Electric power conversion systems – Current conversion – Using semiconductor-type converter
Reexamination Certificate
2000-08-09
2001-08-14
Patel, Rajnikant B. (Department: 2838)
Electric power conversion systems
Current conversion
Using semiconductor-type converter
C323S315000, C330S261000
Reexamination Certificate
active
06275402
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a precision fullwave rectifier which is used in communication systems or non-linear signal processors.
2. Discussion of Related Art
FIG. 1
shows a circuit for a precision fullwave rectifier using operational amplifiers according to a related art.
Referring to
FIG. 1
, a precision fullwave rectifeir
10
of a related art amplifies an alternating current input voltage Vin by operational amplifiers and rectifies the current by diodes.
More specifically, a negative input terminal of a first operational amplifier AMP
1
receives an input voltage through a first resistor R
1
while a positive input terminal is connected to the ground through a sixth resistor R
6
.
A first diode D
1
is connected backward between an output stage and the negative input terminal of the first operational amplifier AMP
1
, while a second diode D
2
is connected forward between the output stage and the negative input terminal.
An output of the first operational amplifier AMP
1
is connected to a negative input terminal of a second operational amplifier AMP
2
from a node between a second resistor R
2
and the first diode D
1
through a third resistor R
3
, and a wave-rectified output is outputted from an output terminal of the second operational amplifier AMP
2
. An alternating current input voltage Vin is connected to a negative input terminal of the second operational amplifier AMP
2
through a fourth resistor R
4
, while a positive input terminal of the second operational amplifier AMP
2
is connected to the ground through a seventh resistor R
7
. Besides, a fifth resistor R
5
is connected between the output stage and the negative input terminal of the second operational amplifier AMP
2
.
The first, third, and fourth resistors R
1
, R
3
, and R
4
are equal to one another in resistance, while the resistance of the second resistor R
2
is twice larger than that of the first, third or fourth resistor R
1
, R
2
or R
4
.
The precision fullwave rectifier of the related art is operated as following.
When the alternating current input voltage Vin is a positive pulse(i.e., the voltage has a positive value), the first diode D
1
is turned ‘on’ while the second diode D
2
is turned ‘off’.
Vamp
1
=−Vin·(R
2
/R
1
) (formula 1-1)
In the above formula 1-1, an output of the first operational amplifier AMP
1
is an inverted negative pulse(i.e, a negative value) having a predetermined gain(Av=R
2
/R
1
)
Vamp
1
+Vin=−Vin·(R
2
/R
1
−1) (formula 1-2)
The output of the first operational amplifier AMP
1
as well as the positive pulse of the initial alternating current input voltage Vin is inputted to the negative input terminal of the second operational amplifier AMP
2
.
Namely, an output Vout of the second operational amplifier AMP
2
is inverted to be outputted as a positive pulse, which is shown in the following formula.
Vout
=
-
(
Vamp1
+
Vin
)
·
(
R5
/
R3
)
=
-
[
-
Vin
·
(
R2
/
R1
-
1
)
]
·
(
R5
/
R3
)
=
+
[
Vin
·
(
2
-
1
)
]
·
(
R5
/
R3
)
=
Vin
·
(
R5
/
R3
)
(formula 1-3)
When the alternating current input voltage Vin is a negative pulse(i.e., a negative value), the first diode D
1
is turned ‘off’ while the second diode D
2
is turned ‘on’.
Vamp
1
=−Vin·(
0
/R
1
) (formula 1-4)
Accordingly, an output of the first operational amplifier AMP
1
, as shown in formula 2-1, is connected virtually to the negative input terminal, becoming 0.
Moreover, a negative pulse of the alternating current input voltage Vin is inputted to the negative input terminal of the second operational amplifier AMP
2
.
In this case, the output Vout of the second operational amplifier AMP
2
is as following.
Vout=−Vin·(R
5
/R
4
) (formula 1-5)
Namely, the negative pulse is inverted to be outputted as a positive pulse, thereby operating wave rectification of the alternating current input voltage.
Unfortunately, the precision fullwave rectifier using operational amplifiers of the related art requires a plurality of resistors consisting of a plurality of pairs, two operational amplifiers, and two diodes, which is unable or impossible to be embodied on an integrated circuit. Moreover, the rectifier of the related art consumes too much power, occupies a large layout area, and has an operational speed limited by the operational amplifiers.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a precision fullwave rectifier that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
The object of the present invention is to provide a precision fullwave rectifier which has a simple constitution of its circuit, is easily embodied on an integrated circuit, has no speed limitation owing to no-feedback structure, occupies a small layout area because of less devices, and needs less power consumption.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention used in communication systems and non-linear signal processors includes an input part receiving a first alternating current input signal and a second alternating current input between which a phase difference of about 180° exists wherein the input part generates a first current and a fourth current proportional to the first alternating current input signal and also generates a second current and a third current proportional to the second alternating current input signal, a first current subtractor outputting a fifth current by subtracting the second current from the first current, a second current subtractor outputting a sixth current by subtracting the fourth current from the third current, and an output part transforming and generate an wave-rectified output voltage by adding the fifth current to the sixth current. Besides, the input part further includes four NMOS transistors, each of the two current subtractors has four NMOS transistors, and the output part consists of a resistor.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
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patent: 4675594 (1987-06-01), Reinke
patent: 4717869 (1988-01-01), Koch et al.
patent: 4835487 (1989-05-01), Doyyle et al.
patent: 4941080 (1990-07-01), Sieborger
patent: 4994730 (1991-02-01), Rossi et al.
patent: 5012133 (1991-04-01), Hughes
Hyundai Electronics Industries Co,. Ltd.
Patel Rajnikant B.
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