JPH04299616A - Isolation type high speed a/d converter - Google Patents

Abstract

PURPOSE:To obtain the insulation type A/D converter which prevents production of interference noise between analog and digital signals and implements substantially high speed conversion. CONSTITUTION:An input analog signal is converted into an optical energy by an LED array 10 and the energy is passed through a luminous quantity attenuation hole 11 having various hole areas. The light strikes on a photodiode array 12, in which an optical electromotive force is produced and converted into a digitized electric signal energy and the result is outputted to an encoder 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isolated A/D converter, and more particularly to an isolated high speed A/D converter using a light amount coupling function.

0002

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional flash A/D converter. In the figure, 1 is a comparator that compares the input voltage of an analog signal with a reference voltage and outputs ON/OFF digitally, 2 is an encoder that converts the output from comparator 1 into a code, and 3 is encoder 2, which performs the next conversion. 4 is a strobe input that holds the output of comparator 1 to keep the data stable while the output of encoder 2 moves to latch 3.

Next, the operation will be explained. Flash A
In the /D converter method, if you want to output an n-bit signal, 2n -1 comparators 1 are arranged in the input stage, and one input terminal of each comparator 1 has 1LSB.
Input the comparison voltage from the reference voltage, which is obtained by dividing the analog full-scale value in increments. When an analog signal is input, each comparator 1 operates at the same time, compares the input voltage of the analog signal with a reference voltage, and digitally outputs ON/OFF.

[0004] The output from comparator 1 is encoder 2
is converted into a binary code or other required code, and the conversion result is stored in the latch 3. Strobe input 4 keeps the conversion result of encoder 2, which is transferred to latch 3, stable by holding the output of comparator 1, and latch 3 keeps the converted result stable while the next conversion is being performed. It is stored as data.

[0005]

[Problem to be solved by the invention] Conventional flash A/
Since the D converter is constructed as described above, there is often no insulation between the analog signal input section and the encoder 2, and there is a problem in that interference noise occurs between the analog and digital signals. Also flash A
In order to achieve isolation of analog signals with the A/D converter, it is necessary to insulate the analog signals at a stage before the conventional flash A/D converter shown in Figure 5, which involves first applying a high-frequency carrier wave. However, since the transformer coupling section cannot handle modulated waves of very high frequency, it is impossible to isolate high-output analog signals.

The present invention was made to solve the above-mentioned problems, and provides an isolated high-speed A/D converter that eliminates the generation of noise between analog and digital signals and does not require an analog signal isolation process. The purpose is to obtain.

[0007]

[Means for Solving the Problems] An isolated high-speed A/D converter according to the present invention includes an analog signal input section, a light emitting diode array that converts the input analog signal into optical energy, and a light emitting diode array that converts the input analog signal into optical energy. a photodiode array that converts the light energy forming the 2-n sequence into digitized electrical signal energy; It consists of an encoder that performs conversion and a latch that stores the code conversion results.

Furthermore, the isolated high-speed A/D converter according to the present invention is provided with a ladder network and a flash type comparator at a stage before the light emitting diode, and is provided with an optical coupling hole instead of a light attenuation hole.

Furthermore, the insulated high-speed A/D converter according to the present invention is configured to directly pass external light (natural light) through a light attenuation hole instead of using light energy from a light emitting diode.

0010

[Operation] In the present invention, since an analog input signal is converted into optical energy and used, interference noise between analog and digital signals is prevented, and an analog signal isolation step is not required.

[0011]

[Embodiment] FIGS. 1(a) to 1(d) are a configuration diagram and a sectional view showing an isolated high-speed A/D converter according to an embodiment of the present invention. In the figures, the same reference numerals as in FIG. 4 indicate the same parts. , 10 is an LED array that emits light according to the input analog signal in nbit, and 11 is a digital 2
12 is a photodiode array that performs digital conversion by generating a photovoltaic force by applying the light that has passed through the light attenuation hole 11; 13 is an LED array 10 and a photodiode array 12; This is a diffuser plate installed in the

Next, the operation will be explained. Same figure (b)
When it is desired to output a 4-bit signal as in the example shown in FIG. Since the LED array 10 is a point light source, a diffuser plate 13 is added to each array as necessary in order to make the light emission uniform from a surface. Next, L.E.
A digital 2-
Form an n array. The light forming the 2-n series is applied to the photodiode array 12 to generate a photovoltaic force,
Convert into digitized electric signal energy. Since the photodiode array 12 is a point light-receiving element, a diffuser plate is added as necessary, like the LED array 10, in order to perform surface light reception. Through this process of light intensity coupling,
This constitutes an interface in which signals are isolated between the analog signal input section and the output of the photodiode array 12.

In this embodiment, as described above, the input analog signal is converted into optical energy by the LED array 10, passed through the light attenuation holes 11 having different hole areas, and applied to the photodiode array 12 to generate photovoltaic energy. Since the signal is generated and converted into digitized electrical signal energy before being output, the signal is isolated at the interface between the analog signal input section and the photodiode array 12 output, so noise generation between analog and digital is prevented. do not have. In addition, the conventional analog signal isolation process is not necessary, and since signal transmission between the analog signal input section and the 12 outputs of the photodiode array is performed by inputting and outputting optical energy, conversion between analog and digital is essentially faster. An isolated high-speed A/D converter can be obtained.

In the above embodiment, the analog signal input is directly caused to emit light by the LED array 10, but in another embodiment of the present invention shown in FIG. 10, the signal that has already been digitized by the comparator 1 is converted into optical energy by the LED array 10, and is passed through the optical coupling hole 14 installed in place of the light attenuation hole 11 to be connected to the photodiode array. Enter 12. This optical coupling hole 14 is arranged so that the elements constituting each of the LED array 10 and the photodiode array 12 correspond to each other on a one-to-one basis, and the light energy from one element of the LED array 10 is connected to an unpaired photodiode. Since this is only to prevent erroneous input to the elements of the array 12, all holes need only have a uniform area.

Furthermore, as shown in the third embodiment of the present invention shown in FIG. A similar effect can be achieved as a high-speed isolated A/D converter that directly converts the energy of external light into digital data.

[0016] The steps after the digitized signal is input to the encoder 2 are the same as in the conventional example, so a description thereof will be omitted.

[0017]

[Effects of the Invention] As described above, according to the present invention, since the interface between the analog signal input section and the photodiode array output is insulated by coupling the amount of light, there is essentially no noise generation between analog and digital. This has the effect of providing an isolated ultra-high-speed A/D converter that performs high-speed digital conversion.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram and a sectional view showing an isolated high-speed A/D converter according to an embodiment of the present invention.

FIG. 2: Isolated high-speed A/A according to a second embodiment of the present invention.
FIG. 2 is a configuration diagram and a sectional view showing a D converter.

FIG. 3: Isolated high-speed A/A according to a third embodiment of the present invention.
It is a block diagram which shows a D converter.

FIG. 4 is a configuration diagram showing a conventional flash type A/D converter.

FIG. 5 is a configuration diagram showing an analog signal isolation process at a pre-stage of a conventional flash type A/D converter.

[Explanation of symbols]

1 Comparator 2 Encoder 3 Latch 10 LED array 11. Hole for light attenuation 12 Photodiode 13 Diffusion plate 14 Optical coupling hole

Claims (3)

[Claims] 1. An A/D converter that inputs an analog signal and outputs a digital code corresponding to the analog signal, comprising: an analog signal input section; and a light emitting diode array that converts the input analog signal into optical energy. and a light attenuation hole that allows the light energy to pass through and forms a digital 2-n array;
A photodiode array that converts optical energy forming an n series into digitized electrical signal energy, an encoder that performs desired code conversion on the electrical signal energy, and a latch that stores the code conversion result. An isolated high-speed A/D converter characterized by: 2. The insulated high-speed A/D according to claim 1, further comprising a ladder network and a flash-type comparator at a stage before the light emitting diode, and a light coupling hole instead of a light attenuation hole. D converter. 3. The isolated high-speed A/D converter according to claim 1, wherein external light (natural light) is directly passed through the light amount attenuation hole instead of the light energy generated by the light emitting diode.