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VMM1 An ASIC for Micropattern Detectors. Gianluigi De Geronimo , Jack Fried, Shaorui Li, Jessica Metcalfe * Neena Nambiar, Emerson Vernon, and Venetios Polychronakos Brookhaven National Laboratory - * CERN TWEPP - September 2012. VMM ASIC family.

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Gianluigi De Geronimo , Jack Fried, Shaorui Li, Jessica Metcalfe *

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Gianluigi de geronimo jack fried shaorui li jessica metcalfe

VMM1

An ASIC for Micropattern Detectors

Gianluigi De Geronimo , Jack Fried, Shaorui Li, Jessica Metcalfe*

Neena Nambiar, Emerson Vernon, and Venetios Polychronakos

Brookhaven National Laboratory - *CERN

TWEPP - September 2012


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

VMM ASIC family

VMM: ASIC family for ATLAS Muon Spectrometer upgrade (Micromegas and Thin Gap Chamber)

  • VMM1: architecture and issues

  • VMM2: plans

VMM1

AR


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Architecture

neighbor

direct timing (ToT or TtP)

logic

or

real time address (ART)

CA

shaper

peak

mux

amplitude

time

mux

mux

timing

addr

mux

address

64 channels

logic

  • dual polarity, adj. gain (0.5, 1, 3, 9 mV/fC) (0.11 to 2 pC), adj. peaktime (25-200 ns)

  • discriminator with sub-hysteresis and neighboring (channel and chip)

  • address of first event in real time at dedicated output (ART)

  • direct timing outputs: time-over-threshold or time-to-peak

  • peak detector, time detector <1 ns

  • multiplexing with sparse readout and smart token passing (channel and chip)

  • threshold and pulse generators, analog monitors, channel mask, temperature sensor, 600mV BGR, 600mV LVDS

  • power 4.5 mW/ch, size 6 x 8.4 mm², process IBM CMOS 130nm 1.2V

CA


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Dual polarity charge amplifier

sn

1

N

sn

Ibias

CF

CF·N

sp

Qin

Qout = Qin ·N

from sensor

to virtual

ground

-∞

-∞

sn

sp

rail-to-rail output

Ibias

1

N

sp

ESD protection- issue: excessive leakage (few nA)

VA


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Front-end voltage amplifier

L = 180 nm

W = 10 mm

M = 200

ID = 2 mA

Vin

MI

inverting output stage with bootstrapping

Mc2bias circuit

MC1

MS2

MS2

VC2

MC2

comp

Vout

C

MC2

VC2

MS1

fast response to positive charge

switchable compensation

- issue: unstable when set for large caps

SC


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Gain and energy resolution

Gain vs input capacitance

ENC vs input capacitance

difference due to increased peaking time

high drop due to failing switchable compensation

disagreement part due leakage from ESD protection, part being investigated

analog dynamic range Qmax/ENC exceeds 12,000

DR


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Delayed Dissipative Feedback (DFF)

Delay feedback of dissipative element (i.e. resistor RS)

Q·N

CS

RS

CF

CS

V1

Q·N

CF·N

Vout

-∞

-∞

other poles

Q

charge gain N

shaper

DDF shaper

higher analog dynamic range

Applies also to the other stages of the shaper

see G. De Geronimo and S. Li, TNS 58, Oct. 2011

DS


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Sub-hysteresis discrimination

Comparator input stage

output

upper threshold

upper threshold

hysteresis

lower

threshold

  • Positive feedback

  • high speed at low Vi+-Vi-

  • hysteresis set NMOS ratio

hysteresis

sets minimum detectable

Sub hysteresis

1 - set window lower

  • limit reduced to overlap

  • no action on input

  • or threshold signals

2 - raise window after trigger switch NMOS ratio

hold until triggers back

PD


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Peak measurements

Large amplitude

Small amplitude

  • with sub-hysteresis

  • nominal hysteresis 20 mV

  • ~3 mV offset

  • from external buffers

TD


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Timing measurements

Uses peak-found signal

  • low time-walk

  • high timing resolution

  • sub-ns timing

  • ns time walk (can be calibrated)

disagreement with theor. due to effective peaktime

G. De Geronimo, in “Medical Imaging” by Iniewski

TM


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Direct timing

Direct timing

ToT and TtP

  • dedicated output for each channel

  • available as ToT or TtP (time-to-peak)

OM


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Amplitude measurements

Linearity

Channel uniformity

  • within 2% for ~ 1 V full swing

  • peak dispersion includes baseline

  • threshold dispersion 8.8 mV rms

  • requires improved matching and/or larger

  • trimming range (currently 15 mV)

FN


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

ART and Neighboring

Two chips (a,b) and one channel exceeding threshold (64 in chip a)

  • ART

  • threshold or peak

  • with address

flags and

readout

multiplexed sequential

peak detect outputs

  • analog pulses

  • only one exceeds threshold

  • neighbors (chan. and chip) enabled for peak detection

V2


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Plans for VMM2

trigger

neighbor

direct timing (ToT, TtP, PDAD)

logic

or

real time address (ART)

6bPDAD

timing clock

mux

CA

shaper

peak

10b ADC

mux

mux

10b ADC

time

FIFO

data (ampl., time, addr.)

6b coarse

mux

addr.

channel

count

logic

data clock

  • fixes, higher gain setting, lower gain setting (5pC)

  • external trigger

  • 6-bit peak detector and digitizer (PDAD) for direct timing

  • 10-bit 5MS/s ADCs per channel and FIFO

    • fully digital IOs, derandomization, simultaneous measurement and readout

  • 6-bit counter for coarse timing


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Conclusions

  • VMM is an ASIC family for the ATLAS Muon Spectrometer upgrade (Micromegas, TGC)

  • VMM1 has been developed and tested, with results in good agreement with the design

  • Main issues with the charge amplifier compensation (limits the rise time at large capacitance) and the large leakage from the ESD protection

  • VMM2 (in design) will integrate a number of improvements for simultaneous measurement and readout

Acknowledgment

Ken A. Johns, Sarah L. Jones (University of Arizona, USA)

Nachman Lupu (Technion Haifa, Israel)

Howard Gordon and Craig Woody (BNL, USA)

ATLAS review team (J. Oliver, M. Newcomer, R. Richter, P. Farthouat)


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Backup slides


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

Peak detection

1 - Track (< threshold)

• Analog output is tracked at hold capacitor

• MP and MN are both enabled

2 - Peak-detect (> threshold)

• Pulse is tracked and peak is held

• Only MP is enabled

• Comparator is used as peak-found

3 - Read (at peak-found)

• Amplifier re-configured as buffer

• High drive capability

• Amplifier offsets is canceled

• Enables rail-to-rail operation

• Accurate timing

• Some pile-up rejection


Gianluigi de geronimo jack fried shaorui li jessica metcalfe

ENC and timing coefficients for various shapers

G. De Geronimo, in “Medical Imaging” by Iniewski


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