JPS6348916A - Correcting circuit for error of elemental value - Google Patents

Abstract

PURPOSE:To attain high speed correction by providing an up-down counter between a comparator and a D/A converter constituting a conventional error correction circuit, detecting a voltage generated due to the element error by the comparator, causing a correction value to the counter and inputting the result to the converter. CONSTITUTION:A register of a conventional error correction circuit comprising a comparator, a multiplication D/A converter and a sequential comparison type register placed in between is replaced into an up-down counter 4. Then a switch SZ is opened to bring a potential at a connecting point N1 to 0V, switches SW1, SW2 are used to apply a reference voltage VR to main capacitors C1, C2 to be corrected and auxiliary capacitors CS1, CS2, which are charged up. Then the output is inputted to the comparator 2 and compared with the reference voltage VR, the result is supplied to the up-down counter 4 receiving a clock signal, a generated error signal is fed to the converter 1 to correct the error of the capacitors.

Description

[Detailed Description of the Invention] [Summary] The present invention detects a voltage generated due to an element value error existing between a plurality of elements with a comparator in an element value error correction circuit, and calculates the detection result. is input into an up/down counter to count up or down to generate an element correction value, and the element correction value is input to a multiplication type digital-to-analog converter to select the element value. This makes it possible to generate element correction values at high speed.

[Industrial application field]

The present invention relates to a circuit that corrects element value errors in elements that require high relative accuracy between a plurality of element values.

[Conventional technology]

For example, in an A/D or D/A converter, elements such as multiple capacitors or resistors are essential to perform the conversion, and the values of the multiple capacitors and the multiple resistors are indispensable. Each value in the capacitor requires high relative accuracy. For example, in the case of a capacitor, each capacitance value must be exactly the same or have a certain difference with high accuracy. In addition, the resistance values of the resistors must have the same relationship as in the case of the capacitor.

However, in normal cases, it is difficult to obtain a capacitor or resistor with high relative accuracy as is, so a circuit that corrects errors in element values is used to substantially improve relative accuracy. There is.

FIG. 3 is a block diagram of essential parts for explaining the principle of the element value error correction circuit.

In the figure, 1 and 2 are elements that require high relative accuracy, 3 is an element value comparison circuit, 4 is a control circuit, and 5 and 6
indicate element value adjustment circuits, respectively.

The main operations in this element value error correction circuit will be explained.

The element value comparison circuit 3 compares the values of elements 1 and 2 and sends the comparison result to the control circuit 4. Actually, (value of element 1 + adjustment value) and (value of element 2 + adjustment value) are compared, and the comparison result is sent to the control circuit 4.

The control circuit 4 controls the element value adjustment circuit 5 based on the comparison result.
and 6 to make adjustments? Send Ill command.

The element value adjustment circuits 5 and 6 increase or decrease the capacitance value or the resistance value of the elements 1 and 2.

The above operations are repeated until errors in element values are completely corrected.

Now, conventionally, there are two known specific methods for making +1 positive: a successive approximation method and an integral method.

FIG. 4 is an explanatory diagram of a main part circuit for explaining a capacitance value error correction circuit that implements the successive approximation method.

In the figure, C1 and C2 are main capacitors whose capacitance values should be matched, C31 and C52 are auxiliary capacitors used to match their capacitance values, sz, swl, and SW2 are switches, and R and G are Sui Nochi's (main points) 1 is digital to analog (D/A)
) converter, 2 is a comparator, 3 is a successive approximation register (successive approxim
tion regisLor: 5AR), Nl indicates a connection point, and VR indicates a reference voltage.

In this circuit, the capacitance values of main capacitors C1 and C2 and auxiliary capacitor C3I are fixed, but the capacitance value of auxiliary capacitor C32 appears to increase or decrease due to the action of D/A converter 1. It is now possible to do so.

Next, a case will be described in which capacitance value error correction is performed using this circuit.

First, close the switch SZ and set the potential of the connection point Nl to 0.
[■], and the contact R of the switch SWI is also
The switch SW2 is operated so that the contacts G are respectively closed. As a result, the reference voltage VR is applied to the main capacitor CI and the auxiliary capacitor C31 to accumulate charges, and the main capacitor C2 is grounded.

Next, the switch SZ is opened, and the switch SW1 is operated so that the contact G is closed, and the switch SW2 is operated so that the contact R is closed.

In this case, if CL +C31=C2+C32, the potential at the connection point N1 remains 0 [■
], but if CI +C31≠C2+C32, a voltage VA expressed by the following equation is generated at the connection point N1.

Next, this voltage VA is input to the next comparator 2 and compared with a reference potential, and the result is input to S A R3. Surface and SAR are often used in successive approximation type A/D transformers.

Next, the output of 5AR3 controls D/A converter 1? III
The correction amount is determined by the successive approximation method so that L and voltage VA become 0 [■], and the apparent capacitance value increases or decreases depending on the voltage applied to the auxiliary capacitor C32.

[Problem that the invention seeks to solve]

Generally, when an electronic device is turned on, the temperature continues to rise for a while. In such a case, since variations in element values always occur, it is necessary to correct the element value errors as described above.

However, such element value error correction must be performed in a manner that does not interfere with the normal operation of the electronic device, that is, in between its operations.

In the conventional example explained with reference to FIG. 4, a command for element value error correction is given from the outside, and the element value is corrected using the successive approximation method, which requires a lot of effort. It requires a considerable amount of time. For example, if the D/A converter 1 has n bits, the correction amount is determined using n cycles, that is, 0 procedures. Therefore, as mentioned above, it is almost impossible to perform element value error correction during normal operations in electronic equipment.

The present invention is used in electronic equipment, such as A/D or D/A converters, in which multiple elements such as capacitors or resistors are required to have high relative accuracy, and the difference between the values of these elements is To provide an element value error correction circuit that can correct errors at high speed and obtain necessary relative accuracy.

Means for Solving Problem C] In the element value error correction circuit according to the present invention, a plurality of elements (for example, main capacitors C1 and C2) whose relative element value errors are to be corrected, and the elements An auxiliary element (for example, an auxiliary capacitor C3) is added to the
1 and C52), a comparator (for example, comparator 2) that detects the voltage generated due to element value errors in the plurality of elements, and an up/down amplifier that performs a count amplifier or countdown based on the input from the comparator. a down counter (e.g. up-down counter 4) and a multiplying digital-to-analog converter (e.g. D/A converter) which adjusts the equivalent value of said auxiliary element based on the input from said up-down counter; 1).

[Effect]

By taking the above measures, A/D 1li1'
In electronic devices such as D/A converters or D/A converters, where elements such as multiple capacitors or resistors are required to have high relative accuracy, it is possible to increase or decrease errors between the values of these elements. - High-speed correction is possible using the so-called follow-up comparison method that uses a counter, and as a result, element value error correction called cycle stealing, in which correction operations are performed in between the main operations of electronic equipment, is possible. It becomes possible.

〔Example〕

FIG. 1 shows an explanatory diagram of the main part circuit of one embodiment of the present invention, and the fourth
Symbols used in the drawings indicate the same parts or have the same meaning.

In the figure, 4 represents an up/down counter, CLK represents a clock signal, and U/D represents an up/down signal.

FIG. 2 shows a timing chart for explaining the operation of the embodiment shown in FIG. 1, and symbols used in FIG. 1 indicate the same parts or have the same meaning. do. Note that although error correction of capacitance values will be explained here, the present invention is of course not limited to this, and can be similarly implemented for, for example, resistors. Note that the D/A converter 1 in the present invention needs to be of a multiplication type.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to FIG. 2.

First, switch SZ is closed and the potential at connection point N1 is set to 0 [
■], and switch SW, 1 has contact R, and
The switch SW2 is operated so that the contacts G are respectively closed. As a result, the reference voltage VR is applied to the main capacitor C1 and the auxiliary capacitor C81, charges are accumulated, and the main capacitor C2 is grounded.

Next, the switch SZ is opened, and the switch SW1 is operated so that the contact G is closed, and the switch SW2 is operated so that the contact R is closed.

In this way, at the connection point Nl, C1+CSl≠C
A potential difference due to 200 S 2 appears.

The potential difference is compared with a reference potential by a comparator 2, and the result is input to an up/down counter 4.

Therefore, the up/down counter 4 performs counting up or down.

A clock signal CLK is input to the up/down counter 4, and the D/A converter 1 is controlled by its output.

Now, assuming that C2+C32>C2+C32, ten voltages are generated at the connection point N1, and accordingly, the comparator 2 gives a count-down command to the up/down counter 4.

Therefore, the output code of the up/down counter 4 becomes smaller as a value, and the output code is added to the D/A variable tA.
The partial pressure ratio of f31 also becomes smaller.

The D/A converter 1 applies control to the auxiliary capacitor C52 so that the apparent capacitance value becomes smaller. That is, in the auxiliary capacitor C32, the potential at the terminal opposite to the connection point N1 is raised.

When such an operation is performed, the potential at the connection point N1 drops to approximately 0 (V). Preferably, the potential at the connection point N1 is approximately 0 (V), so that the up/down counter 4 moves back and forth between the amplifier and down in small steps.

As mentioned above, when an electronic device is powered on, element values fluctuate due to temperature changes, and these fluctuations are relatively slow and last for a long time. A follow-up comparison type as in the invention is extremely advantageous.

In the above embodiment, the auxiliary capacitor C32 is 1
The apparent capacitance value above is changed, but it is also possible to install a large number of auxiliary capacitors with different capacitance values and select them as necessary. good.

〔Effect of the invention〕

In the element value error correction circuit according to the present invention, a comparator detects a voltage generated due to an element value error existing between a plurality of elements, and the detection result is input to an up/down counter. A count amplifier or a countdown is performed to generate an element correction value, and the element correction value is input to a multiplication type digital-to-analog converter to select an element value.

By employing the above configuration, electronic equipment such as A/D or D/A converters in which multiple elements such as capacitors or resistors are required to have high relative accuracy, can be used. Errors between element values can be corrected at high speed using the so-called follow-up comparison method that uses an up/down counter.As a result, the so-called correction operation is performed in between the main operations of electronic equipment. , element value error correction called cycle stealing becomes possible.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the main circuit of an embodiment of the present invention, Fig. 2 is a timing chart for explaining the operation of the embodiment shown in Fig. 1, and Fig. 3 is the principle of the element value error correction circuit. FIG. 4 shows an explanatory diagram of the main part of the circuit of the conventional example. In the figure, CI and C2 are main capacitors whose capacitance values should be matched, C3I and C32 are auxiliary capacitors used to match their capacitance values, sz, swl, and SW2 are switches, R and G are switch contacts, and 1 is D /A converter, 2 is a comparator, 3 is SAR, 4 is an up/down counter, N1 is a connection point, and VR is a reference voltage. Patent Applicant: Fujitsu Ltd. Representative Patent Attorney Akira Aitani Representative Patent Attorney Hiroshi Bebe - Procedures at IE (July 20, 1986 Kunio Ogawa, Commissioner of the Japan Patent Office)
1 (To the Patent Office Examiner) l Indication of the case Patent Application No. 192073 of 1985 2 Title of the invention Element value error correction circuit 3 Relationship with the person making the correction Case Patent applicant address Nakahara-ku, Yozaki City, Kanagawa Prefecture 1015 Kamiodanaka Name (522) Fujitsu Co., Ltd. Representative Takuma Yamaki 4 Agent Address 20-7 Toranomon-chome, Minato-ku, Tokyo (1)
The statement of the claims shall be amended as shown in the attached sheet. (2) The description in lines 18 to 20 of the specification is changed to a digital-to-analog converter (which adjusts the equivalent value of the element value by changing the voltage applied to the auxiliary element based on the output from the converter). For example, a configuration comprising a D/A converter 1).
, and correct it. (3) Replace Figures 1 and 4 with Figures 1 and 4 of the attached sheet. ``a plurality of elements whose relative element value errors are to be corrected, an auxiliary element added to the elements to correct the element value errors, and an element value error caused by the element value errors in the plurality of elements a comparator that detects the voltage to be applied to the auxiliary element, an up/down counter that counts up or down based on the input from the comparator, and a voltage that is applied to the auxiliary element based on the progress from the up/down counter.・An element value error correction circuit characterized in that a digital-to-analog converter for adjusting an equivalent value of a prime value is set to 0iff.

Claims (1)

[Claims] A plurality of elements whose relative element value errors are to be corrected, an auxiliary element added to the elements to correct the element value errors, and an element value error in the plurality of elements. a comparator that detects the voltage generated due to the voltage; an up/down counter that counts up or down based on the input from the comparator; and an up/down counter that counts up or down based on the input from the up/down counter; 1. An element value error correction circuit comprising: a multiplier type digital-to-analog converter for adjusting an equivalent value.