UA11961U - Analog-to-digital converter for biological signals - Google Patents

Abstract

The proposed analog-to-digital converter for biological signals contains a pulse counter, a voltage-to-frequency converter, a time interval generator,and a voltage source. The voltage-to-frequency converter contains a switch, a pulse former, and a start circuit and several timing circuits that are connected in parallel. The start circuit contains a resistor and a light-emitting diode, which are connected in series. Each timing circuit contains an optoelectronic coupler with an optical positive feedback. The optical output of the start circuit is coupled with the optical input of the first timing circuit. The optical output of each timing circuit, excluding the last circuit, is coupled with the optical input of the next timing circuit. The optical output of the last timing circuit is coupled with the optical input of the pulse former. The output of the pulse former is connected to the control input of the switch. The first common point of the connection of the start circuit and the timing circuits is connected to the common point of the circuit of the proposed converter, and the second common point is connected to the output of the voltage-to-frequency converter. The input of the time interval generator is connected to the output of the voltage source.

Description

Description of the invention

The utility model relates to measuring and biomedical engineering, namely to information conversion devices and can be used in various automatic control systems in universal digital measuring devices and biomedical systems.

A well-known optoelectronic analog-to-digital converter (Bakmutsky V.D. Universal measuring device! and system!. Kiev, "Tehnika", 1979, p. 128, fig. 301), containing a discrete scanister with recurrent optical connections, a voltage source, a differentiating link, a measuring mechanism, a control unit 70 and a sawtooth voltage generator.

The disadvantage of such a converter is complexity.

An analog-to-digital converter was chosen as the prototype |Balakai V. G. et al. Integrated circuits! ADC and DAC. "Znergy", 1978, p. 72, fig. 1.23), containing a pulse counter, a voltage-to-frequency conversion unit, a time interval generator, the outputs of which are connected to the counter's counter and control inputs, 19 | voltage source.

The disadvantage is low reliability, due to the presence of a number of precision elements, the metrological failure of which leads to the failure of the entire device.

The basis of a useful model is the task of creating an analog-to-digital converter for biosignals, in which, due to the introduction of new elements and connections, the simplicity of the design of the analog-to-digital converter for biosignals is achieved, which increases the reliability and accuracy of the device, and with the aim of expanding the functionality when using analog-to-digital transformations of biosignals, the information in the converter is set only at the optical level, which allows it to be used in a chip integrated with the sensor for the introduction of living tissues with the output of information in digital form through the fiber to the processing terminal. 29 The task is achieved by the fact that in the analog-to-digital converter for biosignals, which contains a pulse counter, a voltage-to-frequency conversion unit and a time interval generator, the outputs of which are connected to the counter and control inputs of the counter, as well as a voltage source, a conversion unit of voltage to frequency contains a key, a pulse shaper and parallel-connected trigger and timer cells, and the trigger cell contains a resistor and a light emitter connected in series, each timer cell is made in the form of an optocoupler with positive optical feedback, the optical output of the trigger Ge) of the cell is connected to the optical input of the first time-setting cell, the optical output of each time-setting cell is connected to the optical input of each subsequent time-setting cell, the optical output of the last time-setting cell. cell is connected to the optical input of the pulse shaper, the output of which is connected to the control input of the key, "-- the first common point of the triggering and timing cells is connected to the common bus, and the second through the key is connected to the input bus of the voltage-to-frequency converter block , and the input bus of the time interval generator. (7 is connected to the output of the voltage source.

The drawing shows the structural electrical diagram of the device.

The device contains a pulse counter 1, a voltage-to-frequency conversion unit 2 containing a key 3, a pulse generator 4, parallel-connected triggering cell 5 and t timing cells 6.4...b4. Starting Z 50 cell 5 consists of a series-connected resistor 7 and a light emitter 8. Each timing cell c 64...bt is an optocoupler made of series-connected light emitters 94...U,4 and photodetectors

From" 104...10.4, connected by positive optical feedback from the optical output of light emitters 94...U,. to the optical input of photodetectors 104...10,4. The optical output of the light emitter 8 is connected to the optical input of the photoreceiver 10 of the first time-setting cell bi. The optical output of light emitters 94...9,4) of each time-setting cell 6.1...bu is connected to the optical input of photoreceptors 103...10,, of the next time-setting cell 61...bt. The optical output of the light emitter U, the last timing cell bl is connected to - the optical input of the pulse generator 4, the output of which is connected to the control input of the key 3. All timing cells 6...b/ are connected through the key C to the output bus 11 of the block 2 voltage to frequency conversion. The output of the generator of 12 time intervals is connected to the control input of pulse counter 1, which is made similarly

Gee! 20 block 2 voltage to frequency conversion, and the input bus of the time interval generator 12 is connected to the voltage source 13. and The device works as follows.

When the key C is closed, the converted voltage ) is supplied to the time-setting cells 64...b4, and the starting cell 5 of block 2 of the voltage-to-frequency conversion. At the same time, the emitter 8 29 of the trigger cell 5 begins to emit light. After that, the first time-setting cell 6.4 is triggered, since radiation from the trigger cell 5 enters its optical input c, then the second time-setting cell b" is triggered, etc.

The time after which the optical signal will appear at the input of the 4 pulse generator will be determined by the number of timing cells 64...bl and their activation time. When the last time-setting cell b 7 is triggered, the pulse generator 4 forms a short-time pulse, during which the key C is opened and the voltage of the SHO is disconnected from the 60 time-setting cells 61... bu, as a result of which they all extinguish during the time ta, , and this time must be less than the duration of the formed pulse

Ttas 2.

After the end of the pulse, the key C is closed again and the process is repeated from the beginning. 65 Thus, the pause between the pulses formed by the 4-pulse generator is approximately equal to the pulse tracking period, equal to

Tem ti, where M is the number of time-setting cells 6...bp in block 2 of voltage-to-frequency conversion; tu 7, the time of operation of the time-setting cell is 6h...bul. 5. In U. . and

Each timing cell 6-...bu, as a generative optocoupler from a photoreceiver and a light emitter with positive feedback optical communication, has a trigger time: 5-2 o, where | - optocoupler startup time on its optical input; ii" - the time of starting the optocoupler on its electrical input is equal to at tb le - 106

Iv) and where 4. is the input applied voltage.

We denote dt.107 by K, since this value is constant for this type of optocouplers. In addition, since 2", it can be assumed that

Kk, ride --

That is, the operation time of the optocoupler is inversely proportional to the applied voltage.

It follows that

Kk thx 8-06

Sh,

In this case, the pulse tracking period from the output of voltage-to-frequency conversion unit 2 and, accordingly, the pulse tracking frequency is equal to

K 1 IV)

Tu Mt. M---; Pe sht -- spe plyne yaITYA v

The frequency of following pulses at the output of the generator is equal to 12 time intervals

E 1 1 This is p che

And Mt MK

Where M is the number of time-setting cells of the 6...th generator of 12 time intervals.

The output code of counter 1 pulses is equal to the number of counter pulses received by the counter Ge"! the input of counter 1 for the time To from unit 2, the conversion of voltage into frequency is determined as follows:

Claims (1)

"- "- The formula of the invention is an analog-to-digital converter for biosignals, which contains a pulse counter, a voltage-to-frequency conversion unit and a time interval generator, the outputs of which are connected to the counting and control inputs of the counter, as well as a voltage source, which differs in that the conversion unit from voltage to frequency contains a key, a pulse generator and parallel-connected trigger and timer cells, and the trigger cell contains a series-connected resistor and a light emitter, each h . . K-4. and?" the timing cell is made in the form of an optocoupler with positive optical feedback, the optical output of the trigger cell is connected to the optical input of the first timing cell, the optical output of each timing cell is connected to the optical input of each subsequent timing cell, the optical output of the last timing cell is connected to optical input of the pulse shaper, the output of which is connected to the control input of the key, the first common point of the trigger and time-setting cells is connected to the common bus, and the second through the key is connected to the input bus of the voltage-to-frequency converter block, and Ge) the input bus of the time interval generator is connected to the output of the voltage source. (e)) -M bo b5