Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Rectangular or pulse waveform width control
Reexamination Certificate
2001-08-08
2002-11-19
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Rectangular or pulse waveform width control
C327S173000
Reexamination Certificate
active
06483362
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-242866, filed Aug. 10, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pulse generator, particularly relates to a pulse generator for generating a pulse train having a high repeat frequency and a high duty ratio.
2. Description of the Related Art
As is generally known, it is necessary for a pulse train which is used as a driving signal for a DEMUX apparatus, a short pulse light source and a super speed finder or the like, to have a high duty ratio having a high repeat frequency in the range from several GHz to 10 GHz with a narrow pulse width in the range from 10 ps (pico second) to 15 ps (not less than 60 GHz in frequency), for example.
Under a contemporary level of technology, the highest frequency capable of being stably oscillated by an oscillator which is configured by an electric circuit, is about 40 GHz.
Accordingly, it was not possible for one pulse generator to generate a pulse train having the high duty ratio having a high repeat frequency in the range from several GHz to 10 GHz with a narrow pulse width in the range from 10 ps to 15 ps.
Therefore, a pulse generator shown in
FIG. 10A
is recommended (Jpn. Pat. Appln. KOKAI Publication No. 2000-187190).
In other words, in the pulse generator shown in
FIG. 10A
, a sine wave generator
1
outputs a sine wave signal “a” with a frequency fA in the range from several GHz to 10 GHz (a period Ta) as shown in FIG.
11
A and transmits it to a half-wave rectifier
2
.
This half wave rectifier
2
half-wave rectifies the inputted sine wave signal “a” and transmits it to a next voltage amplifier
3
as a half-wave rectified signal b having a waveform as shown in FIG.
11
B.
This voltage amplifier
3
amplifies the half-wave rectified signal b to output the half-wave rectified signal after being amplified, namely, a pulse train signal c as shown in
FIG. 11C
to an output terminal
4
.
In the pulse generator which is configured in this manner, the pulse train signal c outputted from the output terminal
4
has a repeat frequency fA (repeat period Ta) as shown in FIG.
10
B and can decrease pulse widths Tc of the respective pulses
5
composing this pulse train signal c to about ½ of the repeat period Ta.
Additionally, the pulse generator composed in this manner can decrease amount of a jitter generation of the respective pulses
5
.
Further, other pulse generator shown in
FIG. 12
is also recommended in the above document (Jpn. Pat. Appln. KOKAI Publication No. 2000-187190).
In other words, in this pulse generator shown in
FIG. 12
, for example, the sine wave generator
1
outputs the sine wave signal “a” with a frequency fA in the range from several GHz to 10 GHz (a period Ta) and transmits it to a voltage amplifier
3
a
having a movable operating point.
As shown in
FIGS. 13A and 13B
, upon amplifying the inputted sine wave signal “a”, this voltage amplifier
3
a
having a movable operating point can arbitrarily set an operation point (bias point) with respect to the inputted sine wave signal “a” by changing a signal value of a operation point control signal which is inputted from the outside.
In
FIG. 13A
, the operating point (bias point) is set at a position at 0V of the inputted sine wave signal “a”.
In this case, the amplified sine wave signal becomes a normal sine wave signal waveform in which a component in a (−) side and a component in a (+) side are substantially symmetric.
However, in this pulse generator, as shown in
FIG. 13B
, the operating point of the sine wave signal “a” is set with being moved to a negative side.
Accordingly, the sine wave signal amplified by this voltage amplifier
3
a
has a waveform shape, of which a portion of the (−) side component is clipped.
As a result, a signal waveform of the sine wave signal which is amplified by this voltage amplifier
3
a
approximates the signal waveform of the amplified half-wave rectified waveform signal c shown in
FIG. 11B
in the aforementioned pulse generator shown in FIG.
10
A.
In the case that the amplitude value (P−P) of the amplified signal is fixed, as described above, the amplified sine wave signal, namely, the respective pulses
5
of a pulse train signal c
1
to be outputted to an output terminal
4
from the voltage amplifier
3
a
have a more sharp peak waveform.
Therefore, by using the voltage amplifier
3
a
having a movable operating point, it is possible to obtain the pulse train signal c
1
having a high duty ratio with a high repeat frequency in the range from several GHz to 10 GHz and a narrow pulse width under the state that the jitter generating amount is restrained.
However, even in the pulse generators of two types as shown in
FIGS. 10A and 12A
, there are problems to be solved as follows.
At first, as shown in
FIGS. 11A
,
11
B,
11
C,
13
A and
13
B, the pulse widths Tc of the respective pulses
5
composing the pulse train signals c and c
1
to be outputted from these pulse generators are substantially determined in response to the repeat frequency Ta of the sine wave signal “a”, so that this involves a problem that it is not possible to set the pulse widths Tc of the respective pulses
5
to an arbitrary value.
Further, the pulse widths Tc of the respective pulses
5
are limited to about ½ of the repeat period Ta of the sine wave signal “a”, so that this involves a problem that it is not possible to obtain the high duty ratio in the pulse train signals c and c
1
.
Further, the pulse widths Tc of the respective pulses
5
in the pulse train signals c and c
1
are limited to the frequency properties of the amplifiers
3
and
3
a.
In other words, in order to amplify the sine wave signal “a” which is outputted from the sine wave generator
1
, it is needed to have a higher frequency property than a frequency component of the frequency fA on this sine wave signal “a”.
However, the highest frequency of the frequency properties of the amplifiers
3
and
3
a
are about 40 GHz similar to the sine wave generator
1
.
Accordingly, for example, this involves a problem that it is not easy to obtain the extremely high duty ratio such that, for example, the pulse width of the pulse
5
is in the range from 10 ps to 15 ps or the like.
Additionally, the pulse train signals c and c
1
which occur resulting from the difference of the frequency properties in the respective amplifiers
3
and
3
a
involve a problem that scattering occurs between the pulse generators each other.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made by taking the above problems into consideration, and it is an object of the present invention to provide a pulse generator of a simple structure capable of generating a pulse train having a high repeat frequency and a high duty ratio by making a pair of pulse trains, of which polarities are different each other, from one electric signal in a sine waveform and regulating the phase difference between these pulse trains each other.
(1) In order to attain the above object, the present invention provides a pulse generator comprising: signal generating means (
11
) for generating an electric signal in a sine waveform;
first pulse train generating means (
12
,
19
,
22
,
24
) for generating a first pulse train having a positive polarity corresponding to the positive polarity element among a positive polarity element and a negative polarity element which configure the electric signal in the sine waveform outputted from the signal generating means;
second pulse train generating means (
13
,
20
,
22
,
23
,
24
) for generating a second pulse train having a negative polarity corresponding to the negative polarity element among a positive polarity element and a negative polarity element which configure the electric signal in the sine waveform outputted from the signal generating means;
phase difference se
Otani Akihito
Otsubo Toshinobu
Anritsu Corporation
Cox Cassandra
Wells Kenneth B.
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