Electric power conversion systems – Current conversion – With voltage multiplication means
Reexamination Certificate
1999-11-30
2001-03-13
Wong, Peter S. (Department: 2838)
Electric power conversion systems
Current conversion
With voltage multiplication means
C363S059000, C307S110000
Reexamination Certificate
active
06201718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a step-up power supply circuit for producing a higher step-up voltage than a preselected power supply voltage, and also to an integrated circuit device equipped with the step-up power supply circuit.
2. Description of the Related Art
Conventionally, in an electronic appliance with employment of a dry cell and an on-vehicle battery, having relatively low output voltages, a step-up power supply circuit is provided. The step-up power supply circuit produces a step-up voltage in response to the output voltage of the above-described power supply. This step-up voltage is used as an operating power supply voltage in this electronic appliance.
FIG. 8
represents an example of an electronic appliance arranged by employing the above-described conventional step-up power supply circuit
1
and a semiconductor integrated circuit device
2
having a plurality of amplifiers AM
0
to AM
3
. In this drawing, the step-up power supply circuit
1
is equipped with a rectangular wave generating circuit
4
and a step-up circuit
5
, which are operated under a power supply voltage Vcc outputted from a power supply
3
such as a dry cell and an on-vehicle battery.
The rectangular wave generating circuit
4
is constituted by an astable multivibrator and the like, which outputs such a rectangular wave Sc. The amplitude of this rectangular wave is rapidly inverted in a predetermined time period. The step-up circuit
5
is arranged by a voltage doubler rectifying circuit equipped with a rectifying diode and a capacitor. The step-up circuit
5
ON/OFF-controls the rectifying diode in synchronism with the rectangular wave Sc to charge the capacitor, so that a step-up voltage HVcc higher than the power supply voltage Vcc is produced.
This step-up voltage HVcc is applied to the semiconductor integrated circuit device
2
, and since the amplifiers AM
0
to AM
3
are operated while using the step-up voltage HVcc as the operating power supply voltage, these amplifiers AM
0
to AM
3
amplify signals entered into input terminals IN
0
to IN
3
to thereby output the amplified signals to the respective output terminals Q
0
to Q
3
.
As previously explained, in the electronic appliance, the step-up power supply circuit
1
for producing the higher step-up voltage HVcc than the power supply voltage Vcc of the power supply
3
, and the amplifiers AM
0
to AM
3
are operated under the operating power supply voltage HVcc, so that the dynamic range may be extended.
On the other hand, in the above-described conventional step-up power supply circuit
1
, since the rectifying diode contained in the step-up circuit
5
is ON/OFF-controlled based upon the rectangular wave Sc containing the radio frequency (high frequency) components, the RF (radio frequency) switching noise is produced from the rectifying diode. There is a problem that this RF switching noise is entered into the amplifiers AM
0
to AM
3
provided in the semiconductor integrated circuit device
2
and then is mixed with the respective amplified signals derived from the output terminals Q
0
to Q
3
.
As the conventional problem avoiding means, the step-up power supply circuit
1
and the semiconductor integrated circuit device
2
are separately mounted on the electric circuit board. Also, the ground GND
1
of the step-up power supply circuit
1
and the ground GND
2
of the semiconductor integrated circuit device
2
are formed on the electric circuit board in such a manner that these grounds GND
1
and GND
2
are separated from each other. Furthermore, the capacitors, resistors, coils and the like capable of absorbing the above-described RF switching noise are mounted on the electric circuit board.
However, there is another problem that since such a problem avoiding means is conducted, a total number of electronic components is increased and the entire electric circuit board becomes bulky. Also, both the step-up power supply circuit
1
and the semiconductor integrated circuit device
2
are separately arranged in order to prevent the adverse influence caused by the above-explained switching noise. As a result, while the total quantity of electronic components are increased, the high-performance electronic appliance can be hardly realized within a limited volume in high density.
SUMMARY OF THE INVENTION
The present invention has been made to solve the conventional problems, and therefore, has an object to provide a step-up power supply circuit capable of suppressing an occurrence of noise, and also to provide an integrated circuit device containing this step-up power supply circuit.
To achieve the above-described object, according to the present invention, there is provided a step-up power supply circuit comprising:
a first rectifying element to which a predetermined voltage is applied from a power supply;
a first capacitive element connected in series with the first rectifying element;
a second rectifying element connected to a joint point between the first rectifying element and the first capacitive element;
a second capacitive element connected in series with the second rectifying element; and
drive means connected in series with the first capacitive element, for applying to the first capacitive element, a signal having a waveform whose amplitude is not rapidly changed, but becomes constant every predetermined time period;
wherein a step-up voltage higher than the predetermined voltage is produced from the second capacitive element by turning ON/OFF the first and second rectifying elements in response to a change in the amplitudes of the signal.
Also, a trapezoidal waveform signal is applied to the above-explained first capacitive element.
In accordance with this arrangement, when the signal derived from the drive means is applied to the first capacitive element, biases of the first and second rectifying elements are alternately inverted in response to a change in amplitudes of this signal, so that the ON/OFF switching operation is carried out. Since such an ON/OFF switching operation is carried out, a voltage substantially equal to the power supply voltage is produced across the first capacitive element, and another voltage approximately two times higher than the power supply voltage is produced across the second capacitive element. In this case, since the signal applied to the first capacitive element is such a signal having a waveform whose amplitude becomes constant every time a preselected time period has passed, but having no rapidly changed amplitudes, this signal corresponds to a signal not having a so-called “RF (radio frequency) component.” In response to the amplitude change of this signal, when the first and second rectifying elements are turned ON/OFF, the RF switching noise is not produced from these first and second rectifying elements, but the step-up power supply circuit capable of suppressing the occurrence of the RF switching noise can be realized.
According to another aspect of the invention, there is provided an integrated circuit device equipped with a step-up power supply circuit, such an integrated circuit device equipped with a step-up power supply circuit, in which the step-up power supply circuit and a circuit operated by using a step-up voltage produced from the step-up power supply circuit as an operating power supply voltage are formed on the same semiconductor substrate, said step-up power supply circuit comprising:
a first rectifying element to which a predetermined voltage is applied from a power supply and a first capacitive element is series-connected;
a second rectifying element which is connected to a joint point between the first rectifying element and the first capacitive element, and to which a second capacitive element is series-connected;
a second capacitive element connected in series with the second rectifying element; and
drive means connected in series with the first capacitive element, for applying to the first capacitive element, a signal having a waveform whose amplitude is not rapidly changed, but becomes constant e
Inohana Haruyuki
Ozawa Akio
Yoshizumi Norio
Pioneer Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Vu Bao Q.
Wong Peter S.
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