JPS62149205A - Current conversion circuit - Google Patents

Abstract

PURPOSE:To attain the titled circuit with a high gain and to apply the circuit to a switching circuit or a rectangular conversion circuit or the like by providing a coupling circuit and a differential amplifier comprising plural transistors (TR) so as to attain the linear conversion. CONSTITUTION:TRs Qa1, Qa2 and Qb1, Qb2 constitute respectively the coupling circuits and bases of the TRs Qa1, Qb1 are connected to a bias power supply VB1. Further, the differential amplifier consists of TRs Qx, Qy and emitters of TRs Qa2, Qb2 are connected to the base of the TRs Qy, Qx. When a current IPa2 of a terminal Pa2 and a current Isb2 of a constant current source are made unequal to each other, one of the TRs Qx, Qy is conductive and the other is cut off momentarily and the state of currents IPx, IPy is changed over. Since the changeover has a characteristic with a rapid slope in this case, a high gain circuit is attained near the changeover, the circuit is applied to a rectangular wave conversion circuit or a signal discriminating circuit or the like and the linear conversion is attained.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a current conversion circuit, and particularly to a semiconductor integrated circuit (
It is easy to integrate into an IC) and is suitable for use in high gain amplifier circuits and the like.

[Technical background of the invention]

An example of a conventional current conversion type amplifier circuit is shown in FIG.

In FIG. 3, transistors Q1, Q2 each have their bases supplied with a voltage from a reference bias voltage source VBI, and emitters of transistors Q3, . . . , which constitute a differential amplifier.
Connected to the base of Q4. Each transistor Ql,
The collector of Q2 is connected to the voltage source Vcc, and the collector of transistor Q3. Input terminals Pl and P2 are connected to the base of Q4, and Q3. The emitters of Q4 are connected in common and connected to a reference potential point (earth) via a constant current source Isx. and transistor Q3. The collector of Q4 is output terminal P3. Connected to P4.

When determining the relationship between input and output in the circuit shown in FIG. 3, the following equation holds true from FIG.

VBI-VFI-#F4=VB1-VF2-VF3
-・-・ (1) Yotte Vyrx-1-VTP
4=VIPz−1−VF3−・−・(2) (However, VF
I~vF4 is the base-emitter voltage of the transistors Q~Q4. ) It is well known that the base-emitter junction of a transistor (including a diode) is given by the following equation.

T In VIP=-tn-・・・(3) 'It Is However, K is Boltzmann's constant and T is the absolute temperature.

In is the electron charge, and In is the emitter current of the transistor (
(substantially the collector current), Is is the saturation current of the transistor.If the circuit of FIG. 3 is constructed on a semiconductor substrate, the transistors Q] to Q4 can have substantially the same characteristics. By setting I8 of each transistor to be equal, the emitter current or collector current of each transistor is
px~IP4.

11=Ip1. l2=IP2. l3=Ip3. I4:I
It's F5.

Substituting equation (3) into equation (2) yields.

IPI・IP4=IP2・IF5
...(4) holds true. Also, the current value of the current source ISI is.

IS]=IP3+IP4...(
5), and it follows from equations (4) and (5).

In this way, an output signal responsive to the input signal is obtained at the output terminal.

[Problems with background technology]

What can be seen from the above equation (6) is that IPI or IF
If 5 is used as an input signal, IF5 does not become a linear output function, and although it has the advantage of being a current conversion type, linear conversion cannot be performed due to nonlinear conversion. Moreover, its applicability was limited.

[Purpose of the invention]

An object of the present invention is to provide a 4-current conversion circuit that is capable of linear conversion, can achieve a high gain circuit, and can be applied to a 2-switching circuit, a rectangular wave conversion circuit, 2-discrimination circuit, and the like.

[Summary of the invention]

The present invention has the following features: 1. The second transistor (QY.

QK) and 2m (m≧1) semiconductor junctions. Second junction circuit (Qax.

Qn2), (Qbx, Qbx), means for connecting the collector of the first transistor to the second junction circuit, and connecting the collector of the second transistor to the first junction circuit; an input current supply means connected to any part of the second junction circuit; 1. This is a 5Kt current conversion circuit that takes out an output (for example, a differential output) from a point (PY, PK) connected to the collector of the first and second transistors.

[Embodiments of the Invention] A circuit of the present invention will be described with reference to the drawings. Prior to the explanation, each symbol used in the two sentences will be defined as follows.

n as a subscript indicating a series of numbers Qn: Transistor.

Pn: terminal.

Vcc: Power supply and voltage value.

VBn: Bias power supply and bias voltage value.

The emitter current or collector current of In:Qn (when the current amplification factor is sufficiently large and the two are substantially equal) 7-' and the values of these currents.

value IPn: Current and current source flowing through Pn.

ISn: A constant current source and a constant current source value when In is particularly used as a current source.

FIG. 1 shows an embodiment of the present invention, in which (A) is a circuit diagram and (B) is a characteristic diagram. In FIG. 1(A), transistors Qal, Qn2 and Qb1°Qb2 each form a junction circuit, and the bases of Qal and Qbl are connected to a bias power supply VBI.

The emitter of Qal is connected to the base of Qn2, Qbl
The emitter of is connected to the base of Qb2 +Qa2+Q
The emitter of b2, that is, the output end of the junction circuit, is connected to the base of transistor Q, which constitutes a differential amplifier, and Qx. Further, the collector of Qy is connected to the emitter of Qbl, and the collector of Qx is connected to the emitter of Qal.

Terminal Pa2 is a current supply terminal connected to the emitter of transistor Qa2, and terminals Px and Py are respectively connected to transistors Qa1. Qb] is an output terminal connected to the collector of Qb]. Further, the common emitters of the transistors Qx and Qy are connected to a reference potential point (earth) via a current source Iso, and the emitter of the transistor Qb2 is connected to a current source l5b2. and transistor Qa2. Qbz
The collector of is connected to the voltage source VCCK.

Next, the operation of the circuit shown in FIG. 1(A) will be explained with reference to the characteristic diagram shown in FIG. 1(B). (A) From the diagram, Ia1=Ix
, Ib]=Iy, Iaz=Ipa2. Ib2=I
sM...(7) becomes. Here, Ipa2 is engineering Pa2=ISb2 −・−・(8
).

Ial@Ia2eIY=IX-Ib2- Ibx
−・Only when (9) holds and equation (8) holds (
(Input) The circuit shown in the figure is the operating area.

And when I p a 2 =) I s b 2, (9
) For the formula to hold, I a 1 = I X = O or Ib] = Iy = O-
...(10) occurs.

Such characteristics can be expressed graphically as shown in Figure (B). (B) The vertical axis of the figure is the current IPX at terminals Px and Py,
IPY is shown, and the horizontal axis is the current value Ipa2 at terminal Pa2.
It shows. Ipx=Ia]=l.

Since Ipy=Ibx=Iy, Ipa2=Isbz
When Ipx and Ipy are equal to each other (EJo/2
) Presentation.

When the condition of Ipaz=Idayb2 is removed, one of the transistors Qx and QY of the differential amplifier instantly becomes conductive and the other becomes cutoff, according to equation (10). Therefore, this means that the states of IPX and IPY switch at Ipaz=IsM.

This is due to the following operation.

For example, when the '1 current Iy of the transistor Qy tries to increase, the current Ib1 of the transistor Qb1 increases by t,
Qbx emitter 4th place goes down. (On the contrary, transistor Q
The current Ix of x decreases to 5). When the emitter potential of Qbl decreases, the base potential of the transistor Qx decreases via the emitter follower transistor Qb2, the current Ix of Qx decreases, and the current Iy of Qy tries to further increase. The decrease in Ix is the current Ia of transistor Qal]
decreases and increases the emitter potential of Qal, which in turn increases Qa
Raise the emitter potential of z, raise the base potential of QY, and
Promotes an increase in y and a decrease in Ix.

Theoretically, such an increase in Iy and a decrease in Ix occur instantaneously, but in reality, the characteristics have a steep slope as shown in the diagram (B).

The area where bζ is switched (near Ipaz=Isb2) becomes a high gain circuit, which is extremely advantageous for amplifying a minute signal, converting a sine wave into a rectangular wave, or using an equal pressure signal discrimination circuit.

FIG. 2 shows another embodiment of the present invention, which is a differential input circuit. FIG. 2(A) shows a specific circuit, and FIG. 2(B) shows a characteristic diagram.

In Figure 2, the transistor corresponding to Qx in Figure 1 is connected to QXI, the parallel transistor QK2 and 1, the collector of QXI is connected to the emitter of Qa, the collector of Q10 is connected to the emitter of Q+), and the collector of Q10 is connected to the emitter of Q Qbz the collector of
is connected to the collector of Furthermore, connect the collector of Qa] and the collector of Qbx to make the output 4Px, and then
The collector of z is set as the output iPY. And Q22.
The emitters of Qbl are respectively connected to current supply terminals Pa2. Pb
Connected to 1.

Further, the emitter of Qaz is grounded via a current source l5az.

From Figure 8g2 (A).

Furthermore, Ia Yu・Ia2−IY=IX−Ib2−IPI
--(12)(11), From formula (12), IPX=2IX]=2(IPa2-IPbl-)-IS
a2) --(13) Ipy=Iso-Ipx
−・−(14).

Now, if l5O=4IBa2, (13), (1
4) The %4 degree property of the formula is as shown in Figure 2 (B),
An output proportional to the differential input between Ipaz and lPb1 can be linearly extracted.

2. The present invention is not limited to the illustrated circuit, and various modifications may be made. For example, Qaz and Qbz can be replaced with diode junctions that have the same base-emitter junction characteristics as a transistor, and the junction circuit can be replaced with a two-stage series connection (
Qal, Qaz).

(Qbx, Qbz) It is also possible to configure the number of stages other than K.

〔Effect of the invention〕

As described above, the circuit of the present invention can obtain linear characteristics,
It also allows the creation of high-gain switching circuits, and has a wide range of applications, including amplification of minute signals and waveform shaping.

Moreover, it is suitable for semiconductor integration, is stable against temperature and element fluctuations, and is advantageous in reducing voltage because it is in a single current mode. In addition, it is possible to perform minute current operation and reduce power consumption, etc. -b-
be.

[Brief explanation of drawings]

FIGS. 1 and 2 are circuit diagrams and characteristic diagrams showing respective embodiments of the current conversion circuit of the present invention, and FIG. 3 is a circuit diagram showing a conventional current conversion circuit. Qx, QR... Transistors forming a differential amplifier. Pa2. Ph] ・・Input hawk flow supply Mizuko. Px, Py... Output terminal. Agent Patent Attorney Noriyuki Chika Yudo Hiroshi Uji (A+ +5n (II) Figure 1

Claims (2)

[Claims] (1) The first one whose emitter is commonly connected to the reference current terminal,
A differential amplifier including a second transistor, and m semiconductor junctions (m≧1) each formed by a base-emitter junction of a transistor or a diode junction having the same base-emitter junction characteristics, m>1. In the case of , they are connected in series, and at least each first stage consists of the base-emitter junction of a transistor
first and second junction circuits in which the base of the first stage transistor is connected to a bias power supply, and the output end of each final stage is connected to the bases of the first and second transistors, respectively; A collector is connected to an output terminal of a semiconductor junction of one of the second junction circuits, and a collector of the second transistor is connected to an output terminal of a semiconductor junction of one of the first junction circuits. connection means comprising a line; input current supply means connected to the output ends of arbitrary semiconductor junctions of the first and second junction circuits; and an output from the line connected to the collectors of the first and second transistors. A current conversion circuit comprising means for extracting the current. (2) In addition to the first and second transistors, the differential amplifier includes a third transistor whose emitters are commonly connected to the emitters of these transistors and whose bases are commonly connected to the base of the second transistor. and the connecting means includes a line connecting the collector of the third transistor to the output end of one of the semiconductor junctions of the second junction circuit. The current conversion circuit according to item 1.