JPH02244823A - A/d converter - Google Patents

Abstract

PURPOSE:To obtain an A/D converter which can extend a measuring range without changing a D/A conversion circuit by performing the voltage comparison of an input signal with second and third comparators. CONSTITUTION:The input signal Sa is compared with the output voltage of a reference voltage generation circuit 4 by a second voltage comparator 2b, and also, the output voltage of the reference voltage generation circuit 4 is compared with a result amplified by an amplifier 8 by a third voltage comparator 2c. The above results are used in the judgement of two most significant bits as the A/D converter, and the output voltage of the reference voltage generation circuit 4 is supplied as an offset voltage to an adder circuit 10. Therefore, the output of the adder circuit in which the output voltage of the D/A conversion circuit 5 is added on the output voltage of the reference voltage generation circuit 4, or that of the adder circuit in which the former is added on the output voltage of the amplifier is supplied to a first voltage comparator 2a, then, A/D conversion is performed. In such a manner, the measuring range can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the field of measurement that handles analog signals as signals to be measured.

[Conventional technology]

Figure 2 shows a conventional successive approximation type A/D transformation system, and in Figure 1, S! 1ij signal to be measured, (1) is a buffer circuit that converts the impedance of the signal to be measured, (2) is a voltage comparison type comparator that compares the voltage of the signal to be measured and the D/A conversion circuit (4), (3) is a successive approximation register 4, 74) that accumulates the signal of voltage comparison type converter 4 (2).
15) is the reference voltage generation circuit, and 15) is the above-mentioned parrot voltage generation circuit (
A D/A converter circuit which inputs the voltage of 4) and generates an analog voltage corresponding to the data of the successive approximation register (3);
6) is a timing circuit that increases the timing of the movement of the Joki Souryu by 1, and Da is an A/D conversion value.

[Problem to be solved by the invention]

According to the above configuration, the measurement range of the A/D conversion device is determined by the resolution of the D/A conversion circuit itself, so in order to expand the measurement range, it is necessary to use a D with better resolution. There was a problem in that a /A conversion circuit was required, leading to an increase in price.

This invention was made to solve this problem, and aims to provide an A/D converter that can expand the measurement Q without changing the D/A converter circuit.

[Means to solve stomach problems]

The A/D conversion equipment provided in this invention electronically compares the input signal S5 with a second comparator and a third comparator, thereby determining the most significant two bits as an h/n conversion circuit. It is determined whether or not to supply the offset voltage to the adder circuit.

Therefore, 1 piece of paper can have a measurement range three times larger than the conventional measurement range.

[Effect]

The A/D conversion electric manufacturing device according to the present invention converts the input signal BS
is compared with the output voltage of the reference voltage generation circuit by the second voltage comparison comparator, and compared with the result of amplifying the output voltage of the P1 voltage generation circuit by the amplifier by the third voltage comparison comparator. The result is the judgment of the 4 upper 2 bits as an A/D converter, and the result is input to the timing circuit. As a result, if it is determined that the comparison results of the second voltage comparison comparator and the third voltage comparison comparator do not exceed the output voltage of the reference electron generation circuit, the first switch circuit is insulated and the reference The first switch circuit is suppressed so that the output 1itlE of the voltage generation circuit is completely supplied as an offset voltage to the adder circuit, and conventional A/D conversion is performed. Also,
Second Voltage Comparison Combare If it is determined that only the comparison result exceeds the stiffness voltage of the reference voltage generation circuit described in -F, the timing circuit selects the first switch circuit as the output voltage of the reference voltage generation circuit. Is the output voltage of the reference voltage generation circuit above? The offset voltage is applied to the 70-meter circuit. Therefore, the voltage comparison comparator No. 10 is supplied with the output of the adder circuit which is the D/A conversion circuit output voltage plus the output voltage of the base@electron generation circuit η0, thereby implementing the A/D conversion. Furthermore, when it is determined that the voltage has exceeded the third voltage comparison comparator, the above-mentioned timing circuit selects the -F-th switch circuit as the amplifier output voltage with double the gain, and outputs the D/A voltage to the first voltage comparison comparator. The output of the adder circuit obtained by adding the output voltage of the converter circuit plus the power voltage for the amplifier is supplied to perform A/Df conversion.

This makes it possible to have a measurement range three times that of conventional A/D conversion devices.

〔Example〕

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

In the figure, (l) to 16) are exactly the same as the conventional circuit indicated by -F.

In Figure 1 above, the wave meter side signal S input from the outside
11 is subjected to in-bitance conversion in the buffer circuit (1), and the output 1 voltage of the reference voltage generation circuit (4) is compared in the second voltage comparison type comparator (2b), and the result is sent to the register circuit (7). output to the timing circuit +61
Tsumata 30゛ Heart pressure comparison type comparator (2
In C), the instep force of the reference 1 pressure generation circuit 14) is set to gain 2.
The result of comparing the voltage amplified by doubling @ iM t81 is also the result of register circuit (7) and timing circuit f61.
The result of the input is the judgment result of the most significant two bits of this tit, and in the timing circuit (6) above, j is the second 1! The results of the comparison type comparator (2b) and the third electronic comparison type comparator (2C) are obtained and a control @ signal is output to the switch circuit 9). For example): Comparison result of the second voltage comparison type comparator (2b).

When it is determined that the output of the buffer circuit 111 is slightly smaller than the output voltage of the reference voltage generating circuit (4), the timing circuit 16+ controls the switch circuit (9) to be in the ground state, and Quasi-voltage generation circuit (4)
The output voltage of is not supplied to the adder circuit 1.

As a result, the output voltage of the adder circuit II is the same as that of the D/A
For this reason, the output voltage of the conversion circuit (5) is small, so a first voltage comparison type comparator (25) performs successive approximation type A/D conversion by comparing the voltage with the output voltage of the adding circuit (9). The result can be obtained in the successive approximation register (3).

The result of the successive approximation register (3) is sent to the second voltage comparison type comparator (2) which is forwarded to the register circuit (71).
b) and the results of the third (pressure comparison type combiner 4 (2c)) are accumulated and output as an A/D conversion data DB.

By the above operation, the conventional A/D variable 4fI result can be obtained.

In addition, when it is determined that the output of the second voltage comparison type comparator (2b) and the buffer circuit fl) is unusually larger than the output voltage of the reference voltage generation circuit (4),
In the above timing circuit (6), the above switch circuit (9)
is opened so that the output 1fFE of the pressure generating circuit (4) becomes conductive, and the output filling pressure of the reference voltage generating circuit (4) is supplied to the circuit iIG. ?:
As a result, the output voltage of the adder circuit 1 is the output voltage of the reference voltage generating circuit 14) and the D/A converter circuit 5).
The output voltage is 1701[]. Furthermore, the voltage ratio of the first voltage ratio II9 type comparator (2g)
Successive approximation type A/D conversion is performed by comparing the EfJIBilQ output voltage by one voltage, and the result can be obtained in the successive approximation register (3).

The result of the successive approximation register (3) is sent to the second direct voltage comparator (2) to the register circuit (7).
b) and the results of the third voltage comparison type comparator (2C) are crushed and outputted as A/D transformation data D.

By the above operation, a measurement range twice as large as that of the conventional A/D conversion result can be obtained.

9. Comparison result 1 of the third voltage comparison type comparator (1C) The output of the buffer circuit (1) is the output of the amplifier (1C).
8), the timing circuit 16) switches the switch circuit (9) to the output voltage f:
li! Control so that the output voltage of width switch; 8) becomes conductive 1. Output 11 of the above multiplier (8)! Pressure above? +
111 [supply to circuit Ill. Accordingly, the output filling pressure of the summing circuit aα becomes a voltage obtained by multiplying the output voltage of the 11111 amplifier (8) by η0 of the output voltage of the D/A converter 1-channel (5). Furthermore, the first voltage comparison type comparator (
2a) Dei N:1 Takashi.

Circuit 1111 output voltage and! Successive approximation type A/Df conversion is performed by comparing the voltages, and the result is stored in the successive approximation register (
3) can be obtained.

The result of the successive approximation register (3) is also the result of the second voltage comparison type comparator (2b) and the third voltage comparison type comparator (2C) which are sent to the register circuit (7). The A/D conversion data is stored and output.

Through the above operations, it is possible to obtain a measurement range three times larger than the conventional A/Df conversion result.

〔Effect of the invention〕

As described above, according to the present invention, the second voltage comparison type comparator and the third one-voltage comparison type comparator are used to
By comparing the voltage of the i-voltage generating circuit and the voltage twice that voltage, the first and second bits of one voltage are determined and set as an offset M″+: to the adder circuit.

Compared to the conventional A/'D conversion device/Dragon due to this operation, 3
Can have twice the measurement range

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an apparatus according to an embodiment of the present invention, and FIG. 21 is a configuration 1g showing a conventional apparatus. In v4, (+) is a buffer arrow path, (2!l) is the 10'' pressure comparison type comparator, (2b) is the 20' positive pressure comparison type Conhaleley*, (2c) hth H voltage comparison Type comparator, (3) is successive approximation register,
14) is the base ff1i! pressure generation circuit, (5) is a D/Af conversion circuit, i6) is a timing circuit, (7) is a register circuit, (8) is an amplifier, 19) is a switch circuit,! 11 is the mxra path. In addition, the same symbols in one figure refer to the same or corresponding parts.

Claims (1)

[Claims] A buffer circuit that converts the impedance of a measured signal given from the outside, and a D/A that converts the output voltage of the buffer circuit.
a first voltage comparison type comparator that compares the voltage with the conversion circuit output voltage; a successive approximation register into which the comparison result of the first voltage comparison type comparator is input and whose operating speed is controlled by a timing circuit; In an A/D conversion device that includes a D/A conversion circuit that converts the output of a successive approximation register into an analog voltage, and a reference voltage generation circuit that supplies a reference voltage to the D/A conversion circuit, a second voltage comparison type comparator that compares the voltage between the circuit output voltage and the buffer circuit output; and a third voltage that compares the output voltage of the reference voltage generation circuit with the buffer circuit output after amplifying the output voltage of the reference voltage generation circuit with an amplifier. a comparison type comparator, a first switch circuit for selecting the output voltage of the D/A conversion circuit and the output voltage of the amplifier by the timing circuit, an output selected by the first switch circuit and an output of the D/A conversion circuit; 1. An A/D conversion device comprising: an addition circuit that adds a voltage to a voltage.