COL 9(suppl.), S10307(2011) CHINESE OPTICS LETTERS June 30, 2011
Study on the circuit producing high-speed pulse with high
peak current
Deke Yan (
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1,2∗
, Yongsheng Gou (
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, Zhiyuan Song (
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1,2
,
Chuandong Sun (
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)
1
, and Shaolan Zhu (
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1
1
State Key Laboratory of Transient Optics and Photonics
§
Xi’an Institute of Optics and
Precision Mechanics, Chinese Academy of Sciences
§
Xi’an 710119, China
2
Graduate University of Chinese Academy of Sciences, Beijing 100049, China
∗
Corresponding author: yandeke@opt.ac.cn
Received December 9, 2010; accepted January 25, 2011; posted online June 29, 2011
To achieve high peak current with narrow pulse width, the circuit model is analyzed based on a fast and
high-power metallic oxide semiconductor field effecttransistor (MOSFET) as the high speed switch of the
resistor-capacitor (RC) charge and discharge circuits. It is easy to obtain a narrow high-current pulse by
adopting the narrow triggering pulse to control the on-off state of the MOSFET switch, and using the
driving pulse to modulate the ex ponential decay pulse in the RC discharge loop. The procedure for the
high speed MOSFET switch is then discussed. To make the speed of the MOSFET switch as quick as
possible, the push- pull driving circuit for the grid of t he MOSFET is brought forward and the circuit
for producing the narrow trigger pulse is designed. The ex perimental result shows that the full width at
half maximum (FWHM) of the trigger pulse is about 500 ps when the narrow trigger pulse is connected
with the discharge return circuit. Measured results demonstrate that th e RC discharge loop produces a
narrow high-current pulse, with a peak current of up to 92.5 A and FWHM of 6.2 ns. After adjusting
relevant parameters, the peak cu rrent could reach up to 115.9 A. However, the corresponding pulse width
is b roadened. Finally, influencing factors on the narrow pulse width for the discharge loop are briefly
analyzed.
OCIS codes: 140.0140, 260.0260, 320.0320.
doi: 10.3788/COL201109.S10307.
In engineering, narrow high-current pulses have impor-
tant values. For example, in a semiconductor pulsed laser
ranging system, the laser must be a high peak power
pulse to achieve high pre c ision and wide-range measure-
ment. Given that the output laser pulse is directly con-
trolled by the excitation pulse, and the value of the driv-
ing current pulse determines the peak power of the laser
pulse, the incentive system must pr oduce a narr ow cur-
rent pulse.
Energy compression technology can be adopted in or-
der to obtain a narrow high-curre nt pulse. In this tech-
nology, energy is accumulated stably by storage devices
and then released quickly by the load resistance, making
it easy to obtain a narrow high-current pulse. In the dis-
charge circuit, the storage device can be both a capacitor
and an inductor.
The switch plays an importa nt role in energ y compres-
sion technology. The non-linear switch device ca n be a
thyristor, an avalanche transistor, etc. However, the peak
value of the current pulse generated using such a switch
is not high enough. With the development of high-speed,
high-power metallic oxide semiconductor field effecttran-
sistor (MOSFET) technology, using the MOSFET as a
switch to produce a pulse with high speed and high cur-
rent has become a good choice
[1−4]
. Therefore, the driv-
ing unit used for generating narrow high-current pulse is
designed based on MOSFET as a high-speed switch.
Restor-capacitor (RC) circuit discharge is the most
common energy compress ion technology being used to-
day. The simplified equivalent circuit of the RC charge-
discharge circuit using MOSFET as a switch is shown
in Fig. 1. The narrow driving pulse for the gate of
the MOSFET controls the on-off states of the MOS-
FET switch. These on-off states demonstrate the charge-
discharge states of the RC circuit, respectively. Using the
driving pulse to modulate the exponential decay pulse
in the RC discharge loop, and choosing the proper pa-
rameter values of the charging voltage and the discharge
resistance, it can be easy to obtain a narrow rectangle
high-current pulse.
Assuming the initial charge voltage is V
0
, we ignore
the role of the distribution inductance in the circuit.
Then, when the charging voltage value of the capacitor
C reaches V
0
, we turn the switch on. Combined with the
initial conditions, the circuit equation is:
I =
V
0
R
e
−
t
RC
. (1)
According to the equation, the current flowing through
the load resistance is shown as the decay exponential, and
the decay process is related to the time constant RC. The
peak current is decided by the value of the initial voltage
V
0
and load resistance R. If the value of RC is great
enough, in a very short time after the initial moment,
Fig. 1. The equivalent circuit of the RC charge-discharge
loop.
1671-7694/2011/S10307(4) S10307-1
c
2011 Chinese Optics Letters
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