JPS596606A - Method for calculating ratio - Google Patents

Abstract

PURPOSE:To reduce the number of current controlling elements even if a set current ratio is a large value by constituting plural current mirror circuits so that copying current from one current mirror circuit is used as input current for the succeeding current mirror circuit. CONSTITUTION:In a current mirror circuit CP-1, the terminal 1G of an element group 1-1 is connected with the terminals 2G, 2D of an element group 2-1 and the same voltage is applied to the terminals 1G, 2G. Current i3 flowing into the element group 1-1 is controlled by the current i2 flowing into the element group 2-1. Namely, the element group 2-1 is used as a control circuit and the element group 1-1 is used as a copying circuit to copy the current i2 at a prescribed ratio. Since the current mirror circuits CP-2, CN-1, CN-2 have the same terminal connection, the element groups 2-2, 4-1, 4-2 are acted as control circuits respectively and element groups 1-2, 3-1, 3-2 are acted as copying circuits respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ratio calculation method that multiplies or divides an input analog signal by a predetermined ratio and outputs the result.

Conventionally, when input analog signals are multiplied (or divided) by a predetermined ratio and output, 1: For example, 1:n (n is any number)
'l! A current mirror circuit was used. In this case, the current mirror circuit used is one in which one circuit is composed of one transistor and the other circuit is composed of a transistor with a junction area n times that of this transistor. Consists of one current control element (transistor, etc.), and the other circuit
There was one that consisted of several current control elements. However, such current mirror circuits have a drawback in that it is not possible to achieve accurate 1:n staining due to the influence of characteristic deviations of the current control elements constituting one and the other circuit.

Further, when the value of n becomes, for example, about 10.000, a problem arises in that the number of current control elements forming the Cullen Bler circuit increases.

A drawback has arisen in that variations in the characteristics of one current control element constituting one circuit have a large effect on the current ratio.

In view of the above-mentioned circumstances, the present invention allows the ratio to be unaffected by variations in the characteristics of the current control element.

This provides a ratio calculation method that requires a small number of current control elements even if the ratio becomes a large value. The current mirror circuit that outputs the copied current and the current mirror circuit to which the copied IrL flow is connected to each other are constructed so that the copied current of each current mirror circuit becomes the input current of the next current mirror circuit in sequence, and the current mirror circuit that outputs the copied current and the current mirror circuit that is supplied with this copied IrL flow are It is composed of reverse conductive DC control elements.

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

FIG. 1 is a block diagram showing the configuration of a first embodiment 511 of the present invention.

In this figure trap, C-1, Cp-2, CN-1゜CN-2
are current mirror circuits, and c-1, c, and -2 are respectively shown in Figure 2, and CN-1 and CN-2 are each constructed as shown in Figure 3. In Figure 2, 1
is a p-channel FET ([field effect transistor Qa-1 to Qa-c, hereinafter referred to as element group],
FET is broken. )2 is p-channel FET qb
It is an element group consisting of -1 to Qb-1000.
The gates of FETQ-1 to Q-1000 are b
b Terminal 2G, source to terminal 28, drain to terminal Q
When the gate forces of b-1 to Q5-1000 are made equal and the terminal IS and 2SIC current are supplied, FETQa-1 to Q
Since the same current flows through each of a-100 and Qb-1 to Qb-1000, la flowing through element group 1 and element group 2
The ratio of the current l flowing through the element groups 1 and 2 is the ratio of the number of elements (10
0:10000), which is equal to 1:10. , In Fig. 3, 3 is an N-channel FET Q, -1 to Q, -
It is an element group consisting of 100 IT Qo-
The gates of 1 to Q-100 are connected to terminal 3G, and the sources are connected to terminal 3.
S and the drain are connected to the terminal 3D, respectively. 4 is N-channel FET Qd-1 to Qd-1000
An element group consisting of .

The gates of the FETs Qd-1 to Qd-xooo are connected to the terminal 4G, the sources to the terminal 4S, and the drains to the terminal 4D. In this case, terminal 3G.

4 G'&Fi'ii rank Nishite, terminal 3D, 4DKW
If current is supplied, the ratio of the current 1c flowing through element group 3 to the current 1d flowing through element group 4 is equal to the ratio of the number of elements between element groups 3 and 4 (100:1000), which is 1:
It becomes 10.

Now, the current mirror circuit C9-1 in the tJLi diagram
is terminal IG of element group 1-1 and terminal 2G of element group 2-1.
, 2D are connected so that the same voltage is supplied to the % terminals IG and 2G. Also, in this case, since the gates and drains of each of the FETs Qb-1 to Qb-1oooo in the element group 2-1 are connected -C, a current of 12V flows through the element group 2-1. Current 13 (
x3/□0·t2) is controlled. In other words, “$
The group A-1 serves as a control side circuit, and the element group 1-1 serves as a copying circuit that copies a current 1□ at a predetermined ratio C1/10'. Also, a current mirror circuit Cp-2.

CN-1 and CN-2 are also current mirror circuits Cp-1
Since the terminal connection is similar to that of element group 2-2.4
-1.4-2 are control side circuits, and element group 1-2.
3-1 and 3-2 are respectively called copy side circuits. zl
is an impedance element %z2 is a variable impedance element, and one end of impedance element z1,
Positive power supply +E to terminals 18 and 28 of current mirror circuit cp-2 and terminals 1s and 2s of current mirror circuit %C-1.
is supplied, and the current mirror circuit ON −
A negative power supply -E is supplied to the terminals 38 and 48 of the current mirror circuit @CH-1 and one end of the variable impedance element z2.

In the circuit described above, since the gate-source voltage of the element group 2-1 is determined by the impedance of the variable impedance element z2, the flow 1□ is determined by the impedance of the variable impedance element z2. Then, the current 13 flowing through the element group 1-1→4-1 is 1=(1/1o)・12, as can be seen from the above, and the current l flowing through the element group 2-2→3-1 is 1- (”
/10)-1344-. Similarly, t = (1/1°)・14°1, = (1
/, o)・15. That is, the currents 1□ and 1
The relationship between 2 and 2 is shown by the following equation.

1 1 1 11 l"
l 2° (w) ° [-H)° (-;)
) expression as current mirror circuit cp-1, cp-2゜CN-
1, expressed as the element number ratio of CN-2, 100
100 10011=12° (°plane '
1000” '1000'.

00 (-1−−−−−−−−−−−−−−−−+21000 becomes.

In this case, the current ratio 11:1□=1:10000 is 1
If the current mirror circuit is to be used, at least 100 current control elements are required, but in this embodiment, as can be seen from equation (2), 4400 current control elements are sufficient. Moreover, in each current mirror circuit, both the control side circuit and the copying side circuit are composed of multiple current control elements, so variations in the characteristics of the individual current control elements are canceled out and extremely accurate. It is possible to obtain a current ratio of

FIG. 4 is a block diagram showing the configuration of a second embodiment of the invention. In this figure, the same reference numerals are given to the parts corresponding to those in FIG. 1, and the explanation thereof will be omitted.

The current mirror circuit CN-2 in this figure is the element group 3.
Since terminals 3G and 3D of -2 are connected to terminal 4G of element group 4-2, wL flow 1□ flowing through element group 3-2
Current t5 flowing through element group 4-2 due to V (15=1
0 X tl) is controlled. That is, element group 3
-2 is the control side circuit, and the element group 4-2 has a current of 11
The reproduction side circuit reproduces the image at a predetermined ratio (10 times). In addition, current mirror circuits CP-2, CN-1, C
, -1 have the same terminal connections as the current filter circuit cN-2, so element group 1-2.3-1.1-1 each becomes a control side circuit, and element group 2-2.4- 1.2-1 are copy side circuits. io is a variable impedance element and hZ2 is an impedance element.

In the circuit described above, since the gate-source voltage of the element group 3-2 is determined by the impedance of the variable impedance z'1, the current 1□ is ultimately determined by the impedance of the variable impedance element zl. And the current 15 is 11×10.14 is '5×'' h ia is i4X 10.12 is 13X10. Therefore,
The relationship between 11 and 1□ in this example is expressed by the following equation.

iz= tlx 10 x 10 x 10 x 10
-----------(31) Thus, this embodiment has the function of step-amplifying the current 11.

In addition, if this embodiment is to be a voltage input type.

For example, as shown in FIG. In this figure, reference numeral 10 denotes an amplifier, which amplifies the voltage etn supplied via the input resistor Rin and sends the output voltage to the terminal 3 of the element group 3-2.
G and the terminal 4G of the element group 4-2. Further, the input terminal of the amplifier 10 and the terminal 3D of the element group 3-2 are connected. According to such a configuration, since the current 11 is determined by the output voltage of the amplifier 10, that is, the voltage sin, the current 1□ is controlled by the input voltage ein.

FIG. 6 is a block diagram showing the configuration of a third embodiment of the invention. Note that this embodiment is an example in which the present invention is applied to a two-wire transmitter.

In this figure, 21 is a constant voltage circuit that outputs a constant voltage vc0, 20 is an operational amplifier, Ra is a variable resistor that divides the voltage ■cc and supplies it to the inverting input terminal of the operational amplifier 20, and 24 is driven by the operational amplifier 20. output transistor. Further, 22 is a power supply, 23 is a load,
These are located at remote receivers.

In the circuit shown in this figure, current mirror circuit CN
-1, C, -2, CN -2 operate in the same way as in the first embodiment described above.

In the circuit described above, when the input voltage 61n (voltage supplied from a sensor circuit not shown) rises, the output voltage of the operational amplifier 20 rises, and the current 1s flowing through the element group 3-2 causes the output transistor 24 to rise. The flowing current increases by 1°. As a result, the copy current 1 increases, the voltage division ratio between the resistor Rin and the element group 3-2 changes, and the potential at the non-inverting input terminal of the operational amplifier 20 decreases. In this way, the operational amplifier 20 adjusts its output voltage so that the voltage difference between both input terminals is zero. Note that the input voltage el
When n decreases, the same operation as in the above case occurs.

In this way, in this embodiment, the output voltage of the operational amplifier 20 is determined by the input voltage 61n, and this output voltage determines l. is determined.

That is, current 1° corresponds to input voltage amount β.

Figure s1!7 is a block diagram showing the configuration of a fourth embodiment of the present invention. In this figure, parts corresponding to those in FIG. 1 are given the same reference numerals.

According to the circuit shown in this figure, the current mirror circuit CN −
When the circuit is not operating by 3%, the current 14b does not flow, so 14==14a, and this circuit becomes approximately the same as the circuit shown in FIG. Therefore, current 1 →i
-41 (=i4) → 15 → 1□ order 2 3
4a, the step is sequentially stepped down at a predetermined ratio. On the other hand, when the current mirror rotation %CN-3 is activated, the current '4b is controlled by the current 16.

In this case, the current becomes '4a-'4-'4b, so the current mirror circuit CN+42, Cp-2 has a C amount of 4-
14b) is sequentially stepped down at a predetermined ratio. Thus, in this real IIfA example, the 4
4b Can perform calculations.

As explained above, according to the present invention, one circuit and the other circuit are each composed of a plurality of current control elements, and the ratio of the currents flowing through each circuit is the ratio of the number of current control elements constituting each circuit. A plurality of current mirror circuits are provided, and each of the plurality of current mirror circuits is configured to be a copy 1x of one current mirror circuit, and the current is configured to sequentially become the input current of the next current mirror circuit, and the copy current is output. Since the current mirror circuit to which the current mirror circuit is applied and the current mirror circuit to which this copied current is supplied are constructed with current control elements having conductivity opposite to each other, the current ratio can be set accurately without being affected by variations in the characteristics of the current control elements. Moreover, even when the set current ratio becomes a large value, there is an advantage that the number of current control elements can be reduced.

[Brief explanation of the drawing]

Figure 2 is a block diagram showing the configuration of the first embodiment of the present invention, Figure 2 is a circuit diagram showing the configuration of the current mirror circuits C, CN shown in Figure 1, and Figure 84 is a circuit diagram showing the configuration of the current mirror circuits C, CN shown in Figure 1. The vXS diagram is a block diagram showing the configuration of the 1s2 embodiment of the invention, the vXS diagram is a block diagram showing the configuration when the same embodiment is made into a voltage input type, and FIG. 6 is a block diagram showing the configuration of the IE3 embodiment of the invention. , FIG. 7 is a block diagram showing the configuration of a fourth embodiment of the present invention. CN-1 to CN-a, CP-1 to cp-2... current mirror circuit, Q&-1 to Q&-100. Qb-1 to Qb-1000...p channel FET
(Current control element), Q-1 to Qc-100, Qd-
1~Q, -1000... N-channel FET (current control element 3゜Fig. 1 Fig. 2/Blood

Claims (1)

[Claims] One circuit and the other circuit each include a plurality of current control elements, and a plurality of current mirror circuits are provided in which the ratio of the currents flowing through each circuit is the ratio of the number of current control elements constituting each circuit, The current mirror circuit is configured such that the copied current of one current mirror circuit becomes the input current of the next current mirror circuit in sequence, and the current mirror circuit outputs the copied current and the current mirror to which the copied current is supplied. A ratio calculation method characterized in that the circuit is composed of current control elements having conductivity opposite to each other.