class A, for 10pF 4mA of bias current0 210 -8 410 -8 610 -8 810 -8 110 -7

0.5

1

1.5

2

2.5

3

0 2 1́0-8 4 1́0-8 6 1́0-8 8 1́0-8 1 1́0-7

-4 1́08

-3 1́08

-2 1́08

-1 1́08

0

1 1́08

dV (V/sec)

time (s)


Better output stages

Vout

Vin

Vbias

Zero Vt devices!

Very simple Class AB Requires special devices No rail-to-rail (Vds,sat+VTH)

Rail-to-rail More complex class AB control No special devices rail-to-rail (2Vds,sat)

Vout


Class AB control circuit

D. M. Montecelli, IEEE JSSC, Vol. SC-21, Dec. 1986Hogervost et al., IEEE JSSC Vol. 29, No. 12, Dec. 1994.

Vout

Vin1

Vin2

IB/2 IB

IBIB/2

Minimum current 0.3 Iq Maximum current >> Iq


Complete op-amp


Simulated slew-rate performance

Output pulse with 10pF load (blue curve) and 100pF output load

time (s)

Out

put v

olta

ge (

Vol

t)


Pulse shape tuning

Out

put v

olta

ge (

Vol

t)

time (s)

Output pulse with 10pF load and reduced compensating capacitors


Critical components


From the literature (1)


From the literature (2)


BLH block diagram

-

+Vref_OTA

Vout

Vref_BLR

From preamp

-

+ Closed loop bufferwith slew rate limitation

Gm stage

Class AB OTA


Behavioral simulation

Optimization driven by an analytical model of the full chain in Mathematica

SR limitation modelled in the time domain


Full circuit model

Analytical model of the full chain to simulate accurately baseline shifts


Baseline drift with Gm-stage only

Analytical model

Baseline drift smaller owing to SR limitation in the Gm-stage (not modelled)

Spice simulation

Simulation with random arrival time


Effect of the buffer

With SR-limited buffer-Spice

Analytical model with SR-limitedBuffer (zoom around baseline)

Without SR-limited buffer-Spice


Gm-stage schematic

Vbias

Vin 1 Vin 2Iout


SR-limited buffer schematic


BLR layout

400 m

200 m


First prototype results

Linearity

Peaking time

ENC 1450 e-@10pF

Credits due to Michela Chiossofor the tests of the chip!


Exploring the critical region

0 fC 900 fC


“Curiosity driven” simulations in 0.13 m

Same class AB topology scaled down to 0.13 m and powered at 1.2 V


Pulse shape with 10 pF and 100 pF loads

10 ns

810 mV

12 ns

895 mV

10 pF output load 100 pF output load

VBLH

inVout

R2

R1

Csh R2/R1=4 Csh=240 fF power = 800 W


Linearity in 0.13 m


Low voltage class AB control

Vout Vin 1

Vin 2

K. J. de Langen, J. H. Huijsing. IEEE JSSC, Vol. 33, No. 10, Oct. 1998.

fee2006 - perugia. a. rivetti a fast large dynamic range shaping amplifier for particle detector...

Documents

fee2006 perugia

vout slide

rivetti effect

torino slide

shifts slide

time domain slide

rivetti example of slew

rivetti baseline drift