JPH09179688A - Analog signal processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute highly accurate digital conversion, to accurately digitize an analog signal with a low signal level and to secure a digital conversion range for an analog signal with a high signal level. SOLUTION: The analog signal processor is constituted of a signal selection part 2, an amplification part 3, an A/D conversion part 4, and a control part 5. Only one of plural input analog signals 1 is selected by the selection part 2 based upon an instruction from the control part 5 and inputted to the amplification part 3. The amplification part 3 capable of selecting previously set plural amplification degrees multiplies the amplification degree by N (the absolute value of the N is a real number >=1) to amplify the input signal by N based upon an instruction from the control part 5 and inputs the amplified input signal to the A/D conversion part 4. An A/D converted digital signal is multiplied by 1/N in the control part 5 and outputted to a using device 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog signal processing device for converting an analog signal into a digital signal,
In particular, a control device, an information processing device, a peripheral device thereof, a system using these devices, or an analog signal processing device suitable for use in applying a digital signal obtained by digitizing an analog signal to a measuring device for processing. Regarding

[0002]

2. Description of the Related Art In an analog signal processing device according to the prior art, an input analog signal is, if necessary, passed through a buffer circuit (buffer circuit), AD converted, and the value is used as a digital signal. To do.

[0003]

In the prior art, when an analog signal having a high signal level is converted into a digital signal with high accuracy, an error becomes large with respect to an analog signal having a low signal level. If you try to convert a low analog signal into a digital signal with high precision, the range of AD conversion of an analog signal with a high signal level will be narrowed, and if the signal input level rises even a little, clipping will occur, and it will be possible to accurately convert it to a digital signal It has a problem that it can not be done. The above-mentioned point becomes a serious problem when an analog signal processing device is used as a part of a measuring device and a plurality of analog signals having different signal levels are measured.

Further, in the above-mentioned prior art, it is difficult to reduce a total conversion error due to an error caused by an analog system and an error caused by an AD converter, and it is difficult to perform a highly accurate digital conversion. It has a problem that

An object of the present invention is to solve the above-mentioned problems of the prior art and to perform digital conversion with higher accuracy than the prior art by using the same AD converter as in the prior art. An object of the present invention is to provide an analog signal processing device which enables the analog signal having a low signal level to be converted into a digital signal with high accuracy and can also secure the range of digital conversion of the analog signal having a high signal level.

[0006]

According to the present invention, the above object is to convert a single or a plurality of analog signals into digital signals and output the converted digital signals to a device that uses the signals. The analog signal processing device includes an amplification unit and an AD conversion unit, and temporarily amplifies the input target analog signal N times (N is a real number whose absolute value is 1 or more) and then AD-converts the amplified signal. And then A
This is achieved by outputting a value obtained by reducing the D-converted digital signal to 1 / N.

[0007] Further, the above-mentioned object is to configure the amplification unit so that the amplification degree can be changed, measure the value of the input analog signal once, and confirm that the value of the amplified analog signal is within the allowable range of the AD conversion unit. This is achieved by setting the value of the amplification degree N of the amplification section so that

Further, the above-mentioned object is to perform a process of converting an analog signal into a digital signal a plurality of times for the same analog signal, and after averaging them, a value obtained by making the signal 1 / N or an analog signal This is achieved by converting the signal into a digital signal, making the signal 1 / N a plurality of times with respect to the same analog signal, and outputting the averaged value.

Generally, the main errors that occur when an analog signal is converted into a digital signal by an AD converter are the errors caused by the analog system that occur before the analog signal is input to the AD converter, and the AD converter. There are two types of error due to. The error caused by the analog system is
Although it increases almost in proportion to the size of the input signal, the error caused by the AD converter is independent of the size of the input signal.
Most of them are almost constant. These errors include, for example, relative accuracy, differential nonlinear error, offset error, and the like.

Therefore, as in the prior art, the error in the case where the inputted target analog signal is AD-converted via the buffer circuit is (a) the analog generated before the analog signal is inputted to the AD converter. The error due to the system and (b) the error due to the AD converter can be expressed as I + B.

On the other hand, according to the above-mentioned structure of the present invention, the analog signal is once amplified N times, then the signal is AD-converted, and the AD-converted signal is made 1 / N to be used. Therefore, the error in this case is a value obtained by dividing the sum of the errors c and d described below by N, that is, (c + d)
It can be expressed as ÷ N.

(C) The error caused by the analog system that occurs until the analog signal is input to the AD converter is proportional to the magnitude of the signal. That is, the error becomes a × N.

(D) Since the error caused by the AD converter is almost constant regardless of the magnitude of the input signal as described above, it has the same value as in the case of (b).

As a result, the error as a whole in the case of the present invention can be expressed as (c + d) / N since the value obtained by making the AD-converted signal 1 / N is a digital signal. Then, as described above, since c is N times a and n is the same value as b, the overall error in the case of the present invention is (c + d) / N = (b × N + b) ) ÷ N
= A + (b / N).

That is, according to the present invention, the error amount caused by the analog system is the same as that in the prior art, but AD
The error caused by the converter can be reduced to N / N, that is, 1 / N, and the conversion accuracy can be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an analog signal processing device according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an analog signal processing apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of an amplifier section. 1 and 2, 2
Is a signal selection unit, 3 is an amplification unit, 4 is an AD conversion unit, 5 is a control unit, 6 is a utilization device, 7 is an operational amplifier, 8 is a buffer (buffer amplification unit), 9 is an amplification degree variable amplification unit, 10, Reference numeral 11 is an amplification setting resistor, and 12 is a relay contact.

As shown in FIG. 1, an analog signal processing apparatus according to an embodiment of the present invention includes a signal selecting section 2 for selecting one of a large number of input analog signals 1 and a selected signal having a predetermined amplification factor. The amplification unit 3 that amplifies the analog signal, the AD conversion unit 4 that converts the amplified analog signal into a digital signal, and the entire analog signal processing device are controlled, and the AD conversion unit 4 performs predetermined processing on the AD-converted signal. In addition, the control unit 5 outputs the processed signal to the utilization device 6 that uses the processed signal.

As shown in FIG. 2, the amplifier 3 is connected to a buffer 8 formed by two operational amplifiers 7, a resistor 11, and a resistor 10 of which one is selected by a relay contact 12.
It is composed of a variable amplification amplifier 9 by an operational amplifier 7 whose amplification degree is determined by resistors 10 and 11.

In the analog signal processing apparatus according to the embodiment of the present invention configured as described above, the analog signal 1 to be digitized is selected by the analog signal selection unit 2 by the instruction of the control unit 5. , Amplifier 3
Is input to The amplification unit 3 can select a plurality of preset amplification degrees, and the amplification degree is set to N times (N is a real number whose absolute value is 1 or more) according to an instruction from the control unit 5. Therefore, the analog signal 1 is input to the AD conversion unit 4 after its level is amplified N times.

The signal input to the AD conversion unit 4 is AD-converted according to an instruction from the control unit 5, and the AD-converted digital signal is input to the control unit 5. The control unit 5 makes the input digital signal 1 / N and gives the calculated result to the utilization device 6.

As described above, the amplifying unit 3 is configured to include the variable amplification amplifier 9. Therefore, when the control unit 5 turns on one set of the relay contacts 12, one of the resistors 10 is turned on. Two resistors are selected and set to any amplification degree,
The input analog signal 1 can be amplified with the amplification degree. The amplification degree in that case is determined by the resistance value of the resistor selected from the resistors 10 divided by the resistance value of the resistor 11.

Although the above-described embodiment of the present invention has been described as amplifying the input analog signal N times, the amplification degree is such that the level of the amplified analog signal is within the allowable range of the AD conversion section 4. Need to be selected. Therefore, in the present invention, the input analog signal is once measured (measured by the control unit 5 with the value of the amplification degree N of the variable amplification degree amplifier being “1”), and then the level of the amplified analog signal is measured. However, it is possible to determine the value of the amplification degree N of the variable amplification degree amplifier so that it falls within the allowable range of the AD conversion unit 4.

When the input analog signal 1 is used as a measured value, the control unit 5 according to the present invention uses AD
The same analog signal is AD-converted from the conversion unit 4 to receive information digitized a plurality of times, the average value of these is obtained, and then the average value is divided by 1 and output. can do.

According to the above-described embodiment of the present invention, the input analog signal is once amplified N times, the amplified analog signal is AD-converted, and then the AD-converted information is converted into 1 / N. The same A
When the D converter is used, compared with the case of the prior art,
It is possible to obtain a highly accurate digitized signal.

When one embodiment of the present invention is used to measure a plurality of analog signals having different signal levels, m input analog signals are input (m is an integer).
Since the amplified signal is AD-converted and the AD-converted information is then divided by the amplification degree, the value can be used as a measurement value of the analog signal. Amplification can be set large for low analog signals and low for analog signals with a high signal level, and a wide measurement range can be secured and measurement accuracy can be easily improved. .

[0027]

As described above, according to the present invention, the same AD converter as in the case of the prior art can be used to perform digital conversion with higher accuracy than in the case of the prior art. It is possible to accurately convert an analog signal having a low signal level into a digital signal and to secure a range of digital conversion of an analog signal having a high signal level.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of an amplification unit.

[Explanation of symbols]

 2 signal selection unit 3 amplification unit 4 AD conversion unit 5 control unit 6 utilization device 7 operational amplifier 8 buffer (buffer amplification unit) 9 amplification degree variable amplification unit 10 and 11 amplification degree setting resistor 12 relay contact

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Oketani 1 Horiyamashita, Hinoyama, Hadano, Kanagawa Pref., General Computer Division, Hiritsu Manufacturing Co., Ltd. (72) Masato Nishikawa 1st, Horiyamashita, Hadano, Kanagawa Prefecture Hitachi Computer Data Engineering Co., Ltd.

Claims (1)

[Claims] 1. An amplifier and an AD converter in an analog signal processing device for converting a single or a plurality of analog signals into digital signals and outputting the converted digital signals to a device using the signals. And amplifying the input target analog signal N times (N is a real number whose absolute value is 1 or more), and then AD-converting the amplified signal,
After that, the analog signal processing device is characterized by outputting a value obtained by reducing the AD-converted digital signal to 1 / N.