MTM-16(Data sheet V2.3_01)

Multiplexed high quality
readout for large numbers ofchannels for charged particle
detectors

More and more experiments in nuclear and particle physics require detectors with higher position
resolution and increased size. This means that more amplifier channels, filter stages and ADCs
providing high signal quality are needed at lower cost per channel. The most effective approach toreduce costs is early multiplexing within a front end electronics which is situated near the detector.
From analog signal processing requirements, the earliest stage for time multiplexing is directly
behind the shaping amplifiers.
One method of time multiplexing is to store
the individual amplitudes as a charge in acapacitor, switch it to a bus line one channel
after the other and digitize it with an ADC ina CAMAC or VME module. Several 100
channels can be digitized this way with aminimum of cabling and only one ADC. Many
approaches have been made with monolithic
integrated circuits, but for many applications
the signal quality (amplitude resolution,
linearity, offset, offset drift, low noise at highinput capacity) and the flexibility (missingfeatures like: good timing, self triggering or
adapted energy range) are not sufficient. Also
the available digitizers will not provide highresolution with low differential non linearity(sliding scale ADCs) which is necessary forspectroscopy applications.

The implemented preamplifiers should be low
power for vacuum operation and a specialversion should be suitable also for highcapacity detectors up to 2 nF (typical forlarge and thin energy loss detectors). It will
provide excellent timing and some types willallows to create multiplicity selective triggers.

mesytec GmbH & Co. KG
Wernher-von-Braun-Str.1, D-85640 Putzbrunn, Germany
phone: +49 -89 / 456007-30 fax: +49 -89 / 456007-39
info@mesytec.com – www.mesytec.com

MTM-16

Multiplexed high quality readout

16 channel front end electronics
It includes charge sensitive preamplifiers, variable gain and polarity stage, a timing branch with filter
amplifier and discriminators, and a slow branch with spectroscopy amplifiers followed by a track & holdstage. Up to 16 MTM-16 (= 256 channels) can be connected to one readout bus, allowing to reduce cablingand hardware costs. All parameters can be set and controlled via integrated slow bus, allowing easy operationof the units in vacuum or enclosed environments.

Common settings for all channels
Preamp gain, polarity

preceeding module to determine its time slot for
sending the amplitude information.

(via control bus or coder)

Detector bias supply

Discriminator threshold

Lemo input, maximum ±400 V. Provides highvoltage to the detector. AC-coupling and filteringof the bias voltage is provided.
For SHC type max ±40 V is allowed.

(Potentiometer / control bus)

Digital multiplexer output signals
CHS signal

Pulser input

includes “hold“ and “slow bus“ as positive pulse,“clk“ as negative pulse.

Lemo input, tail pulse required.
Type 100/500 MeV
LP: 110 MeV/V

hold for a l us shaping time the hold signal mustgo active 2 us after the timing trigger output. It is
reseted automatically after readout.
control bus is a bidirectional bus, which allows to
set thresholds, gains, polarity, modes and also to
get information from the MTM-16. It can behandled directly via MDI-2 with VME commands.
clock is a 50 ns negative signal. It is used as atime base for shifting out the analog amplitudes
from the hold stages. Each module must have aunique address given by a coder on the board.

Type 7/35 MeV

LP: 15 MeV/V

Type 5/25 MeV

HC/SHC: 15 MeV/V

Power(supplied via MDI-2) (+12 V / +5 V / –5 V)
Type 100/500 MeV LP:(40 mA / 110 mA / –30 mA)
Total Power: 1.2 W
Type 20/100 MeV LP:(40 mA / 110 mA / –30 mA)

MTA signal

Total Power: 1.2 Wincludes a negative trigger signal fromdiscriminators (optional also multiplicity) and theamplitude signal with synchronisation marks.

Type 7/35 MeV LP:(40 mA / 110 mA / –30 mA)
Total Power: 1.2 W

trigger signal

If hold or readout is not active all MTM-16 canadd digital trigger pulses to the line.
They are converted to a trigger signal by theMDI-2 module.

Type 5/25 MeV HC:(60 mA / 140 mA / –20 mA)
Total Power: 1.5 W
Type 5/25 MeV SHC:

amplitude signal (max ±1.3 V)

For sequential mode (standard) the multiplexer
unit waits for the MTA-module ready marks of themesytec GmbH & Co. KG
Wernher-von-Braun-Str.1, D-85640 Putzbrunn, Germany
phone: +49 -89 / 456007-30 fax: +49 -89 / 456007-39
info@mesytec.com – www.mesytec.com(140 mA / 140 mA / –20 mA)
Total Power: 2.5 W

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Multiplexed high quality readout

Functional units of MTM-16
Gain/polarity stage

Serial mode

allows to add an amplification of 5 and to adapt toinput signal polarity. Related coder settings are:(useful if many channels respond simultaneously,
no threshold or self trigger needed)
Readout time with 10 MHz clock: 1700 ns per
MTM-16 in the chain.
example:128 channels = 8x MTM-16 → 15.8 us readout
time from trigger to ready for new trigger.

0: gain = 1, input polarity = pos
1: gain = 5, input polarity = pos
E: gain = 1, input polarity = neg
F: gain = 5, input polarity = neg
Gain/Polarity can also be set via remote control.
Shaper

A shaping time of 1 us (2.3 us FWHM) .
CR (RC)3 gaussean shaper.
Stretcher stage

holds the actual shaper signal at the maximum
within the gate signal created by MDI-2.
TF

A timing filter amplifier: differentiation andintegration to filter the fast timing signals.
Discriminator

Overheat shutdown

not implemented in the current revision.
Cooling under vacuum conditions

For not too densely packed low power devices(100 pF type) in vacuum and for operation outside
vacuum, cooling is not necessary. The high powerdevices (for high detector capacity) can beoperated in vacuum without cooling if theirdistance is more than 100 mm. For densely
packed devices in vacuum a liquid cooling isnecessary. It can be designed in collaboration withthe customer.

Fast discriminator with variable threshold for sub
nanosecond timing. 4 timing signals ofneighbouring channels are added and thendiscriminated. The threshold can be adjusted bytrim potentiometer and can be measured at thesense point. 2V corresponds to single channel
maximum range. Threshold can also be controlled
via remote control (RC).

Size of the units

OrSequencing

Makes a logical or from the 4 timing signals forcommon timing output.

17 clocks needed per module. Set MDI-2 register“seq0_cct_ seq1_cct”
The maximum clock frequency of 10 MHz isallowed. (reg seq_clk_freq0/1 = 3)

Multiplexer

readout time estimates(trigger to readout start is about 2 us):For LP-devices: further reduction to 0.95 W
will be possible in next revision
Clock frequency

Max 10 MHz(at 10 MHz 2.5 % of crosstalk to the following
channel in the readout chain has to be expected:
channel 0 → 8 , 1 → 9 ....)For lower readout frequencies crosstalk isnegligible.

16 channel unit: 100 x 160 x 6 mm³
Setting the gate

Parameters which have to be written into theMDI2 module are:• hold_delay0/1 = 1000
• hold_width0/1 = 34

Data output format

Data wich are found in the MDI-Buffer areinterlaces. This means:
event 0 represents channel 0
event 1 represents channel 8
event 2 represents channel 1
event 3 represents channel 9 ….

mesytec GmbH & Co. KG
Wernher-von-Braun-Str.1, D-85640 Putzbrunn, Germany
phone: +49 -89 / 456007-30 fax: +49 -89 / 456007-39
info@mesytec.com – www.mesytec.com

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MTM-16Multiplexed high quality readout

Remote Control via MDI-2 and VME
MTM-16 commands: (the MTM-16 can be initialised with 2 write commands)
The MDI-2 allows to send the format: busnumber, id, opcode, address, data
Data at Address 0432

10

Set rc-status
1 = setrc_status(1 = on)not usedpolarity
0 = neg. input
1 = pos input

gain
0 = high gain
1 = low gain

Data at Address 1

set common thresholddat[11:0] → dac (0xfff = 50 % of single channel range)
The data are immediately read back from the module and can be checked at register 0x6086 and 0x6088.
Explicit reading with opcode 18 is not supported for present MTM-16.
Send time is 400 us. Wait that fixed time before reading response or sending new data.
Also polling at 0x608A for bit 0 is possible. For details see MDI-2 data sheet.
Input connector• Input connector(s). SubD 25 female connector (for a 16 channel unit)• Pin assignment:
Functionconnector

Funktionconnector

Sig-gnd1, 2, 7, 12, 13, 14, 15, 25

Cha 819

Cha 011

Cha 96

Cha 1

23

Cha 1018Cha 210

Cha 115

Cha 322

Cha 1217

Cha 4

9

Cha 134

Cha 521

Cha 1416

Cha 68Cha 153Cha 7

20guardring

24The guardring output (24) is connected via R-C-R filter (100 kΩ, 10 nF, 100 kΩ)to the common detector bias input.

mesytec GmbH & Co. KG
Wernher-von-Braun-Str.1, D-85640 Putzbrunn, Germany
phone: +49 -89 / 456007-30 fax: +49 -89 / 456007-39
info@mesytec.com – www.mesytec.com

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MTM-16

Multiplexed high quality readout

MTM-16 PCB overview

mesytec GmbH & Co. KG
Wernher-von-Braun-Str.1, D-85640 Putzbrunn, Germany
phone: +49 -89 / 456007-30 fax: +49 -89 / 456007-39
info@mesytec.com – www.mesytec.com

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MTM-16

Multiplexed high quality readout

Set ID

The MTMs on a bus must have unique IDs in consecutive order, starting with ID 0.
So for one MTM-16 on the bus the ID has to be 0.
Set gain / polarity

0: gain = 1, polarity = pos
1: gain = 5, polarity = pos
E: gain = 1, polarity = neg
F: gain = 5, polarity = neg
Set thresholdA single channel has a maximum amplitude of 2 V per channel.
The threshold is applied to the sum signal of four neighbouring channels.
(0 to 3 / 4 to 7 / 8 to 11 / 12 to 15).
Power Coderhas only a function on high power devices. When jumpered the power consumption is reduced andpreamplifier noise is increased.
Main GND

for multi MTM-16 setups, the PCBs have to be connected very well with this ground connection.
Bias supply

Input for detector bias. A T-filter is implemented with a common 1MΩ bias input resistor followed by a10 nF filter capacitor.
The filtered bias is distributed by 16 individual 10 MΩ resistor to the preamplifier inputs.
Pulser input

expects a tail pulse with fast rise time (typ 10...20 ns) and slow decay time (typ 100 us).
All channels respond simultaneously.

mesytec GmbH & Co. KG
Wernher-von-Braun-Str.1, D-85640 Putzbrunn, Germany
phone: +49 -89 / 456007-30 fax: +49 -89 / 456007-39
info@mesytec.com – www.mesytec.com

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