JPH1093436A - Digital/analog conversion circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output an accurate analog signal by connecting plural current source to this current control circuit so as to control digital/analog conversion characteristic by current set information so as to execute nonlinear digital/ analog signal conversion. SOLUTION: A current control circuit 13A is connected with the current sources 121 to 123 and outputs a current according to the content of a current setting signal CSA to input. Similarly, a current control circuit 13B is connected with the current sources 124 to 126 and outputs a current according to the content of a current setting signal CSB to input. Then the current sources 121 to 126 are provided with a current expressed by plural coefficients and convert a digital signal DI to plural nonlinear analog output AOUT according to the contents of the signals CSA and CSB to output. By supplying current setting information and controlling the characteristic of conversion from a digital signal to an analog signal like this, nonlinear digital/analog signal conversion is executed. In addition an accurate analog signal is output without omitting information originally provided for the digital signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital-to-analog conversion circuit, for example, to a digital-to-analog conversion circuit used for converting digital image data into an analog signal.

[0002]

2. Description of the Related Art Along with recent advances in digital signal processing technology, various devices have been replaced with those using digital signals from those using analog signals.
However, since human vision and hearing discriminate the amount of analog, it can be said that there is no device that uses only digital signals, even devices where most processing is performed by digital signals, In any part, conversion from an analog signal to a digital signal and from a digital signal to an analog signal are performed.

As a circuit for performing such signal conversion,
Circuits of various configurations are known. For example, a circuit having the configuration shown in FIG. 7 is known as a digital-to-analog conversion circuit that converts a digital signal into an analog signal.

This digital / analog conversion circuit has three
Circuit for converting digital signal DI of the unit into an analog signal
As shown, the decoder 51 and the seven current sources
52 ₁~ 52₇It is composed of

[0005] The decoder 51 is a circuit that outputs output control signals OE _{1 to} OE ₇ corresponding to the contents of the input digital signal DI. When the decimal value of the digital signal DI is m (m = 0 to 7), the decoder 51 outputs a signal corresponding to the truth value “1” as the output control signal OE _i (i ≦ m). , As an output control signal OEj (j> m),
A signal corresponding to the truth value "0" is output.

The current sources 52 _{1 to} 52 ₇ have the function of outputting currents I ₁ of the same magnitude. Each current source 52 _k (k = 1 to
7), the output control signal OE _k from the decoder 51 is input, and the current source 52 _k is turned on when the output control signal OE _k corresponding to “1” is input, outputs a current I _1. As is shown, the current output of the current source 52 ₁ to 52 ₇ are connected in parallel, the digital-analog conversion circuit, the sum of the currents of all of the current source 52 is outputted as an analog output A _OUT Output.

That is, in this digital / analog conversion circuit, the decoder circuit 51 outputs the output control signals OE _{1 to} OE ₇ for turning on the current sources 52 of the number corresponding to the value of the digital signal DI. I do. Each current source 52, when it becomes "ON" state, so output the same current I _1, as shown in FIG. 8, from the digital-analog converter circuit is proportional to the digital signal DI An analog output A _OUT having a magnitude is output.

[0008]

As the digital-to-analog conversion circuit, various circuits having different configurations (operating principles) are known in addition to the above-described digital-to-analog conversion circuit. However, conventional digital / analog conversion circuits are all circuits in which conversion characteristics (correspondence relationship between input and output) are fixed. For this reason, when a conventional digital / analog conversion circuit is used, a problem in conversion accuracy may occur depending on the field of use.

For example, consider the case where a conventional digital-to-analog conversion circuit is used to generate an analog signal used as an input signal of a display device such as a CRT (cathod ray tube) from digital image data. In this case, since the correspondence between the input voltage of the display device and the luminance of the image displayed with respect to the input voltage is non-linear, an image that accurately corresponds to the digital image data is displayed. In order to perform the display, it is necessary to perform some kind of correction on the display device side or on the device side having the digital / analog conversion circuit. When this correction is performed on the digital / analog conversion circuit side, in practice, some digital data having different values (gradation information) are converted into analog signals having the same magnitude. Digital-to-digital conversion must be performed. When such a correction is performed, the digital image data and the luminance can be better associated with each other as compared with a case where the correction is not performed. Part of the key information will be lost. Further, when the display device to be connected is changed, the display characteristics of the display device itself change, so that the conversion characteristics at the time of digital-to-digital conversion must be reset.

The present invention has been made to solve such a problem, and has as its object to provide a digital-to-analog conversion circuit capable of controlling the conversion characteristics of a digital signal into an analog signal. I do.

[0011]

A digital-to-analog conversion circuit according to the present invention comprises a first predetermined number of current output means capable of setting a current value of a current to be output and controlling whether or not to output a current. Output control means for selecting some current output means corresponding to the input digital signal from among the first predetermined number of current output means, and outputting a current to each of the selected current output means; An analog signal output means for outputting an analog signal having a magnitude corresponding to a value obtained by adding the current values of the currents output by the current output means;
Each of the predetermined number of current output means receives input of setting information which is information for determining a current value of a current to be output, and outputs each current output means such that a current of a current value determined by the setting information is output. And current value control means for controlling the current value.

That is, according to the present invention, a plurality (first predetermined number) of current output means capable of controlling on / off of current output are provided.
When configuring a digital-to-analog conversion circuit of the type that controls according to the digital signal to be converted to an analog signal and outputs an analog signal corresponding to the sum of the current outputs of all the current output means, the current output means , While using means capable of setting the current value of the output current,
In the digital / analog conversion circuit, current value control means for controlling each current output means is provided so that the current value of the current output from each current output means corresponds to the setting information supplied from the outside. .

As described above, the present digital / analog conversion circuit can control the conversion characteristic of a digital signal into an analog signal by changing the content of the setting information to be supplied. In addition, since it is possible to have a non-linear conversion characteristic, for example, if a device that generates an analog signal for a display device such as a CRT from digital image data is formed using the digital-analog conversion circuit, It is possible to obtain a device that can output an analog signal exactly corresponding to information originally contained in digital image data without losing the gradation information originally contained in the digital image data. In addition, the device is a device capable of controlling the conversion characteristics, so that it is possible to easily cope with a change in the target display device.

When configuring the digital-to-analog conversion circuit of the present invention, a first predetermined number of current output means are provided.
Each of the current control means is classified into a second predetermined number of groups that is less than the first predetermined number, and the same control signal is supplied to current output means classified into each of the second predetermined number of groups. It is also possible to employ a current value control means for controlling the first predetermined number of current output means so that the current output means outputs a current having a current value determined by the setting information.

When such a configuration is adopted, the current value control means can be realized by a simple circuit, so that a digital-to-analog conversion circuit whose conversion characteristics can be controlled with a small number of elements can be formed.

In configuring the digital-to-analog conversion circuit of the present invention, each of the first predetermined number of current output means receives input of setting information for determining a ratio of a current value of a current to be output, and receives each current. The first predetermined number of currents are output so that the current value of the current output from the output means has a ratio determined by the setting information, and the sum of the current values output from all the current output means is a predetermined value. Current value control means for controlling the output means may be employed.

In the digital / analog conversion circuit configured as described above, when the conversion characteristics are controlled (change of the setting information to be supplied), the full scale of the analog signal becomes
It is automatically controlled to be constant. Therefore, when the digital-to-analog conversion circuit is configured by employing the current value control means as described above, the digital-to-analog conversion circuit does not need to separately perform full-scale adjustment even if the conversion characteristics are changed. Is obtained.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. <First Embodiment> The digital-to-analog conversion circuit of the first embodiment is a circuit that converts a 3-bit digital signal into an analog signal.

FIG. 1 shows a schematic configuration of a digital-to-analog conversion circuit according to the first embodiment. As shown, a digital-analog converter circuit includes a decoder 11, and seven current sources 12 ₁ to 12 _7, and a two current control circuit 13 _A, 13 _B.

The decoder 11 is a circuit that outputs output control signals OE _{1 to} OE ₇ corresponding to the contents of the input digital signal DI. When the decimal value of the digital signal DI is m (m = 0 to 7), the decoder 11 outputs a signal corresponding to the truth value “1” as the output control signal OE _i (i ≦ m). , As an output control signal OEj (j> m),
A signal corresponding to the truth value "0" is output.

The current sources 12 _{1 to} 12 ₇ are circuits whose current output is turned on / off by output control signals OE _{1 to} OE ₇ from the decoder 11, respectively.
2 _k (k = 1 to 7) is turned on when the output control signal OE _k corresponding to the truth value “1” is input. As is shown, the current output of the current source 12 ₁ to 12 ₇ are connected in parallel, the sum of the currents of all of the current sources 12 ₁ to 12 ₇ outputs are outputted as the analog output A _OUT.

The current control circuit 13 _X (X = A, B) controls the current value output from each current source 12 to a value corresponding to a current setting signal CS _X supplied from the outside. It is. As shown, one current control circuit 1
3 _A is connected to the current source 12 ₁ to 12 _3, in charge of control of these three current sources 12. The other of the current control circuit 13 _B is responsible for control of the remaining four current sources 12 _{4-12 7.} Although details will be described later, each current control circuit 13 _X has a current setting signal CS _X as
The setting signals S _{X1 to} S _X3 which are binary level signals are input.

Hereinafter, the configuration and operation of the digital-to-analog conversion circuit will be specifically described with reference to a circuit diagram (FIG. 2). The current control circuit 13 _A, 13 _B is the same circuit configuration, the current source 12 ₁ to 12 ₇ are also the same circuit configuration, FIG. 2, the current control circuit 13 _A and the current source 12 ₁ 1 is only shown.

As shown, the current control circuit 13 _A
Six P-channel MOS transistors 21 to 26,
It comprises a constant current source 30 that outputs a constant current I ₀ . The current source 12 _1, two P-channel type MO
It is constituted by S transistors 27 and 28. The MOS transistors 21, 22, 23 and 27 are formed so that their channel lengths are equal.

The source of the MOS transistor 21 to 23 of the current control circuit 13 _A is connected to the power supply line 41, the drain of the MOS transistor 21 to 23, respectively, are connected to the source of the MOS transistor 24 - 26 I have. The gates of the MOS transistors 21 to 23 are connected to the control signal line 42. The control signal line 42 is also connected to the drains of the MOS transistors 24 to 26, the constant current source 30, and the gate of the MOS transistor 27 in the current source 12. Then, the gate of the MOS transistor 24 to 26, respectively, set signals S _A1, S _A2, S _A3 is an element of the current setting signal CS _A is inputted.

Current source 12₁MOS transistors that compose
The source of the heater 27 is connected to the power supply line 41,
IN is connected to the source of the MOS transistor 28
I have. The gate of the MOS transistor 28 has a decoder
Output control signal OE from 11 ₁Is entered and MO
The drain of the S transistor 28 is connected to the analog output A_OUT
Is connected to a signal line 43 for extracting the data.

The MOS transistors 21 to 23 and the MOS transistor 27 are designed to operate in a saturation region. As shown in the figure, since the gate and the source of each MOS transistor are connected to the same potential, the portion composed of these MOS transistors operates as a current mirror. Further, the MOS transistors 21 to 23, respectively, the MOS transistors 24 to 27 which functions as a switch are connected in series by MOS transistors of the combination in accordance with the contents of the current setting signal CS _A, the current mirror Will be composed.

For example, the current setting signal CS_AIs a MOS transistor
A signal S for controlling only the transistor 24 to the "on" state_A1
Is satisfied, the MOS transistor 24 and the MOS transistor
A current mirror is formed by the transistor 27.
You. Therefore, in this situation, the current source 12₁MOS tiger inside
The output control signal OE of "1" level is supplied to the transistor 28.₁Enters
When energized, the current source 12₁To the signal line 43
_CASE1= (W₂₇/ W_{twenty one}) ・ I ₀The size of which is represented by
A stream is provided. In the above relational expression, W₂₇, W
_{twenty one}Are the effective values of the MOS transistors 27 and 21, respectively.
Channel width.

Similarly, the current setting signal CS_AIs a MOS transistor
Turn on the transistor 24 and the MOS transistor 25
State control signal S_A1And S_A2MOS
The output control signal OE of "1" level is supplied to the transistor 28.₁
Is input, the current source 12₁From the signal line 43
And I_CASE2= (W₂₇/ (W_{twenty one}+ W_{twenty two})) ・ I₀In that big
A current representing the magnitude is supplied. Also, the current setting signal
CS_ABut all three MOS transistors 24-26
Signal S for controlling to "ON" state_A1~ S_A3If
Is the current source 12₁To the signal line 43_CASE3= (W₂₇/
(W_{twenty one}+ W_{twenty two}+ W _{twenty three})) ・ I₀The current represented by
Will be. Where W_{twenty two}, W_{twenty three}Is M
The effective channel width of the OS transistors 22 and 23.

[0030] As described with reference to FIG. 1, the current control circuit 13 _A is also connected to a current source 12 ₂ and the current source 12 _3. Thus, current source 12 ₂ and the current source 12 ₃ also outputs a current corresponding to the contents of the current setting signal CS _A being input to the current control circuit 13 _A. That is, the current control circuit 1
Three 3 connected to the _A of the current source 12 ₁ to 12 ₃ outputs a current having the same current value.

[0031] The operation of the current source 12 _{4-12 7} also, the current source 12
_The current sources 12 ₄ to 12 ₃ are the same as _{1 to} 12 _3.
7, when turned on, corresponding to the contents of the current setting signal CS _B supplied to the current control circuit 13 _B, and outputs the current having the same current value.

[0032] Thus, the current source 12 ₁ to 12 ₃ of the digital-to-analog converter in the circuit outputs a level of current in accordance with the contents of the current setting signal CS _A, the current source 12 _{4-12 7}
Outputs the level of the current in accordance with the contents of the current setting signal CS _B. Therefore, the current that current source 12 ₁ to 12 ₃ are respectively output expressed in k ₁ I _0, if the current current source 12 _{4-12 7} outputs respectively, expressed in k ₂ I _0, the digital signal DI The relationship shown in FIG. 3 is established between and the analog output A _OUT . Note that k ₁ and k ₂ are W ₂₇ / W ₂₁ , W ₂₇ / (W ₂₁ + W ₂₂ ), W ₂₇ / (W ₂₁ +
W ₂₂ + W ₂₃ ). For example,
During the effective channel _{width, W 27 = 1.5 · W 2} 1, W 22 = 0.5 ·
If a relationship such as W ₂₁ , W ₂₃ = 1.5 · W ₂₁ is set, k ₁ and k ₂ take one of 1.5, 1.0 and 0.5.

As shown in FIG. 3, in the present digital / analog conversion circuit, when DI is 3 or less, A
_OUT = DI × k ₁ I ₀ is taken and the DI was 4 or _{more, A O UT = (DI-} 3) × k 2 I 0 + 3k 1 I 0 is established. That is, when the current setting signals CS _A and CS _B are selected so that k ₁ and k ₂ have different values, the digital-to-analog conversion circuit includes two lines as illustrated in FIG. It functions as a digital-to-analog conversion circuit showing the conversion characteristic represented by the broken line composed of the segments. Also,
Since each of k ₁ and k ₂ is a value that can be selected from three types of values, this digital-to-analog conversion circuit includes five types of non-linear conversion characteristics in addition to the conversion characteristics shown in FIG.
This is a circuit that can be operated as a circuit that exhibits various linear conversion characteristics.

As described above, the digital-to-analog conversion circuit according to the first embodiment is configured so that a conversion characteristic to be used in actual digital-to-analog conversion can be selected from a plurality of conversion characteristics. Since it is possible to operate as a circuit having the conversion characteristics of the above, if a device that generates an analog signal to be input to the display device is formed using this digital / analog conversion circuit, the digital image to be converted can be converted. The information contained in the data can be displayed on the display device without losing the information. Further, even when the required conversion characteristic changes due to the change of the display device, it is possible to easily cope with the change.

<Second Embodiment> FIG. 5 shows the overall configuration of a digital-to-analog conversion circuit according to a second embodiment. As shown, a digital-analog converter circuit of the second embodiment, the decoder 11, and seven current sources 12 ₁ to 12 _7, 2
Current monitor circuits 14 _A and 14 _B and the total current control circuit 1
5, and a two current control circuit 16 _A, 16 _B. Of these components, the decoder 11 and the current source 12 ₁ to 12 _7, a decoder 11 for digital-to-analog converter circuit of the first embodiment is provided, a circuit of the current source 12 ₁ to 12 ₇ of the same configuration, FIG. As is apparent from the above description, the digital-to-analog conversion circuit according to the second embodiment is substantially the same as the digital-to-analog conversion circuit according to the first embodiment except that current monitoring circuits 14 _A and 14 _B and a total current control circuit 15 are added. It is a circuit.

Hereinafter, the digital / analog analysis will be described with reference to FIG.
The configuration and operation of the analog conversion circuit will be described in detail. Note that the current
Monitor circuit 14_A, 14_BAre almost identical circuits.
Current source 12₁~ 12₇Is a circuit with exactly the same configuration
Therefore, FIG. ₁And current monitor circuit 14_AWhen
All current control circuit 15 and current control circuit 16_ACircuit configuration
Is shown. Also in this embodiment, each M
OS transistor channel lengths are set equal.
You.

As shown, the current control circuit 16 _A
Instead of the current control circuit 13 _A of the constant current source 30 (see FIG. 2), it has a circuit in which a n-channel type MOS transistor 31.

The current monitoring circuit 14 _A, the effective channel width W ₃₂ is the source and gate of the MOS transistor 32 which is set to 0.3 times the effective channel width W ₂₇ of the MOS transistor 27 of the current source 12 _1, respectively, It is formed by connecting to a power supply line 41 and a signal line 42. That, MOS transistor 32 in the current monitoring circuit 14 _A, as its drain current becomes 1/10 of the sum of the drain currents of the three MOS transistors 27 provided in the current source 12 ₁ to 12 ₃ , (relative to the current source 12 ₁ to 12 ₃₎ to the power supply line 41 and signal line 42 is connected. Then, the drain current of the MOS transistor 32 is used as the monitor output _MOA as the total current control circuit 1.
5.

[0039] Although not shown in FIG. 6, the current monitor circuit 14 _B also has a circuit having the same configuration. However, the current monitoring circuit 14 _B, the number of current source 12 different from the current monitoring circuit 14 _A is connected, as the MOS transistor 32 of the current monitor circuit 14 in the _B, the effective channel width W, MOS transistor A transistor set to 0.4 times the effective channel width W ₂₇ of ₂₇ is used. That is, the current monitor circuit 14 _B
2 ₄ 1/10 of the sum of the drain currents of the 12 four provided in the ₇ MOS transistor 27, a monitor output M
It is configured to output as _OB .

The total current control circuit 15 includes a resistor 33 having a resistance value R ₁ and a differential amplifier 34.
The non-inverting input terminal of the differential amplifier 34, is inputted reference voltage V _R is to the inverting input terminal, as is apparent from the figure, the resistor 33, and a monitor output M _OA which is converted into a voltage signal the sum of the monitor output M _OB is input. The output of the differential amplifier 34 is inputted to the gate of the MOS transistor 31 of the current control circuit 16 _A.

[0041] In digital-analog converter circuit of the second embodiment having such a configuration, the sum of the monitor output M _OA and the monitor output M _OB is, V _R / R ₁ is greater than the inverting input of the differential amplifier 34 The input voltage to the terminal is higher than the input voltage to the non-inverting input terminal. Therefore, if the sum of both the monitor output is greater than V _R / R _1, the output voltage of the differential amplifier 34 is lowered, the drain current of the MOS transistor 31 of the current control circuit 16 _A is reduced. MOS transistor 31 is instead apparent as from the fact that is used in the constant current source 30 (see FIG. 2), the drain current of the MOS transistor 31, the current for determining the current value of the current source 12 ₁ to 12 ₃ This is the mirror input current. Therefore, when the drain current of the MOS transistor 31 decreases, the current value output when each current source 12 is turned on decreases. Conversely, monitor output M _OA
And the sum of the monitor output M _OB is smaller than V _R / R ₁ , M
As a result of an increase in the drain current of the OS transistor 31,
The current value output by the current source 12 increases.

That is, in the present digital-analog conversion circuit, the current control circuits 16 _A and 16 _{A are} controlled by the total current control circuit 15 so that the sum of the monitor output _MOA and the monitor output _MOB coincides with V _R / R _{1. B} is controlled. This control is control not depending on the contents of the current setting signals CS _A and CS _B. The monitor output M _OA and monitor output M _OB, respectively, which is 1/10 of the sum of the current value by the current source 12 ₁ to 12 _3, the current source 12 _{4-12 7} outputs. Therefore, in the digital-to-analog conversion circuit according to the second embodiment, when the conversion characteristic is changed, the sum of the current values output by all the current sources 12 is one.
/ 10, to match the V _R / R _1, i.e., the full scale of the analog output A _OUT is to be kept in 10V _R / R _1, so that the current control circuit 16 is controlled . For this reason, the digital-to-analog conversion circuit of the second embodiment is a circuit that does not need to separately perform full-scale adjustment even when controlling (changing) the conversion characteristics.

<Modification> The digital / analog conversion circuit of the embodiment is a circuit in which the output current values of the respective current sources become equal when the same current setting signal is supplied to the two current control circuits. Even if a plurality of current sources that output currents of different magnitudes are used, a digital-to-analog conversion circuit whose conversion characteristics can be controlled can be configured in the same manner as in the embodiment. At that time, some of the plurality of current sources may be current sources that output currents of the same magnitude.

In the digital-to-analog conversion circuit of the embodiment, the current value output from the current source is changed by changing the gate voltage of the MOS transistor. A plurality of MOS transistors, connected in series with them,
A current source that can control the magnitude of the output current value may be configured from a plurality of switches that are turned on and off by the current setting signal.

Further, the number of current control circuits is not limited to two. For example, if N current control circuits are provided, digital control circuits exhibiting a conversion characteristic approximated by a broken line by N line segments are provided. An analog conversion circuit can be configured. Further, it is natural that the number of bits of the digital signal to be converted may be 3 bits or more.

[0046]

As described above in detail, the digital-to-analog conversion circuit of the present invention can control the conversion characteristic of a digital signal into an analog signal by supplying setting information. In addition, nonlinear digital / analog signal conversion can be performed. For this reason, if this digital-analog conversion circuit is used to configure a device for a display device or the like where nonlinear conversion characteristics are desired,
Without losing the information originally contained in the digital signal, it is possible to output an analog signal exactly corresponding to the information originally indicated by the signal. In addition, the device is a device that can easily cope with a change in the target display device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a digital-to-analog conversion circuit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a current control circuit and a current source included in the digital-to-analog conversion circuit of the first embodiment.

FIG. 3 is a diagram illustrating a correspondence relationship between a digital signal input, a control signal, and an analog signal output in the digital-to-analog conversion circuit according to the first embodiment.

FIG. 4 is a diagram illustrating conversion characteristics of the digital-to-analog conversion circuit according to the first embodiment.

FIG. 5 is a schematic configuration diagram of a digital-to-analog conversion circuit according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram of a current control circuit, a current source, a current monitor circuit, and a total current control circuit included in the digital-to-analog conversion circuit according to the second embodiment.

FIG. 7 is a diagram illustrating an example of a conventional digital / analog conversion circuit.

FIG. 8 is a diagram showing conversion characteristics of the digital-to-analog conversion circuit shown in FIG. 7;

[Explanation of symbols]

 11, 51 Decoder 12, 52 Current source 13, 16 Current control circuit 14 Current monitor circuit 15 All current control circuit 21-28, 31, 32 MOS transistor 30 Constant current source 33 Resistance 34 Differential amplifier

Claims (3)

[Claims] 1. A first predetermined number of current output means capable of setting a current value of a current to be output and controlling whether or not to output a current, and the first predetermined number of current output means, Output control means for selecting some current output means corresponding to the input digital signal and outputting current to each of the selected current output means; current of the current output by the first predetermined number of current output means An analog signal output unit that outputs an analog signal having a magnitude corresponding to a value obtained by adding the values; and setting information that is information that determines a current value of a current to be output by each of the first predetermined number of current output units. And a current value control means for controlling each current output means so as to receive an input and output a current having a current value determined by the setting information. 2. The first predetermined number of current output means includes:
The current value control means is configured to output the same control signal to the current output means classified into each of the second predetermined number of groups. 2. The digital output device according to claim 1, wherein the first predetermined number of current output units are controlled so that a current having a current value determined by the setting information is output from each current output unit.・ Analog conversion circuit. 3. The current value control means receives an input of setting information for determining a ratio of a current value of a current to be output by each of the first predetermined number of current output means, and outputs each of the current output means. The first predetermined number of current output means are controlled so that the current value of the current has a ratio determined by the setting information, and the sum of the current values output by all the current output means is a predetermined value. 3. The method according to claim 1, wherein
Digital-to-analog conversion circuit as described.