JP3190707B2 - Clamp type current-voltage converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current-to-voltage conversion circuit for converting a current signal to a voltage signal, and more particularly to an improvement in a current-to-voltage conversion circuit for clamping an output voltage to a certain potential.

[0002]

BACKGROUND OF THE INVENTION Clamp-type current voltage are conventionally used converter circuit 1, as shown in FIG. 6, established the amplifier 4 having an input terminal 2 and the negative-phase output terminal 5, an input terminal 2 between reverse phase output terminal 5 to connect the resistor 7. In addition, the resistor 7
Collector to the input terminal 2 and is, to install a transistor 6 which connects the emitter to the negative-phase output terminal 5.

[0003] transistor 6 base - scan is connected to an external voltage source circuits 18 to determine the clamp potential, the potential of the negative-phase output terminal 5, on the basis of the output potential of the external voltage source circuits 18 The transistor 6 is clamped so as not to fall below the base emitter forward saturation voltage.

[0004]

THE INVENTION Problems to be Solved] In such clamp-type current-voltage conversion circuit 1, the output potential of the negative phase of the output terminal 5 potential and an external voltage source circuitry 18 when the input current does not flow, the temperature It is necessary that the characteristics, the power supply voltage characteristics, and the dependence on semiconductor manufacturing conditions are uniform.

Namely, negative-phase output terminal when no input current is 5
Potential of temperature variations, voltage and current fluctuations or outside, such as variations in the semiconductor manufacturing conditions and varies with other factors, must also be changed in the same way the output potential of the external voltage source circuitry 18.

[0006] If the change of the negative-phase output potential as the external output potential and an external output potential does not match, the external voltage source the output voltage temperature variations or supply voltage variation or the semiconductor manufacturing conditions vary in the opposite phase output voltage On the other hand, the transistor 6
In some cases, the voltage becomes higher than the emitter forward saturation voltage.

[0007] In this case, even if no current flows, takes the voltage clamp to the negative-phase output <br/> pin 5, even if the input current is generated, negative-phase output terminal 5 voltage changes accordingly Not happen. That is, there is a difficulty that integrity issues an external voltage source circuitry 18 and the clamp-type current-voltage conversion circuit 1 is generated.

The present invention has been made under such circumstances. In particular, even when a temperature variation, a current-voltage variation, and a variation in semiconductor manufacturing conditions occur, the reverse-phase output potential is maintained when there is no input current. and the potential on the reference, base of the transistor - it is an object to provide a Suemitta forward saturation clamp-type current-voltage conversion circuits 1 does not drop than half the voltage.

[0009]

[MEANS FOR SOLVING THE PROBLEMS] An input terminal and a negative-phase output terminal
Child, the negative-phase output terminal the same potential when no input current
And the amplifier comprises a positive-phase output terminal for outputting a resistor to connect between the input terminal and the reverse phase output terminal, a collector to the input terminal, base on the positive phase output terminal - transistor coupling the scan There is a characteristic of the clamp-type current-voltage conversion circuit according to the present invention.

[0010]

As described above, according to the present invention, the input terminal, the positive-phase output terminal, and the negative-phase output terminal are provided in the amplifier, and the positive-phase output terminal potential and the negative-phase output terminal potential having the same characteristics are used. It is possible to eliminate adverse effects due to temperature fluctuations, power supply voltage fluctuations, and the like.

Even in such a situation, the potential of the negative-phase output terminal can always be clamped at a potential which is lower by half the base-emitter forward saturation voltage of the transistor.

As described above, in the clamp-type current-voltage conversion circuit according to the present invention, when the input range of the subordinate subsequent circuit is limited, for example, when the input range is set to 1 V, the clamp-type current-voltage conversion circuit is the preceding stage. Therefore, for a silicon process transistor having a forward saturation voltage of about 0.7 V, about 0.1 V is used. To 35v, approximately 0.15v if germanium process transistor forward saturation voltage of about 0.3 v, is intended to clamp.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to FIGS.

[0014] As revealed in Figure 1, the clamp-type current-voltage conversion circuit 1, the amplifier 4 to <br/> installed input terminal 2 and the negative phase output terminal 5 is arranged conventionally in Other it is characterized in that placing the positive phase output terminal 3. The installation of the transistor 6 is the same as the conventional one.

[0015] That is, the <br/> input terminal 5 out reverse phase emitter of the transistor 6, the outer of electrically sintered connection to the input terminal 2 of the collector, connecting the resistor 7 between the emitters of the transistors 6 and collector Further, the base of the transistor 6 is connected to the positive-phase output terminal 3 to form the clamp-type current-to-voltage conversion circuit 1.

[0016] In the clamp-type current-voltage conversion circuit 1 according to this circuit, the current input from the outside to the input terminal 2 is increased, the reverse phase output terminal 5 voltage is lowered and at the same the same amount by a positive phase output terminal child 3 voltage is increased. Normal phase output terminal 3
A potential difference between the negative-phase output terminal 5 of the transistor 6 base - Suetta upon reaching the forward saturation voltage, negative-phase output terminal 5
Power position is clamped.

[0017] That is, reverse phase output terminal 5 conductive position has an input terminal 2
On the basis of the time there is no current input to be of the transistor base - scan
It is clamped to the potential lower half of the emitter forward saturation voltage.

[0018] Figure 2, the positive phase output terminal 3 and the negative-phase output terminal
5 shows an example of circuit connection of the amplifying circuit 4 can output the same potential. As is apparent from this figure, comprise a reference voltage source 18 provided inside the four and five resistors and transistors. That is, the transistors 8 and 9 are connected to each other,
To a resistor 18, also connects the respective resistors 12 and 13 to the collector terminal. The base of the transistor 8 is used as an input terminal, and the base of the transistor 9 is connected to the reference voltage source 18.

The collector terminals of both transistors 8, 9 are:
Transistors 10 and 11 to reduce impedance
Of base - and scan and connected, resistance to each of the emitter terminal anti 15,1
With connecting 7, transistor 1 reverse phase output terminal 5
Connect to 0 and resistor 15 of the connection line. In addition, the positive phase output terminal
3, installed in the connecting line of the transistor 11 and the resistor 17. Further, resistor 15, 16 and 17 connected in common to constitute the amplifying unit 4 by connecting the collector terminal and resistor 12 and 13 of the transistors 10 and 11 in common. It should be noted that the resistor 12
And 13 and 15 and 17 are equivalent, respectively.
Is the resistance of the transistor pair 8, 9.

Even if the output potential of the reference voltage source changes due to temperature fluctuations, power supply voltage fluctuations, semiconductor manufacturing condition fluctuations, and the like, the base potential serving as the input terminal and the negative-phase output terminal when there is no input current. only the children 5 conductive position or the positive-phase output terminal 3 potential changes in the same manner, the clamp potential amount, or base - no effect on half of Sue emitter forward saturation voltage.

FIG. 3 shows an amplifier 4 which is simplified from FIG. That is, to form a positive-phase output terminal 3 and the negative-phase output terminal 5 to the clamp-type current-voltage conversion circuit 1 between the collector and resistor 12, 13 of the pair of transistors 8 and the transistor 9 of the differential amplifier Can also.

FIG. 4 shows another embodiment of the present invention. This example, by installing a resistor 19 between the emitter and the negative output terminal 5 of the transistor 6, it is possible to reduce the amount of negative feedback during clamping, oscillation hardly clamp-type current than in the first embodiment It is a voltage conversion circuit 1.

FIG. 5 shows the characteristics of the clamp-type current-to-voltage conversion circuit 1, in which the vertical axis represents the negative-phase output voltage or the positive-phase output voltage, and the horizontal axis represents the input current. . That is, the differential amplifier circuit characteristic according to the second view, and a pair of transistors 8 and 9, as revealed in FIG. 3 is shown in FIG. 5, the width of the dotted line in FIG, namely V f of the transistor base - Suemitta forward saturation voltage of about at an element made of silicon if example embodiment 0.7 V, the Ge element
It represents about 0.3V. It is clamped at half the potential of Vf. Slope when the clamp is not applied is, almost
Resistance becomes the anti-7 of the value Rf. Therefore, when the input voltage range of the subsequent circuit is specified to be, for example, 1 V, it is possible to limit the input voltage range by clamping, and the latter circuit can be reduced to about 0 if the silicon process transistor has a forward saturation voltage of about 0.7 V. In the case of a germanium process transistor having a forward saturation voltage of about 0.3 V and a forward saturation voltage of about 0.3 V, it operates stably at about 0.15 V.

[0024]

As described above, the clamp-type current-voltage conversion circuit according to the present invention uses the potential of the positive-phase output terminal and the potential of the negative-phase output terminal having the same characteristics in the amplifier. Even if voltage fluctuations and fluctuations in semiconductor manufacturing conditions occur, the negative-phase output terminal voltage can always be clamped at a potential lower by half the base-emitter forward saturation voltage of the transistor with respect to the input current.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a clamp-type current-voltage conversion circuit according to the present invention.

FIG. 2 is an example of an amplifier used in a clamp-type current-voltage conversion circuit according to the present invention.

FIG. 3 is a connection diagram showing another example of the amplifier used in the clamp-type current-voltage conversion circuit according to the present invention.

FIG. 4 is another embodiment of the clamp-type current-voltage conversion circuit according to the present invention.

FIG. 5 is a curve diagram showing characteristics of an amplifier used in the clamp-type current-voltage conversion circuit according to the present invention.

FIG. 6 is a connection diagram of a conventional clamp-type current-voltage conversion circuit.

[Explanation of symbols]

1: clamp-type current-voltage circuit , 2: input terminal, 3: positive-phase output terminal, 4: amplifier , 5: negative-phase output terminal 6, 8, 9, 10, 11: transistor, 7, 12, 13, 15. 16, 17, 19: resistance, 18: power supply.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03F 1/00-1/56 H03F 3/00-3/45 H03F 3/50-3/52

Claims (1)

(57) [Claims] An input terminal, a negative-phase output terminal , and an input current
Positive phase output that outputs the same potential as
And the amplifier comprises a power terminal, a resistor that connects between the input terminal and the reverse phase output terminal, a collector to the input terminal, base on the positive phase output terminal - to and a transistor which connects the scan Clamp-type current-voltage conversion circuit characterized by the following