Megaimpulse PPM0732 User manual

PICOSECOND
PULSE GENERATOR MODULE
PPM0732
USER MANUAL
© 2022 Megaimpulse Ltd.

Copyright © 2022 MEGAIMPULSE Ltd. All Rights Reserved.
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APPEAR IN THIS MANUAL, INCLUDING THE PRODUCTS AND SOFTWARE DESCRIBED IN IT.
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intent to inf inge.
Megaimp lse Ltd. contact information
Add ess: 26 Polytechnicheskaya st ., St. Pete sbu g, 194021 Russia
www: http://www.megaimpulse.com
e-mail: mp@powe .ioffe. ssi. u
phone/fax: [phone]

CONTENTS
Safety manual .............................................................................................. 2
Package content ........................................................................................... 3
Gene al view of picosecond pulse gene ato .................................................. 3
Desc iption of the gene ato ope ation .......................................................... 4
Technical specification ................................................................................. 7
Top, f ont and ea panels view ..................................................................... 8
Bottom view ................................................................................................. 9
Putting the gene ato into ope ation .............................................................. 10
T igge ing of the gene ato ........................................................................... 12
Wa anty ...................................................................................................... 13
PPM0732 User Manual 1

SAFETY MANUAL
Electrical safety
 PPM0732 pulse gene ato module is high voltage equipment. Please be
ve y ca eful and ope ate by qualified pe sonnel only.
 The e is a isk of elect ic shock, st ong elect omagnetic inte fe ence,
damage of the gene ato , o othe elect onic equipment in case of imp ope
use.
 It is st ongly p ohibited to switch on the gene ato without an output
coaxial cable. We ecommend using at least 50 centimete s length coaxial
cable connected between the gene ato and the load (antenna o fi st
attenuato ) to p event pe manent damage to the gene ato . The e is a isk of
elect ical a cing on the open HV coaxial connecto and damage to the
output ci cuit of the gene ato .
 When adding o emoving the gene ato to o f om the system, ensu e that
the powe supply is unplugged (in OFF state). Please apply powe supply
only afte connecting output and input coaxial cables.
 Please p ovide sufficient f ee space and allow f ee ai flow a ound the
gene ato fo good cooling in case of long time ope ation at a high
epetition ate.
Operation safety
 Please ead this manual befo e installing and using the gene ato .
 Befo e using the p oduct, make su e that all the cables a e applicable and
not damaged. High voltage connecto s should be clean and d y, f ee f om
dust, di t, and any obstacles.
 To avoid sho t ci cuits, keep metal pa ts like clips, sc ews, and staples
away f om the gene ato .
 The gene ato is designed fo ope ation in no mal labo ato y conditions.
Avoid dust, humidity, and tempe atu e ext emes. Do not place the
gene ato in any place whe e it may become wet.
 Place the gene ato on a stable su face.
 If you encounte any technical p oblem with the gene ato , please contact
Megaimpulse Ltd. Do not t y to epai the gene ato by you self.
MEGAIMPULSE LTD. 2

PACKAGE CONTENT
Please check the package fo the following items:
 PPM0732 picosecond pulse gene ato module (he einafte "gene ato ")
 Dual voltage AC/DC switching powe conve te :
AC 85V..264V, 47Hz..63Hz / DC +24V, 0.6A; DC +160V, 0.3A;
 Semi igid coaxial cable assembly N connecto /SM141 cable/open fo the
output pulses feeding and connection to the load by solde ing o optional
connecto ;
 Coaxial cable assembly SMA connecto /RG316 cable/SMA connecto
fo the input t igge ing signal feeding;
 Use manual (p inted o elect onic ve sion).
Fig.1. Gene al view of PPM0732 picosecond pulse gene ato module.
PPM0732 User Manual 3

DESCRIPTION OF THE GENERATOR OPERATION
PPM0732 gene ates picosecond ise time unipola high voltage pulses
with up to 7kV amplitude and high epetition ate. It is made as a compact pulse
gene ato module (head) with an exte nal powe supply and exte nal t igge ing.
The exte nal dual voltage DC powe supply is included in the standa d
package togethe with the fou wi es DC powe supply cable. If an alte native DC
powe supply with an optional supply cable is used, then please connect it
acco ding to the labels and contact pins desc iption. Imp ope connection may
damage the gene ato pe manently.
 The gro nd wires of the power s pply cable are marked by black
color. Low voltage and high voltage s pply wires are marked by the
labels.
The contact pins of the powe supply connecto a e the following:
Pin 1 – GND (g ound etu n DC +24V)
Pin 2 – DC +24V low voltage supply
Pin 3 – GND (g ound etu n DC +160V)
Pin 4 – DC +160V high voltage supply
The typical output pulse wavefo m is shown in Fig.2. No mally the
gene ato should ope ate on 50 Ohm matched load, fo example, UWB antenna
connected by 50 Ohm impedance coaxial cable.
Fig.2. PPM0732 typical output pulse wavefo m on matched 50 Ohm load.
MEGAIMPULSE LTD. 4 MEGAIMPULSE LTD. 4

 It is strongly prohibited to t rn on the generator witho t the load
(with the open HV connector). We recommend sing 50 centimeters
length coaxial cable between the generator and the load (antenna or
first atten ator) to prevent damage to the generator in the case of
load breakdown.
Ope ation on unmatched load inevitably esults in eflection f om the
load. Pa t of the pulse ene gy etu ns back to the gene ato and may ove heat it.
PPM0732 has ove heating p otection. If the tempe atu e exceeds 55 ºC, then the
ed LED "OVERHEAT" lights on and the t igge ing is blocked. Please cool down
the gene ato and educe the epetition ate if equi ed.
 Please provide free airflow aro nd the generator d ring long-time
operation at high freq ency, especially if the load is nmatched.
The gene ato is t igge ed by the leading edge of the exte nal t igge ing
pulse. The e is no inte nal t igge ing mode. Acceptable t igge ing pulse amplitude
is +3.5V … +5V at 50 Ohm. Low t igge ing pulse amplitude leads to unstable
t igge ing and inc eases output pulse jitte . The ecommended t igge ing pulse
width is 170 ns, while the acceptable ange is 10 ns ... 1000 ns. Pulse ise and fall
time should be no mo e than 1 ns. Longe ise/fall time may inc ease the output
pulse jitte . O ange LED "SYNC IN" lights on in the case of successful t igge ing.
The e is an integ ated Phase Locked Loop (PLL) ci cuit that cont ols the
output pulse position in time and synch onizes it with the t ailing edge of the
t igge ing pulse, if the t igge ing pulse width stays within 168 ns …175 ns.
Fig.3. PPM0732 block diag am.
The block diag am of PPM0732 is shown in Fig.3. It consists of the
cont ol system, DSRD/SAS output stage, powe MOSFETs, d ive s, as well as the
phase detecto and va iable delay ci cuit.
PPM0732 User Manual 5

Fig.4. Ope ation of PPM0732 synch onization system.
The p inciple of PPM0732 synch onization system ope ation is clea
f om the block-scheme and timing diag am (Fig.3 and Fig.4). The key components
a e the phase detecto and va iable delay ci cuit. The phase detecto compa es the
time position of the output HV pulse and the position of the t ailing edge of the
t igge ing pulse. Its output signal, which is p opo tional to the time diffe ence, is
integ ated and applied to the va iable delay ci cuit. In this way, the phase detecto
and va iable delay ci cuit wo k togethe as a PLL ci cuit and ensu e the
synch onization of the output HV pulse with the t ailing edge of the t igge ing
pulse. Usually, a few hund ed pulses a e equi ed fo the phase-locking and exact
synch onization. The t igge ing pulse width tt ig should be fixed and stay within
168 ns ... 175 ns because the phase captu e window tw is 7 ns only. The captu e
window tw is na ow, but it is enough to compensate fo the tempe atu e d ift and
aging of the components.
The efo e, the output pulse position becomes stable in time and does not
depend on the heating and aging of HV switches, IC, and passive components.
The gene ato has inte nal ove f equency p otection. If the f equency of
the t igge ing pulses exceeds the maximum value, then the gene ato blocks the
t igge ing and ed LED “OVERLOAD” lights on. The same occu s if the
t igge ing pulse is too long. Please educe the f equency of the t igge ing pulses
and/o t igge ing pulse width.
Two fans a e used fo the cooling of the gene ato . If the tempe atu e is
low, then the fans a e stopped. The otation speed of the fans inc eases with
inc easing the tempe atu e. The efo e, the cooling system stabilizes the
tempe atu e of the gene ato . This imp oves the stability of the output pulse
wavefo m and educes tempe atu e d ift.
MEGAIMPULSE LTD.

TECHNICAL SPECIFICATION 1)
Output pulse amplitude 2) 6 … 7 kV
Pulse pola ity and wavefo m Positive, fast rise, short peak,
exponential decay
Output connecto and load impedance 50 Ohm
Pulse ise time (fast pa t) < 150 ps
Pulse width (FWHM) < 400 ps
Max epetition ate (continuous) 10 kHz
Jitte (RMS) < 20 ps
Jitte (peak-to-peak) < 100 ps
Inte nal delay (f om leading edge of
the t igge ing pulse to the output pulse)
~ 170 ns
T igge ing External only
Input t igge ing pulse connecto SMA
T igge ing pulse pa amete s
+5V amplit de on 50 Ohm; width:
170 ns nominal, 168 ns … 175 ns
acceptable for PLL, 10 ns ... 1000 ns
s itable for triggering;
1ns rise/fall time
Powe supply +24V, 0.3A;+160V, 0.3A
Size 250 х 130 х 80 mm3
Ope ation tempe atu e 0 °C.. +50°C
1) All the pa amete s a e measu ed afte the ope ation of the gene ato within 10
minutes at 5 kHz epetition ate.
2) Output pulse amplitude inc eases with inc easing of the epetition ate and may
change within ±10% depending on the tempe atu e and ope ation egime.
PPM0732 User Manual 7

TOP VIEW
SIDE VIEW
LEFT AND RIGHT VIEW
1 – cont ol LED (f om top to bottom)
+24V DC (g een) – low voltage +24V DC powe supply is applied
+HV DC (g een) – high voltage +160V DC powe supply is applied
SYNC IN (o ange) – t igge ing of the gene ato
OVERHEAT ( ed) – too high tempe atu e
OVERLOAD ( ed) – too high epetition ate
2 – Input t igge ing SMA connecto
3 – Powe supply connecto
4 – 4x mounting holes 4.2 mm dia, 222x118mm footp int
5 – Output HV N-type connecto
5
4
MEGAIMPULSE LTD. 8
1
2
3

BOTTOM VIEW
The e a e five holes on the bottom which give access to the t imme s fo
the fine-tuning of PPM0732 ope ation. The holes a e closed by the hexagon socket
set sc ews. Please use the hex sc ewd ive to emove them. The gene ato has
been al eady adjusted at the facto y. The efo e, no mally the additional adjustment
is not equi ed in the End Use labo ato y. Please consult with Megaimpulse Ltd.
befo e adjusting the t imme s.
FEEDBACK – co ects the possible skew of the output pulse elative to the
t ailing edge of the t igge ing pulse at diffe ent epetition ates. The adjustment is
equi ed if the pulse position is co ect at some epetition ate (fo example at
1kHz) but shifted up to 1 ns at anothe epetition ate (fo example at 5 kHz).
INT_DELAY – adjusts the inte nal delay of the gene ato which allows to shift of
the phase captu e window and make it the same fo all the gene ato s within the
a ay.
SET_TEMP – sets the tempe atu e which the cooling system will keep stable by
changing the fans otating speed.
AMPLITUDE – adjusts the amplitude of the output pulse. Please be ca eful with
this t imme , too high set amplitude may esult in pe manent damage to the output
HV components.
WAVEFORM – adjusts the output pulse wavefo m which helps to make output
pulse mo e na ow and sha p, as well as adjusts the p epulse amplitude and pulse
width.
PPM0732 User Manual 9

PUTTING THE GENERATOR INTO OPERATION
 Please follow strictly the described steps. It helps to prevent damage to
the generator and other eq ipment.
Step 1.
Unpack the gene ato and check the p esence into the package of the following
items:
- PPM0732 pulse gene ato ;
- Dual voltage AC/DC switching powe supply conve te with the powe
supply cable;
- Semi igid coaxial cable assembly N_connecto /SM141_cable/open fo
the output pulses feeding;
- Coaxial cable assembly SMA/RG316_cable/SMA fo the input t igge ing
pulses feeding.
Step 2.
 In the case of using standa d AC/DC switching powe supply conve te :
Connect it to the gene ato and powe supply outlet.
 In the case of using alte native powe supply:
Please set the exte nal powe supplies acco ding to the ecommended low voltage
and high voltage levels befo e connecting to the gene ato . Check the powe
supply cable and connect it co ectly. The g ound wi es a e ma ked by black
colo . Low voltage and high voltage supply wi es a e ma ked by the labels.
Step 3.
Connect the output semi igid coaxial cable to the gene ato and the load.
Connect the t igge ing pulse gene ato by input coaxial cable.
Step 4.
Tu n on (plug) powe supply. Both g een LED “+24V DC” and “+HV DC” should
light on. Set the exte nal t igge ing pulses f equency to 1 kHz, pulse amplitude to
+5V, pulse width to 170 ns. Apply t igge ing pulses, o ange LED “SYNC IN”
should light on.
High voltage output pulses should be gene ated. Please check them. Set the
exte nal t igge ing pulses f equency as equi ed, but below o equal to the
maximum epetition ate.
PPG-5/1 and PPG-7/10 picosecond pulse generators user manual 9 MEGAIMPULSE LTD. 10

 Please pay attention that most of the standard GHz range coaxial
atten ators are not s itable for direct registration of o tp t p lses
beca se of extremely high peak power. Even 100W and more power
atten ators will be broken inevitably. We recommend sing of 142 series
Barth Electronics atten ator (for the freq encies below 5 kHz) as the first
atten ator connected j st to the generator o tp t or se a high voltage
directional co pler.
The gene ato is designed fo the long time ope ation at the max epetition ate.
But it can be ove heated in the case of unmatched load and high ambient
tempe atu e. Please p ovide f ee ai flow a ound the gene ato fo a good cooling.
The tempe atu e of the gene ato should be below 55 °C. Reduce the epetition
ate and/o imp ove the ai flow if ove heating occu s.
If the f equency of the t igge ing pulses is too high, then the ed LED
“OVERLOAD” lights on and the gene ato stops the ope ation. Please educe the
f equency of the t igge ing pulses, LED “OVERLOAD” lights off and the
gene ato continues the ope ation automatically.
PPM0732 User Manual 11

TRIGGERING OF THE GENERATOR
The ecommended t igge ing pulse wavefo m is shown in Fig. 5. Nominal
t igge ing pulse amplitude is +5V on 50 Ohm, pulse du ation should be within
10 ns ... 1000 ns, ise and fall time should be 1 ns o less. Longe ise/fall time
may esult in inc easing of the output pulse jitte .
Fig. 5. Recommended t igge ing pulse wavefo m.
MEGAIMPULSE LTD. 12

WARRANTY
Please see you sales ag eement to dete mine the wa anty pe iod and wa anty
te ms. The gene ato has wa anty seals.
 Removing of the warranty seals terminates the warranty.
PPM0732 User Manual 13