JP2804408B2 - High voltage generation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high voltage generating circuit for generating a high voltage for obtaining an internal multiplication effect of an avalanche photodiode used as a light receiving element in, for example, an optical communication system.

[0002]

2. Description of the Related Art In recent years, in the field of communications, communication systems using light as a transmission medium have been actively developed with the demand for higher transmission speeds and wider transmission bands.

In this optical communication system, a light receiving element for converting a received signal from an optical signal to an electric signal and a light emitting element for converting a transmitted signal from an electric signal to an optical signal are required.

At present, various types of light receiving elements are considered, and one of them is an avalanche photodiode (hereinafter, referred to as “APD”).

[0005] This APD requires an internal multiplication effect
Requires high voltage. Therefore, AP as a light receiving element
When D is used, it is necessary to provide a high voltage generating circuit in the receiving circuit.

As such a high voltage generating circuit, a circuit utilizing a boosting function of a transformer has been used.

However, in such a configuration, the transformer is difficult to miniaturize and is not suitable for surface mounting.
The circuit could not be reduced in size.

Therefore, a high voltage generating circuit that does not use a transformer has been conventionally considered. An example of such a high voltage generating circuit is a circuit described in Japanese Patent Application No. 63-008381.

The high voltage generating circuit described in this document is:
A high voltage is obtained by combining a pulse oscillation circuit, a DC blocking capacitor, and a Cockcroft-Walton circuit for step-up rectification.

According to such a configuration, a high voltage can be obtained according to the amplitude of the pulse signal output from the pulse oscillation circuit and the number of boost rectification stages of the Cockcroft-Walton circuit.

Further, since the same DC blocking function and boosting function as those of the transformer can be obtained by the capacitor and the Cockcroft-Walton circuit which can be made smaller than the transformer, the circuit can be made smaller than when a transformer is used.

[0012]

However, in the above-described high-voltage generating circuit, since the amplitude of the pulse signal output from the pulse oscillation circuit is small, unless the number of boosting rectification stages of the Cockcroft-Walton circuit is increased, a desired level is obtained. There was a problem that a high voltage could not be obtained. As a result, there is a problem that it is difficult to reduce the size of the circuit to a required size even in the high voltage generation circuit.

Therefore, the present invention provides a high-voltage generating circuit that can greatly reduce the size of a circuit by making it possible to increase the amplitude of a pulse signal by adding a small amount of a circuit. The purpose is to:

[0014]

In order to achieve the above object, the present invention provides a circuit part operating at a predetermined DC voltage.
A circuit part that requires a high voltage higher than this predetermined DC voltage
A high voltage for generating said high voltage applied to a circuit having
The generator has a predetermined frequency and different polarity
Pulse signal generating means for generating a pair of pulse signals;
By the DC blocking function of the quantitative component, the pulse signal generation
DC components of a pair of pulse signals output from the stage
DC component removing means for removing the component, and a DC component removing means.
The pair of pulse signals from which the DC component has been removed
Cockcroft-Walton circuit configuration pair of inputs
Input to the terminals to boost and rectify a pair of pulse signals.
To obtain the high voltage, and
One of the pulse signal input terminals is grounded via a resistor.
Boosting rectifier means, and boosts the predetermined DC voltage
Thereby increasing the power supply voltage of the pulse generation means.
Means .

[0015]

According to the above arrangement, for example, if the step-up ratio of the step-up means is set to twice, the amplitude of the pulse signal can be set to twice the conventional value. As a result, the number of boosting rectification stages of the boosting rectification means can be reduced to less than half of the conventional case. As a result, the number of boost rectification stages can be significantly reduced by adding a small number of circuits, so that the size of the circuit can be reduced.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a configuration of one embodiment of the present invention. In the following description, the present invention will be referred to as A
A case where the present invention is applied to a high voltage generating circuit that generates a high voltage for internal multiplication of a PD will be described as a representative.

In FIG. 1, reference numeral 11 denotes a pulse oscillation circuit for generating a pulse signal to be subjected to a step-up rectification process. The pulse oscillation circuit 11 is configured to output two pulse signals P1 and P2 having different polarities as shown in FIG.

Reference numerals 12 and 13 respectively denote a pulse oscillation circuit 1
This is a capacitor that removes a DC component from the pulse signals P1 and P2 output from 1. 14 is a capacitor 12,
13, the pulse signals P1 and P2 from which the DC component has been removed.
Is a Cockcroft-Walton circuit that boosts and rectifies the voltage.

Reference numeral 15 denotes a low-pass filter for removing a ripple component from the boosted rectified output of the Cockcroft-Walton circuit 14. The output of the low-pass filter 15 is supplied to the APD 17 as a high voltage for internal multiplication.

A booster circuit 16 generates a power supply voltage of the pulse oscillation circuit 11 by boosting a power supply voltage Vcc of a receiving circuit (not shown) having the APD 17. The booster circuit 16 is configured to generate two positive and negative boosted voltages ± NVcc. Here, N is a boost factor.

The pulse oscillation circuit 11 is, for example, a CM
Six inverter circuits 11 constituted by OS gates
1-116, a capacitor 117, and resistors 118, 11
9.

Here, the inverter circuits 111, 112,
113, a capacitor 117, and resistors 118, 119
Constitutes the oscillation circuit body. In this case, the oscillation frequency is a value proportional to a time constant determined by the product of the resistance value of the resistor 18 and the capacitance value of the capacitor 17.

The inverter circuit 114 is the inverter circuit 1
13 is connected in parallel with the circuit 13 to invert the output of the inverter circuit 112 and amplify the current. This amplified output is used as the pulse signal P1.

The inverter circuits 115 and 116 are connected in parallel, and are configured to invert the output of the inverter circuit 111 located before the inverter circuit 112 and amplify the current. Thus, a pulse signal P2 having a phase opposite to that of the pulse signal P1 is obtained.

The Cockcroft-Walton circuit 14
Is composed of a plurality of boost rectification stages. Although not described in detail, each step-up rectification stage is composed of a pair of diodes that are turned on alternately according to the polarities of the pulse signals P1 and P2, and a capacitor that charges a current flowing through the diodes. In the Cockcroft-Walton circuit 14, an input terminal to which the pulse signal P2 is supplied is grounded via a resistor 141.

The positive boosted voltage + NVcc output from the booster circuit 16 is supplied to the drain electrodes of the inverter circuits 111 to 116 of the pulse oscillation circuit 11 as a drain voltage VDD. On the other hand, the negative boosted voltage −NVcc is applied to the source electrodes of the inverter circuits 111 to 116 by the source voltage Vss.
Supplied as It should be noted that, for simplification of the drawing, only a state where the boosted voltage ± NVcc is supplied to the inverter circuit 111 is shown.

The boosting factor N of the booster circuit 16 is set so as to satisfy the following equation, where VM is the maximum rated voltage of the power supply voltage of the inverter circuits 111 to 116.

| + NVcc | + | −NVcc | <VM For example, when the inverter circuits 111 to 116 are composed of 4000 series CMOS gates, the maximum rated voltage VM of the inverter circuits 111 to 116 is 18V.
On the other hand, the power supply voltage Vcc of the receiving circuit is usually 5V.
Therefore, in this case, the boost factor N is set to less than 1.8.

The operation of the above configuration will be described.

The pulse signal P 1 output from the pulse oscillation circuit 11 is supplied to a Cockcroft-Walton circuit 14 after a DC component is removed by a capacitor 12. Similarly, the pulse signal P2 output from the pulse oscillation circuit 11 is supplied to the Cockcroft-Walton circuit 14 after the DC component is removed by the capacitor 12.

The pulse signals P1 and P2 supplied to the Cockcroft-Walton circuit 14 are boosted and rectified by the Cockcroft-Walton circuit 14. Thereby, a high DC voltage is obtained.

The high voltage is supplied to the APD 17 after the ripple component is removed by the low pass filter 15. As a result, an internal multiplication action of the APD 17 is caused, and the received signal is converted from an optical signal to an electric signal.

According to this embodiment described in detail above, the following effects can be obtained.

(1) First, in this embodiment, the amplitude of the pulse signals P1 and P2 can be greatly increased by adding only a few circuits. As a result, the number of boost rectification stages of the Cockcroft-Walton circuit 14 can be significantly reduced, and the high-voltage generation circuit can be made smaller than before.

That is, conventionally, the power supply voltage V
cc was the power supply voltage of the pulse oscillation circuit. However, in such a configuration, since the power supply voltage Vcc is as low as about 5 V as described above, only a pulse signal having a small amplitude can be obtained.

On the other hand, in this embodiment, the power supply voltage V
The power supply voltage of the pulse oscillation circuit 11 is obtained by boosting cc. Thus, in this embodiment, large amplitude pulse signals P1 and P2 can be obtained.

Furthermore, the area occupied by the booster circuit 14 is smaller than the area occupied by the booster rectification stage which is reduced by increasing the amplitude of the pulse signals P1 and P2. Therefore, in this embodiment, the size of the circuit can be reduced as compared with the related art.

(2) Further, in this embodiment, the Cockcroft and the pulse signals are generated by two pulse signals P1 and P2 having different polarities.
Since the Walton circuit 14 is driven, the size of the high-voltage generating circuit can be reduced from this point as well.

That is, conventionally, the Cockcroft-Walton circuit is driven by one pulse signal. However, with such a configuration, only a high voltage corresponding to the amplitude of one pulse signal can be obtained.

On the other hand, in this embodiment, a high voltage corresponding to the sum of the amplitudes of the two pulse signals P1 and P2 can be obtained. Therefore, even if the amplitude of each of the pulse signals P1 and P2 is the same as the amplitude of the conventional pulse signal, the same high voltage can be obtained with half the number of boost rectification stages as the conventional one.

Moreover, pulse signals P1, P having different polarities
2 can be extracted by changing the extraction position even with the same pulse oscillation circuit as in the prior art. As a result, the number of boosting rectification stages can be reduced to half or less of the conventional configuration with the same pulse generation configuration as the conventional configuration, so that the circuit size can be reduced as compared with the conventional configuration.

(3) Further, in this embodiment, the pulse oscillation circuit 11 is provided with the function of amplifying the current of the pulse signals P1 and P2, so that the Cockcroft-Walton circuit 14 is driven by the pulse signals P1 and P2. In this case, it can be driven efficiently.

As described above, one embodiment of the present invention has been described in detail, but the present invention is not limited to such an embodiment.

[0045]

(1) In the above embodiment, the case where the power supply voltage of the pulse oscillation circuit is obtained from the power supply voltage of the reception circuit has been described. However, the present invention can also be applied to the case where the power supply voltage of a circuit other than the receiving circuit, or the power supply voltage of the pulse oscillation circuit is generated from a DC voltage other than the power supply voltage.

(2) In the above embodiment, a case was described in which the present invention was applied to a high voltage generating circuit that generates a high voltage for internal multiplication of an APD. However, the present invention can be applied to a high voltage generation circuit other than such a high voltage generation circuit.

(3) In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the scope of the invention.

[0049]

As described in detail above, according to the present invention,
Since the amplitude of the pulse signal can be increased simply by adding a small circuit, the size of the high-voltage generating circuit can be significantly reduced as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of one embodiment of the present invention.

FIG. 2 is a signal waveform diagram showing a pulse signal of one embodiment.

[Explanation of symbols]

11 ... pulse oscillator, 12, 13 ... capacitor, 14 ...
Cockcroft-Walton circuit, 15: low-pass filter, 16: booster circuit, 17: APD.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/26 10/28

Claims (2)

(57) [Claims] 1. A circuit part which operates at a predetermined DC voltage.
Circuit parts that require a high voltage higher than the specified DC voltage
In the high voltage generating circuit for generating the high voltage applied to the circuit having the bets, have a predetermined frequency, and the pulse signal generating means for generating a different pair of pulse signals having polarities, the DC blocking function of the capacitive component, a DC component removing means for removing the respective DC components of a pair of pulse signals output from said pulse signal generating means, a pair that is removes the DC component by the DC component removing means
The pulse signal, the inside of the Cockcroft-Walton times
Enter the pair of input ends of the road-construction with obtaining the high voltage by boosting rectifying a pair of pulse signals, the one
Connect the input terminal of one of the pair of pulse signals
A high voltage generating circuit comprising: a boost rectifier that is grounded via a resistor; and a booster that boosts the predetermined DC voltage to obtain a power supply voltage of the pulse generator. 2. A high voltage applied to a light receiving element in a receiving circuit.
2. The high-voltage generating circuit according to claim 1, wherein said predetermined DC voltage is a signal received from said light receiving element.
A high-voltage generating circuit, which is a power supply voltage of the receiving circuit that processes the signal.