JP5190103B2 - Voltage generator, current generator - Google Patents

Description

  The present invention provides a voltage generator with an output current limiting function for controlling a voltage applied to a load while limiting an output current, and an output voltage limiting function for controlling a current flowing through the load after limiting an output voltage. The present invention relates to a current generator.

  As a voltage generator with an output current limiting function for controlling the voltage applied to the load after limiting the output current, the voltage generator described in Patent Document 1 (in Patent Document 1, “amplifier with a switching control circuit”) Is known as prior art. In FIG. 1, the structure of the voltage generator of patent document 1 is shown. The voltage generator 900 selects one of the first, second, and third input amplifying units 110, 120, and 130 according to the input signal, and the control amplification connected to the load by the output of the selected input amplifying unit. The unit 140 is controlled. The voltage generator 900 includes saturation prevention circuits 819, 829, 839, a diode switch 910, first and second voltage / current conversion circuits, voltage feedback means, and current feedback means. The diode switch 910 is provided on the output side of the first, second, and third input amplifying units 110, 120, and 130, and the first and second input amplifying units 110 according to the output voltage of these input amplifying units. The voltage corresponding to the lower one of the output voltages of 120 and 120 is applied to the positive output terminal 901, and the voltage corresponding to the higher one of the output voltages of the second and third input amplifiers 120 and 130 is applied to the negative output terminal 902, respectively. Output. The first voltage / current conversion circuit includes a transistor 203, resistors 711 and 721, and a Zener diode 981. The second voltage / current conversion circuit includes a transistor 204, resistors 712 and 722, and a Zener diode 982. The first and second voltage / current conversion circuits are connected to the positive output terminal 901 and the negative output terminal 902 of the diode switch 910, respectively, convert the input voltage into a positive current and a negative current, and convert the converted positive current and negative current. The output voltage resulting from the current relationship is supplied to the control amplifier 140 as a control input. The voltage feedback means includes an amplifying unit 160 and a resistor 702, and feeds back the voltage of the load 758 to the input side of the second input amplifying unit 120. The current feedback means includes an amplification unit 150 and resistors 746, 747, 748, 749, 704, 706, detects the current flowing through the load 758 as the voltage of the resistor 759, and detects the detected voltage as the first and third voltages. Are fed back to the input side of the input amplifiers 110 and 130.

No. 07-44095

  However, the voltage generator shown in FIG. 1 has a problem that the accuracy of limiting the output current decreases as the output voltage increases. It is an object of the present invention to provide a voltage generator that can generate a higher voltage without degrading the accuracy of limiting the output current.

  The voltage generator of the present invention controls the voltage applied to the load after limiting the output current. The voltage generator of the present invention includes a first, second and third input amplifying units, a saturation prevention circuit provided in each of the first, second and third input amplifying units, a current feedback means, a voltage A feedback means, an output amplifier, a diode switch, and an output controller are provided. A voltage corresponding to the limit value of the output current in a predetermined direction is input to the first input amplifier. The predetermined direction is a direction determined in advance from which of the loads current flows. A voltage for controlling the output voltage is input to the second input amplifier. A voltage corresponding to the limit value of the output current in the reverse direction of the predetermined direction is input to the third input amplifier. The current feedback means detects the voltage of the current detection resistor connected in series to the load at the terminal of the load whose potential is close to ground, and the detected voltage is input to the input side of the first and third input amplifying units. Return to The voltage feedback means feeds back a voltage corresponding to the voltage applied to the load to the input side of the second input amplifier. The output amplifier includes a first output amplifier that applies a voltage to the load so that current flows in the reverse direction, and a second output amplifier that applies a voltage to the load so that current flows in a predetermined direction. The diode switch is provided on the output side of the first, second, and third input amplifiers, and the lower one of the output voltages of the first and second input amplifiers according to the output voltages of these input amplifiers. Is output to the positive output terminal, and the voltage corresponding to the higher one of the output voltages of the second and third input amplifiers is output to the negative output terminal. The output control unit selects and controls the first output amplifier or the second output amplifier according to the outputs of the positive output terminal and the negative output terminal.

  When the voltage corresponding to the output voltage of the first input amplifier is output from the positive output terminal, the voltage generator of the present invention uses the second output amplifier to generate a current in a predetermined direction. The current is limited to the current corresponding to the input of one input amplifier. When a voltage corresponding to the output voltage of the second input amplifying unit is output from the positive output terminal and the negative output terminal, the second output is input to the load using the first output amplifier or the second output amplifier. A voltage according to the input of the amplifying unit is applied. When a voltage corresponding to the output voltage of the third input amplifying unit is output from the negative output terminal, the reverse current is determined according to the input of the third input amplifying unit using the first output amplifier. Limit to current.

  The current generator of the present invention can be realized by changing the voltage feedback means and the current feedback means of the voltage generator described above. The current generator of the present invention controls the current flowing to the load after limiting the output voltage. The current generator according to the present invention includes a first, second, and third input amplifying units, a saturation prevention circuit provided in each of the first, second, and third input amplifying units, a current feedback unit, a voltage A feedback means, an output amplifier, a diode switch, and an output controller are provided. A voltage corresponding to the limit value of the output voltage in a predetermined direction is input to the first input amplifier. A voltage for controlling the output current is input to the second input amplifier. A voltage corresponding to the limit value of the output voltage in the reverse direction of the predetermined direction is input to the third input amplifier. The current feedback means detects the voltage of the current detection resistor connected in series to the load at the terminal of the load whose potential is close to ground, and feeds back the detected voltage to the input side of the second input amplifier. . The voltage feedback means feeds back a voltage corresponding to the voltage applied to the load to the input side of the first and third input amplifiers. The output amplifier includes a first output amplifier that applies a voltage to the load so that current flows in the reverse direction, and a second output amplifier that applies a voltage to the load so that current flows in a predetermined direction. The diode switch is provided on the output side of the first, second, and third input amplifiers, and the lower one of the output voltages of the first and second input amplifiers according to the output voltages of these input amplifiers. Is output to the positive output terminal, and the voltage corresponding to the higher one of the output voltages of the second and third input amplifiers is output to the negative output terminal. The output control unit selects and controls the first output amplifier or the second output amplifier according to the outputs of the positive output terminal and the negative output terminal.

  When the voltage corresponding to the output voltage of the first input amplification unit is output from the positive output terminal, the current generator of the present invention uses the second output amplifier to generate the voltage in the predetermined direction. 1 is limited to a voltage corresponding to the input of the input amplifying unit. When a voltage corresponding to the output voltage of the second input amplifying unit is output from the positive output terminal and the negative output terminal, the second output is input to the load using the first output amplifier or the second output amplifier. A current corresponding to the input of the amplifying unit is supplied. When a voltage corresponding to the output voltage of the third input amplifying unit is output from the negative output terminal, the reverse voltage is determined according to the input of the third input amplifying unit using the first output amplifier. Limit to voltage.

  According to the voltage generator of the present invention, since the resistor for detecting the current flowing through the load is connected to the terminal of the load whose potential is close to the ground, it is not affected by the voltage applied to the load during current detection. . Therefore, since the common-mode signal does not affect, the output current can be limited with high accuracy even if a high voltage is generated in the load. In addition, according to the current generator of the present invention, the output amplifying unit is provided in the same manner as the voltage generator described above, and the current detection resistor is connected to the load terminal whose load potential is close to ground. Even when a current that generates a high voltage is applied to the load, the output current can be controlled with high accuracy without being affected by the voltage generated in the load.

The figure which shows the structure of the conventional voltage generator. 1 is a diagram illustrating a configuration example of a voltage generation device according to a first embodiment. The figure which shows the structural example of a saturation prevention circuit. The figure for demonstrating operation | movement of the voltage generator of Example 1 in the 1st case. The figure for demonstrating operation | movement of the voltage generator of Example 1 in the 2nd case. The figure for demonstrating operation | movement of the voltage generator of Example 1 in the 3rd case. The figure for demonstrating operation | movement of the voltage generator of Example 1 in the 4th case. 1 is a diagram illustrating a configuration example of a voltage generator according to a first modification. The figure which shows the structural example of the voltage generator of Example 1 modification 2. FIG. The figure which shows the structural example of the voltage generator of Example 1 modification 3. FIG. The figure which shows the structural example of the electric current generator of Example 2. FIG. The figure for demonstrating operation | movement of the electric current generator of Example 2 in the 1st case. The figure for demonstrating operation | movement of the electric current generator of Example 2 in the 2nd case. The figure for demonstrating operation | movement of the electric current generator of Example 2 in the 3rd case. The figure for demonstrating operation | movement of the electric current generator of Example 2 in the 4th case. FIG. 7 is a diagram illustrating a configuration example of a current generating device according to a first modification. FIG. 7 is a diagram illustrating a configuration example of a current generator according to a second modification example. FIG. 10 is a diagram illustrating a configuration example of a current generator according to a second modification example of the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same number is attached | subjected to the structure part which has the same function, and duplication description is abbreviate | omitted.

[analysis]
First, the reason why the common-mode rejection ratio deteriorates when the output voltage _VO is increased in the conventional voltage generator of FIG. In FIG. 1, one end of the load 758 is grounded, and the potential of the other end (side connected to the terminal 558) is _VO volts. Here, the resistances of the resistors 759, 746, 747, 748, and 749 are R _s ohm, R _a ohm, R _b ohm, R _c ohm, and R _d ohm, respectively. Further, the amplification factor of the amplifier 150 _{A 5, V M} V output side potential of the amplifying unit 150, a voltage generated across the resistor 759 and ΔV volts.
At this time, the potential of the potential _{V +} and the terminal 568 of the terminal 569 V _-, respectively

It is. The difference between these potentials is inputted to the amplifier 150, the potential V _M can be determined as follows.

From equation (1), the gain of the _{A d} of ΔV is the differential voltage, the gain of the _{V O} is common mode voltage and _{A c,}

It becomes.
Here, the common-mode rejection ratio (CMRR) will be examined. The common-mode signal rejection ratio is obtained by dividing the differential gain by the common-mode gain. The larger the common-mode signal rejection ratio, the smaller the influence of the common-mode voltage. CMRR (dB) can be obtained from the equations (2) and (3) as follows.

In principle, the CMRR can be made infinite if the resistance is selected so that R _b R _c = R _a R _d , but there is a limit in reality. For example, _let us consider a case where the voltage generated by ΔV which is a voltage for feeding back a current value among components of CMRR of 100 dB and VM is 1V. If the output voltage _{V O} is 10V, components of _{V M} generated by the output voltage _{V O} is 0.0001. However, if the output voltage _{V O} is 1000V, components of _{V M} generated by the output voltage _{V O} is 0.01 V. Thus, as the output voltage increases, the influence of V _O that is the in-phase component increases. This is considered to be a cause of lowering the accuracy of limiting the output current when a high voltage is to be generated.

[Configuration example]
FIG. 2 shows a configuration example of the voltage generator of the first embodiment. The voltage generator 100 controls the voltage applied to the load 752 after limiting the output current. The voltage generator 100 includes first, second, and third input amplification units 110, 120, and 130, and saturation prevention circuits 810, 820, and 830 provided in the first, second, and third input amplification units, respectively. A current feedback unit, a voltage feedback unit, an output amplifier 210, a diode switch 910, and an output controller 230.

In the example of FIG. 2, the non-inverting input side of the first input amplifying unit 110 is grounded, and the voltage for setting the limit value of the output current in a predetermined direction via the resistor 703 is connected to the inverting input side ( -V ₁ ), the voltage fed back by the current feedback means, and the voltage from the saturation prevention circuit 810 are input. As described above, the first input amplifier 110 receives a voltage corresponding to the output current limit value in a predetermined direction. The predetermined direction is a direction determined in advance from which of the loads current flows. In this embodiment, the direction of the current flowing from the terminal 553 side to the terminal 552 side with respect to the load 752 is set as a predetermined direction.

In the example of FIG. 2, the non-inverting input side of the second input amplifying unit 120 is also grounded, and the voltage (± V ₂ ) and voltage for controlling the output voltage via the resistor 701 are connected to the inverting input side. The voltage fed back by the feedback means and the voltage from the saturation prevention circuit 820 are input. As described above, the voltage for controlling the output voltage is input to the second input amplifier 120.

In the example of FIG. 2, the non-inverting input side of the third input amplifying unit 130 is also grounded, and a voltage (for setting a limit value of an output current in a predetermined direction via a resistor 705 is connected to the inverting input side. V ₃ ), the voltage fed back by the current feedback means, and the voltage from the saturation prevention circuit 830 are input. Thus, the voltage corresponding to the limit value of the output current in the reverse direction of the predetermined direction is input to the third input amplifier 130.

In the example of FIG. 2, the current feedback means includes an amplification unit 150 and resistors 751, 741, 742, 743, 744, 704, and 706. The current detection resistor 751 serves to convert the current _IO flowing through the load 752 into a voltage, and the current feedback means feeds back a voltage proportional to the current _IO (voltage ΔV across the current detection resistor 751). ing. In this way, the current feedback means detects the voltage of the current detection resistor 751 connected in series with the load 752 to the terminal 552 whose potential of the load 752 is close to ground, and the detected voltage is the first and first voltages. Feedback to the input side of the three input amplifying units 110 and 130.

In the example of FIG. 2, the voltage feedback means includes an amplification unit 160 and a resistor 702. The non-inverting input of the amplifier 160 is input voltage V _R of the terminal 553, to the inverting input side output of the amplifier 160 is fed back. Thus, the voltage feedback means for feeding back the voltage V _R corresponding to the voltage V _O to be applied to the load 752 to the input side of the second input amplifier 120. The voltage V _R is the sum of the voltage V _O and the voltage ΔV. If the resistance value _RS of the resistor 751 is sufficiently smaller than the resistance value R _L of the load 752, V _R ≈V _O. because, it can be considered that the voltage feedback means, for feeding back the voltage V _O to be applied to the load 752.

  In the example of FIG. 2, the output amplifier 210 includes a first output amplifier 201, a second output amplifier 202, power supplies 154 and 155, and resistors 731 and 732. The first output amplifier 201 is an npn transistor, and a power source 154 is connected to the collector, and a resistor 731 is connected between the emitter and the ground. And the output from the output control part 230 is input into a base. The second output amplifier 202 is a pnp type transistor, and a power source 155 is connected to the collector, and a resistor 732 is connected between the emitter and the ground. And the output from the output control part 230 is input into a base. The first output amplifier 201 applies a voltage to the load 752 so that a current flows in the reverse direction. The second output amplifier 202 applies a voltage to the load 752 so that a current flows in a predetermined direction.

In the example of FIG. 2, the diode switch 910 includes four diodes 911, 912, 913, and 914 and is provided on the output side of the first, second, and third input amplification units 110, 120, and 130. . By the diode 911 and the diode 912, the lower of the output voltage _{V a2} and the output voltage _{V a1} of the first input amplifier unit 110 and the second input amplifier 120 is selected. The potential _V a1 + _{V F} or _V a2 + _{V F} where the potential difference _{V F} addition occurring between the terminals of the diode is output to the positive output terminal 901. By a diode 913 and a diode 914, a higher output voltage _{V a3} between the output voltage _{V a2} of the second input amplifier 120 third input amplifier 130 is selected. The potential _V a2 -V _F or _V a3 -V _F minus the potential difference _{V F} generated between terminals of the diode is outputted to the negative output terminal 902. As described above, the diode switch 910 has the output voltage of the first and second input amplifiers 110 and 120 in accordance with the output voltages (V _a1 , V _a2 , and V _a3 ) of the input amplifiers 110, 120, and 130. The voltage corresponding to the lower one is output to the positive output terminal 901, and the voltage corresponding to the higher one of the output voltages of the second and third input amplifiers 120, 130 is output to the negative output terminal 902.

  In the example of FIG. 2, the output control unit 230 includes transistors 203 and 204, resistors 711, 721, 712, and 722, Zener diodes 981 and 982, and diodes 921 and 922. The transistor 203 is a pnp type transistor, and the emitter is connected to a power supply (voltage + V) via a resistor 721. The base is connected to a power supply (voltage + V) through a resistor 711 and is connected to a positive output terminal 901 through a Zener diode 981. The transistor 204 is an npn-type transistor, and the emitter is connected to a power supply (voltage −V) via a resistor 722. The base is connected to a power supply (voltage −V) through a resistor 712 and connected to a negative output terminal 902 through a Zener diode 982. The collector of the transistor 203 and the collector of the transistor 204 are connected via diodes 921 and 922. The collector of the transistor 203 is connected to a terminal 541 connected to the first output amplifier 201, and the collector of the transistor 204 is connected to a terminal 542 connected to the second output amplifier 202. Then, the output control unit 230 selects and controls the first output amplifier or the second output amplifier according to the outputs of the positive output terminal and the negative output terminal.

  FIG. 3 shows a configuration example of the saturation prevention circuit. The saturation prevention circuit may be the circuit used in Patent Document 1, but may have the configuration shown in FIG. A necessary condition is that the potential difference between the input and output of the input amplifier 120 is limited to be smaller than the potential difference between the input and output of the input amplifiers 110 and 130. In both the case of FIG. 3A and the case of FIG. 3B, the number of diodes connected in series in the saturation prevention circuit 820 is larger than the number of diodes connected in series in the saturation prevention circuits 810 and 830. Therefore, the potential difference between the input and output is limited to be small by the potential difference of one diode. In this way, the saturation prevention circuits 810, 820, and 830 may be combined.

[Operation]
The voltage generator 100 is configured as described above, and operates as follows. Here will be described with divided when the output voltage V _M of the amplification unit 150. The resistance values of the resistors 701, 702, 703, 704, 705, 706, 751, 741, 742, 743, 744 are set to R ₁ ohm, R ₂ ohm, R ₃ ohm, R ₄ ohm, R ₅ ohm, R ₆ ohm, Let R _S ohm, R _a ohm, R _b ohm, R _c ohm, R _d ohm.
First, using FIG.

The operation in the case of will be described. In this case, a positive voltage (+ V ₂ ) is input to the input amplifier 120, and the output voltage V _a2 of the second input amplifier 120 is a negative voltage within the operating range of the second input amplifier 120. It becomes. For example, a voltage of −0.6 to 0 V is output. In addition, the output voltage V _a1 of the first input amplifying unit 110 is positively saturated, and the output voltage V _a3 of the third input amplifying unit 130 is negatively saturated. Therefore, a voltage corresponding to the output voltage _Va2 of the second input amplifier 120 is output from the positive output terminal 901 and the negative output terminal 902. Specifically, the potential of the positive output terminal 901 is V _a2 + V _F , and the potential of the negative output terminal 902 is V _a2 −V _F. The base potentials of the transistors 203 and 204 are V _a2 + V _F + V _T and V _a2 −V _F −V _T , respectively. Note that V _T is a voltage between the terminals of the Zener diodes 981 and 982. Since the output voltage V _a2 is negative, the absolute value of the output from the negative output terminal 902 is larger than the absolute value of the output from the positive output terminal 901. In this case, since the potential of the terminal 541 is positive, the first output amplifier 201 operates. Then, the potential _{V R} of the terminal 553 is fed back to the second input amplifier 120 by the voltage feedback means. In the example of FIG. 2, when the output voltage of the amplifier 160 and _{V a6,} the relationship between the potential _{V R} and the input voltage _{V 2} and the output voltage _{V a6,}

It becomes. Further, the voltage V _O applied to the load 752 and the flowing current I _O are obtained as follows.

That is, the first output amplifier 201 applies a voltage V _O corresponding to the input (+ V ₂ ) of the second input amplification unit 120 to the load 752.
Next, using FIG.

The operation in the case of will be described. In this case, a negative voltage (−V ₂ ) is input to the input amplifying unit 120, and the output voltage V _a2 of the second input amplifying unit 120 is positive within the operating range of the second input amplifying unit 120. Voltage. For example, a voltage of 0 to 0.6V is output. In addition, the output voltage V _a1 of the first input amplifying unit 110 is positively saturated, and the output voltage V _a3 of the third input amplifying unit 130 is negatively saturated. Therefore, a voltage corresponding to the output voltage _Va2 of the second input amplifier 120 is output from the positive output terminal 901 and the negative output terminal 902. Specifically, the potential of the positive output terminal 901 is V _a2 + V _F , and the potential of the negative output terminal 902 is V _a2 −V _F. The base potentials of the transistors 203 and 204 are V _a2 + V _F + V _T and V _a2 −V _F −V _T , respectively. Since the output voltage V _a2 is positive, the absolute value of the output from the positive output terminal 901 is larger than the absolute value of the output from the negative output terminal 902. In this case, since the potential of the terminal 542 becomes negative, the second output amplifier 202 operates. Then, the potential _{V R} of the terminal 553 is fed back to the second input amplifier 120 by the voltage feedback means. In the relationship between the potential _{V R} and the input voltage _{V 2} and the output voltage _{V a6} example of FIG. 2,

It becomes. Further, the voltage V _O applied to the load 752 and the flowing current I _O are obtained as follows.

That is, the voltage V _O corresponding to the input (−V ₂ ) of the second input amplifying unit 120 is applied to the load 752 using the second output amplifier 202.
Up to this point, the case where the voltage V _O corresponding to the input of the second input amplifying unit 120 is output has been described. Hereinafter, the case where the current flowing through the load 752 is limited will be described. First, using FIG.

The operation in the case of will be described. This case corresponds to the case where the current I _O reaches the limit while the positive voltage (+ V ₂ ) is input to the input amplifier 120, and the third input amplifier 130 corresponds to the current I _O. The voltage ΔV is fed back. The output voltage V _a1 of the first input amplifying unit 110 is positively saturated, and the output voltage V _a2 of the second input amplifying unit 120 is negatively saturated (for example, fixed at −0.6 V). . Then, a voltage corresponding to the output voltage V _a3 of the third input amplifier 130 is output from the negative output terminal 902. Specifically, the potential of the positive output terminal 901 is V _a2 + V _F , and the potential of the negative output terminal 902 is V _a3 −V _F. The base potentials of the transistors 203 and 204 are V _a2 + V _F + V _T and V _a3 −V _F −V _T , respectively. In this case, since the potential of the terminal 541 is positive, the first output amplifier 201 operates. The voltage ΔV between the terminals of the resistor 751 is fed back to the third input amplifier 130 by the current feedback means. In the example of FIG. 6, the relationship between the voltage ΔV between the input voltage V ₃ across the terminals of the output voltage V _M and the resistor 751 of the amplifier 150, the output current I _O is as follows. However, _{A 5} is the amplification factor of the amplifier 150.

In actual operation, A ₅ ≧ 1000,

Because it is designed to be

Can be operated. As described above, the first output amplifier 201 is used to limit the current in the reverse direction to a current corresponding to the input voltage V ₃ of the third input amplifier 130.
Next, using FIG.

The operation in the case of will be described. In this case corresponds to the case where current I _O reaches the limit in the state the input amplifier 120 to which a negative voltage (-V ₂₎ is input, the first input amplifier 110, the current I _O The corresponding voltage ΔV is fed back. The output voltage V _a2 of the second input amplification unit 120 is positively saturated (for example, fixed at 0.6 V), and the output voltage V _a3 of the third input amplification unit 130 is negatively saturated. Then, a voltage corresponding to the output voltage V _a1 of the first input amplifier 110 is output from the positive output terminal 901. Specifically, the potential of the positive output terminal 901 is V _a1 + V _F , and the potential of the negative output terminal 902 is V _a2 −V _F. The base potentials of the transistors 203 and 204 are V _a1 + V _F + V _T and V _a2 −V _F −V _T , respectively. In this case, since the potential of the terminal 542 becomes negative, the second output amplifier 202 operates. The voltage ΔV between the terminals of the resistor 751 is fed back to the first input amplifier 110 by the current feedback means. In the example of FIG. 7, the relationship between the voltage ΔV between the input voltage across the terminals of the output voltage _{V M} and the resistor 751 of the amplification unit 150 (-V _1), the output current _{I O} is as follows.

In actual operation, A ₅ ≧ 1000,

Because it is designed to be

Can be operated. As described above, the second output amplifier 202 is used to limit the current in a predetermined direction to a current corresponding to the input (−V ₁ ) of the first input amplification unit 110.

  The above operation will be described again according to the output from the diode switch 910 as follows. When a voltage corresponding to the output voltage of the first input amplifying unit 110 is output from the positive output terminal 901, the voltage generator 100 uses the second output amplifier 202 to output a current in a predetermined direction. The current is limited according to the input of the input amplifier 110 (see FIG. 7). When a voltage corresponding to the output voltage of the second input amplifying unit 120 is output from the positive output terminal 901 and the negative output terminal 902, the first output amplifier 201 or the second output amplifier 202 is used to load A voltage corresponding to the input of the second input amplifying unit 120 is applied to (see FIGS. 4 and 5). When a voltage corresponding to the output voltage of the third input amplifying unit 130 is output from the negative output terminal 902, the current in the reverse direction is supplied to the third input amplifying unit 130 using the first output amplifier 201. The current is limited according to the input (see FIG. 6).

[Confirmation of effect]
The current feedback means of the voltage generator 100 will be analyzed. As mentioned above

So, in theory, V _O does not affect the output voltage V _M of the amplification unit 150 is a common mode voltage. Therefore, it is not necessary to set R _b R _c = R _a R _d exactly as in the prior art.

According to the voltage generator 100, the resistor 751 for detecting the current _IO flowing through the load 752 is connected to the terminal 552 of the load 752 whose potential is close to ground, so that the voltage applied to the load 752 at the time of current detection. Not affected. Therefore, since the voltage applied to the load is not the common-mode signal of the current detection circuit, the output current can be limited with high accuracy even when a high voltage is generated.

[Modification 1]
FIG. 8 shows a configuration example of the voltage generator of the first modification example of the first embodiment. The voltage generator 101 is different from the voltage generator 100 of the first embodiment only in the output control unit. Specifically, in the voltage generator 101, the output control unit further includes a control amplification unit 140 and resistors 733, 734, 735, and 736. The collector of the transistor 203 and the collector of the transistor 204 are directly connected, and the two collectors are connected to the non-inverting input side of the control amplification unit 140. The output side is connected to the inverting input side via a resistor 735, and the inverting input side is connected to the ground via a resistor 736. Further, a resistor 733, a diode 921, a diode 922, and a resistor 734 are connected in series between the power source (voltage + V) and the power source (voltage -V). The output of the control amplification unit 140 is connected between the diode 921 and the diode 922. Further, the resistor 733 and the diode 921 are connected to the terminal 541 connected to the first output amplifier 201, and the diode 922 and the resistor 734 are connected to the terminal 542 connected to the second output amplifier 202. ing.

  Since the voltage generator 101 has such a configuration, the same effects as those of the first embodiment can be obtained. Furthermore, the input voltage to the first and second output amplifiers 201 and 202 can be changed in a wide range. In addition, since the input impedance can be increased by using an operational amplifier for the control amplification unit 140, the circuit of the output control unit 230 can be easily designed.

[Modification 2]
FIG. 9 shows an example of the configuration of the voltage generator of the first modification of the first embodiment. The voltage generator 102 is different from the voltage generator 100 of the first embodiment in voltage feedback means. Resistors 761, 762, 763, and 764 are further added to the voltage feedback means of the voltage generator 102. The terminal 553 is connected to the non-inverting input side of the amplification unit via the resistor 761. The non-inverting input side is connected to the ground via a resistor 762. The output side and the inverting input side of the amplifying unit 160 are connected via a resistor 764, and the inverting input side is connected to a terminal 552 via a resistor 763. Thus, in this voltage feedback means, the potential difference between both ends of the load 752 is input to the amplifying unit 160.

Therefore, ΔV can be removed from the feedback voltage after obtaining the effect of the first embodiment, so that the output voltage V _O can be controlled more accurately. This modification can be combined with the first modification of the first embodiment.

[Modification 3]
FIG. 10 shows a configuration example of the voltage generating apparatus according to the first modification of the first embodiment. The voltage generator 103 is different from the voltage generator 100 of the first embodiment in current feedback means. In the current feedback means of the voltage generator 103, the ground is between the load 752 and the resistor 751. Further, the resistors 741 and 742 are omitted, and the non-inverting input side of the amplifying unit 150 is grounded. Even with such a configuration, ΔV can be removed from the voltage fed back by the voltage feedback means. Therefore, on to obtain the effect of the first embodiment, it can be more accurately control the output voltage V _O. This modification can be combined with the first modification of the first embodiment.

  In the first embodiment, the voltage generator that controls the voltage applied to the load after limiting the output current has been described. In the second embodiment, a current generator that controls the current flowing through the load after limiting the output voltage will be described. FIG. 11 shows a configuration example of the current generator according to the second embodiment. The current generator 300 is the same as the voltage generator 100 of the first embodiment except for the input amplifier that is fed back by the voltage feedback unit and the current feedback unit, and the other configurations are the same. That is, the configuration of the output amplification unit 210, the configuration of the output control unit 230, the arrangement of the resistor 751 that converts the current flowing through the load into the voltage, which are the major differences between the conventional voltage generation device and the voltage generation device of the first embodiment, The current generator 300 and the voltage generator 100 are the same. In the following, the operation will be described after explaining the different parts.

In the example of FIG. 11, the current feedback means includes an amplifier 150 and resistors 751, 741, 742, 743, 744, and 792. The current detection resistor 751 serves to convert the current _IO flowing through the load 752 into a voltage, and the current feedback means feeds back a voltage proportional to the current _IO (voltage ΔV across the current detection resistor 751). ing. In this way, the current feedback means detects the voltage of the current detection resistor 751 connected in series with the load 752 at the terminal 552 whose potential of the load 752 is close to the ground, and the detected voltage is detected as the second input. Return to the input side of the amplifier 120.

In the example of FIG. 11, the voltage feedback means includes an amplification unit 160 and resistors 794 and 796. The non-inverting input of the amplifier 160 is input voltage V _R of the terminal 553, to the inverting input side output of the amplifier 160 is fed back. Thus, the voltage feedback means, for feeding back the voltage _{V R} corresponding to the voltage _{V O} to be applied to the load 752 to the first input side of the third input amplifier portion 110 and 130. The voltage V _R is the sum of the voltage V _O and the voltage ΔV. If the resistance value _RS of the resistor 751 is sufficiently smaller than the resistance value R _L of the load 752, V _R ≈V _O. because, it can be considered that the voltage feedback means, for feeding back the voltage V _O to be applied to the load 752.

[Operation]
The voltage generator 100 is configured as described above, and operates as follows. Here, the description will be made while classifying the output potential _Va6 of the amplifying unit 160. The resistance values of the resistors 701, 792, 703, 794, 705, 796, 751, 741, 742, 743, 744 are changed to R ₁ ohm, R ₂ ohm, R ₃ ohm, R ₄ ohm, R ₅ ohm, R ₆ ohm, Let R _S ohm, R _a ohm, R _b ohm, R _c ohm, R _d ohm.
First, using FIG.

The operation in the case of will be described. In this case, a positive voltage (+ V ₂ ) is input to the input amplifier 120, and the output voltage V _a2 of the second input amplifier 120 is a negative voltage within the operating range of the second input amplifier 120. It becomes. For example, a voltage of −0.6 to 0 V is output. In addition, the output voltage V _a1 of the first input amplifying unit 110 is positively saturated, and the output voltage V _a3 of the third input amplifying unit 130 is negatively saturated. Therefore, a voltage corresponding to the output voltage _Va2 of the second input amplifier 120 is output from the positive output terminal 901 and the negative output terminal 902. Specifically, the potential of the positive output terminal 901 is V _a2 + V _F , and the potential of the negative output terminal 902 is V _a2 −V _F. The base potentials of the transistors 203 and 204 are V _a2 + V _F + V _T and V _a2 −V _F −V _T , respectively. Note that V _T is a voltage between the terminals of the Zener diodes 981 and 982. Since the output voltage V _a2 is negative, the absolute value of the output from the positive output terminal 901 is smaller than the absolute value of the output from the negative output terminal 902. In this case, since the potential of the terminal 541 is positive, the first output amplifier 201 operates. The voltage ΔV between the terminals of the resistor 751 is fed back to the second input amplifier 120 by the current feedback means. In the example of FIG. 12, the relationship between the output voltage V _M of the amplification unit 150 and the voltage ΔV between the terminals of the resistor 751 and the input voltage V _2, the output current I _O is as follows. However, _{A 5} is the amplification factor of the amplifier 150.

In actual operation, A ₅ ≧ 1000,

Because it is designed to be

Can be operated. Thus, using the first output amplifier 201, a current in the reverse direction corresponding to the input of the second input amplifier 120 is passed through the load 752.
Next, using FIG.

The operation in the case of will be described. In this case, a negative voltage (−V ₂ ) is input to the input amplifying unit 120, and the output voltage V _a2 of the second input amplifying unit 120 is positive within the operating range of the second input amplifying unit 120. Voltage. For example, a voltage of 0 to 0.6V is output. In addition, the output voltage V _a1 of the first input amplifying unit 110 is positively saturated, and the output voltage V _a3 of the third input amplifying unit 130 is negatively saturated. Therefore, a voltage corresponding to the output voltage _Va2 of the second input amplifier 120 is output from the positive output terminal 901 and the negative output terminal 902. Specifically, the potential of the positive output terminal 901 is V _a2 + V _F , and the potential of the negative output terminal 902 is V _a2 −V _F. The base potentials of the transistors 203 and 204 are V _a2 + V _F + V _T and V _a2 −V _F −V _T , respectively. Since the output voltage V _a2 is positive, the absolute value of the output from the positive output terminal 901 is larger than the absolute value of the output from the negative output terminal 902. In this case, since the potential of the terminal 542 becomes negative, the second output amplifier 202 operates. The voltage ΔV between the terminals of the resistor 751 is fed back to the second input amplifier 120 by the current feedback means. In the example of FIG. 13, the relationship between the voltage ΔV between the input voltage across the terminals of the output voltage _{V M} and the resistor 751 of the amplification unit 150 (-V _2), the output current _{I O} is as follows.

In actual operation, A ₅ ≧ 1000,

Because it is designed to be

Can be operated. Thus, using the second output amplifier 202, a current in a predetermined direction corresponding to the input of the second input amplifier 120 is passed through the load 752.

Up to this point, the case where the current _IO corresponding to the input of the second input amplifying unit 120 is output has been described, but the case where the voltage applied to the load 752 is limited will be described below. First, using FIG.

The operation in the case of will be described. This case corresponds to the case where the voltage V _O reaches the limit with the positive voltage (+ V ₂ ) being input to the input amplifying unit 120, and the third input amplifying unit 130 corresponds to the voltage V _O. Voltage is fed back. The output voltage V _a1 of the first input amplifying unit 110 is positively saturated, and the output voltage V _a2 of the second input amplifying unit 120 is negatively saturated (for example, fixed at −0.6 V). . Then, a voltage corresponding to the output voltage V _a3 of the third input amplifier 130 is output from the negative output terminal 902. Specifically, the potential of the positive output terminal 901 is V _a2 + V _F , and the potential of the negative output terminal 902 is V _a3 −V _F. The base potentials of the transistors 203 and 204 are V _a2 + V _F + V _T and V _a3 −V _F −V _T , respectively. In this case, since the potential of the terminal 541 is positive, the first output amplifier 201 operates. Then, the potential _{V R} of the terminal 553 is fed back to the third input amplifier 130 by the voltage feedback means. In the example of FIG. 14, when the output voltage of the amplifier 160 and _{V a6,} the relationship between the output voltage _{V a6} and the input voltage _{V 3} and the voltage _{V R,}

It becomes. Further, the voltage V _O applied to the load 752 and the flowing current I _O are obtained as follows.

That is, the first output amplifier 201 limits the reverse voltage applied to the load 752 to a voltage corresponding to the input voltage V ₃ of the third input amplifier 130.
Next, using FIG.

The operation in the case of will be described. This case corresponds to the case where the voltage V _O reaches the limit with the negative voltage (−V ₂ ) being input to the input amplifier 120, and the first input amplifier 110 corresponds to the voltage V _O. Voltage is fed back. The output voltage V _a2 of the second input amplification unit 120 is positively saturated (for example, fixed at 0.6 V), and the output voltage V _a3 of the third input amplification unit 130 is negatively saturated. Then, a voltage corresponding to the output voltage V _a1 of the first input amplifier 110 is output from the positive output terminal 901. Specifically, the potential of the positive output terminal 901 is V _a1 + V _F , and the potential of the negative output terminal 902 is V _a2 −V _F. The base potentials of the transistors 203 and 204 are V _a1 + V _F + V _T and V _a2 −V _F −V _T , respectively. In this case, since the potential of the terminal 542 becomes negative, the second output amplifier 202 operates. Then, the potential _{V R} of the terminal 553 is fed back to the first input amplifier 110 by the voltage feedback means. In the relationship between the potential _{V R} input voltages _{V 1} and the output voltage _{V a6} example of FIG. 15,

It becomes. Further, the voltage V _O applied to the load 752 and the flowing current I _O are obtained as follows.

That is, the second output amplifier 202 is used to limit the voltage in a predetermined direction applied to the load 752 to a voltage corresponding to the input (−V ₁ ) of the first input amplifier 110.

  The above operation will be described again according to the output from the diode switch 910 as follows. When a voltage corresponding to the output voltage of the first input amplifying unit 110 is output from the positive output terminal 901, the current generator 300 uses the second output amplifier 202 to generate a voltage in a predetermined direction. Is limited to a voltage corresponding to the input of the input amplifier 110 (see FIG. 15). When a voltage corresponding to the output voltage of the second input amplifying unit 120 is output from the positive output terminal 901 and the negative output terminal 902, the first output amplifier 201 or the second output amplifier 202 is used to load A current corresponding to the input of the second input amplifying unit 120 is passed through (see FIGS. 12 and 13). When a voltage corresponding to the output voltage of the third input amplifying unit 130 is output from the negative output terminal 902, the reverse voltage is output from the third input amplifying unit 130 using the first output amplifier 201. The voltage is limited according to the input (see FIG. 14).

[Confirmation of effect]
For even current feedback means of a current generator 300, the equation (5) holds, in theory, V _O does not affect the output voltage V _M of the amplification unit 150 is a common mode voltage. Therefore, it is not necessary to keep low the voltage V _O to current control with high accuracy as in the prior art.

According to the current generator 300, since the resistor 751 for detecting the current _IO flowing through the load 752 is connected to the terminal 552 of the load 752 whose potential is close to ground, the voltage applied to the load 752 at the time of detecting the current. Not affected. Accordingly, current can be controlled to high take high accuracy a voltage V _O. Therefore, it is possible to flow a current _IO that generates a high voltage in the load 752.

[Modification 1]
In FIG. 16, the structural example of the electric current generator of Example 2 modification 1 is shown. The current generator 301 is different from the current generator 300 of the second embodiment only in the output control unit. Specifically, in the current generator 301, the output control unit further includes a control amplification unit 140 and resistors 733, 734, 735, and 736. The collector of the transistor 203 and the collector of the transistor 204 are directly connected, and the two collectors are connected to the non-inverting input side of the control amplification unit 140. The output side is connected to the inverting input side via a resistor 735, and the inverting input side is connected to the ground via a resistor 736. Further, a resistor 733, a diode 921, a diode 922, and a resistor 734 are connected in series between the power source (voltage + V) and the power source (voltage -V). The output of the control amplification unit 140 is connected between the diode 921 and the diode 922. Further, the resistor 733 and the diode 921 are connected to the terminal 541 connected to the first output amplifier 201, and the diode 922 and the resistor 734 are connected to the terminal 542 connected to the second output amplifier 202. ing.

  Since the current generator 301 has such a configuration, the same effect as that of the second embodiment can be obtained. Furthermore, the input voltage to the first and second output amplifiers 201 and 202 can be changed in a wide range. In addition, since the input impedance can be increased by using an operational amplifier for the control amplification unit 140, the circuit of the output control unit 230 can be easily designed.

[Modification 2]
FIG. 17 shows a configuration example of the current generator of the second modification of the second embodiment. The current generator 302 is different from the current generator 300 of the second embodiment in voltage feedback means. Resistors 761, 762, 763, and 764 are further added to the voltage feedback means of the current generator 302. The terminal 553 is connected to the non-inverting input side of the amplification unit via the resistor 761. The non-inverting input side is connected to the ground via a resistor 762. The output side and the inverting input side of the amplifying unit 160 are connected via a resistor 764, and the inverting input side is connected to a terminal 552 via a resistor 763. Thus, in this voltage feedback means, the potential difference between both ends of the load 752 is input to the amplifying unit 160.

Therefore, ΔV can be removed from the feedback voltage after obtaining the effect of the second embodiment, so that the output voltage V _O can be more accurately limited. This modification can be combined with the modification 1 of the second embodiment.

[Modification 3]
FIG. 18 shows a configuration example of the current generator of the second modification of the second embodiment. The current generator 303 is different from the current generator 300 of the second embodiment in current feedback means. In the current feedback means of the current generator 303, the ground is between the load 752 and the resistor 751. Further, the resistors 741 and 742 are omitted, and the non-inverting input side of the amplifying unit 150 is grounded. Even with such a configuration, ΔV can be removed from the voltage fed back by the voltage feedback means. Therefore, the output voltage V _O can be more accurately limited after obtaining the effects of the second embodiment. This modification can be combined with the modification 1 of the second embodiment.

100, 101, 102, 103, 900 Voltage generator 110, 120, 130 Input amplification unit 140 Control amplification unit 150, 160 Amplification unit 154, 155 Power supply 201, 202 Output amplifier 203, 204 Transistor 210 Output amplification unit 230 Output control unit 300, 301, 302, 303 Current generators 541, 542, 552, 553, 558 Terminals 701, 702, 703, 704, 705, 706, 711, 712, 721, 722, 731, 732, 733, 734, 735, 736, 741, 742, 743, 744, 746, 747, 748, 749, 751, 759, 761, 762, 763, 764, 792, 794, 796 Resistor 752, 758 Load 810, 819, 820, 829, 830, 839 Saturation prevention circuit 901 Terminal 902 negative output terminal 910 diode switch 911,912,913,914,921,922 diodes 981, 982 Zener diode

Claims (4)

A voltage generator with an output current limiting function that controls the voltage applied to the load after limiting the output current,
A first input amplifying unit to which a voltage corresponding to the limit value of the output current in a predetermined direction is input;
A second input amplifier to which a voltage for controlling the output voltage is input;
A third input amplifying unit to which a voltage corresponding to the limit value of the output current in the reverse direction of the predetermined direction is input;
A saturation prevention circuit provided in each of the first, second, and third input amplifying units;
The voltage of the current detection resistor connected in series with the load is detected at a terminal whose potential of the load is close to ground, and the detected voltage is fed back to the input side of the first and third input amplifiers. Current feedback means to
Voltage feedback means for feeding back a voltage corresponding to the voltage applied to the load to the input side of the second input amplifier;
An output amplifier having a first output amplifier that applies a voltage to the load so that current flows in the reverse direction, and a second output amplifier that applies a voltage to the load so that current flows in the predetermined direction When,
Provided on the output side of the first, second, and third input amplifying units, corresponding to the lower one of the output voltages of the first and second input amplifying units according to the output voltage of these input amplifying units A diode switch for outputting the voltage corresponding to the higher one of the output voltages of the second and third input amplifying units to the negative output terminal,
An output control unit that selects and controls the first output amplifier or the second output amplifier according to the outputs of the positive output terminal and the negative output terminal;
The connecting portion between the load and the current detection resistor is grounded,
When a voltage corresponding to the output voltage of the first input amplifying unit is output from the positive output terminal, the second input amplifier is used to convert the current in the predetermined direction into the first input amplifying unit. Limit the current according to the input of
When a voltage corresponding to the output voltage of the second input amplification unit is output from the positive output terminal and the negative output terminal, the first output amplifier or the second output amplifier is used, Apply a voltage according to the input of the second input amplifier to the load,
When a voltage corresponding to the output voltage of the third input amplifying unit is output from the negative output terminal, the reverse current is supplied to the third input amplifying unit using the first output amplifier. The voltage generator is characterized in that it is limited to a current according to the input. The voltage generator according to claim 1,
The output control unit includes a control amplification unit that amplifies a voltage corresponding to outputs from the positive output terminal and the negative output terminal. A current generator with an output voltage limiting function that controls the current flowing to the load after limiting the output voltage,
A first input amplifying unit to which a voltage corresponding to an output voltage limit value in a predetermined direction is input;
A second input amplifying unit to which a voltage for controlling the output current is input;
A third input amplifying unit to which a voltage corresponding to the limit value of the output voltage in the reverse direction of the predetermined direction is input;
A saturation prevention circuit provided in each of the first, second, and third input amplifying units;
Current feedback for detecting the voltage of a current detection resistor connected in series with the load at a terminal whose load potential is close to ground, and feeding back the detected voltage to the input side of the second input amplifying unit. Means,
Voltage feedback means for feeding back a voltage corresponding to a voltage applied to the load to the input side of the first and third input amplifying units;
An output amplifier having a first output amplifier that applies a voltage to the load so that current flows in the reverse direction, and a second output amplifier that applies a voltage to the load so that current flows in the predetermined direction When,
Provided on the output side of the first, second, and third input amplifying units, corresponding to the lower one of the output voltages of the first and second input amplifying units according to the output voltage of these input amplifying units A diode switch for outputting the voltage corresponding to the higher one of the output voltages of the second and third input amplifying units to the negative output terminal,
An output control unit that selects and controls the first output amplifier or the second output amplifier according to the outputs of the positive output terminal and the negative output terminal;
The connecting portion between the load and the current detection resistor is grounded,
When a voltage corresponding to the output voltage of the first input amplifying unit is output from the positive output terminal, the voltage in the predetermined direction is converted to the first input amplifying unit using the second output amplifier. Limited to the voltage according to the input of
When a voltage corresponding to the output voltage of the second input amplification unit is output from the positive output terminal and the negative output terminal, the first output amplifier or the second output amplifier is used, A current corresponding to the input of the second input amplifier is passed through the load;
When a voltage corresponding to the output voltage of the third input amplifier is output from the negative output terminal, the reverse voltage is converted to the third input amplifier using the first output amplifier. The current generator is characterized in that it is limited to a voltage according to the input. The current generator according to claim 3 ,
The output control unit includes a control amplification unit that amplifies a voltage corresponding to outputs from the positive output terminal and the negative output terminal.

Images