SU758202A1 - Exponential decoding converter - Google Patents

Description

The invention relates to hybrid computing and can be used in automatic control devices and other areas of technology where digital-to-analog conversion is required according to the law (/) where the independent variable X is presented in the form of binary codes, and the dependent variable Y in the form of voltage direct current V.

Known exponential converter containing a digital code decoder and a resistive matrix type K - 2K [ΐ]. The input terminals of the device are connected to the corresponding inputs of the decoder, the output Bus ·. ' which are connected to the control inputs of the keys of the resistive matrix K -2K. The output of the resistive matrix is the output of the device as a whole. However, this converter requires a large amount of equipment for its implementation, since the number of links of the K-2K resistive matrix increases depending on the number of bits of the converted code;

The closest technical solution is a functional decoding converter that performs decoding according to the law of the exponential function G2].

The prototype contains an operational amplifier with a resistor in the feedback circuit, a first scaled resistor, a first digital controlled resistor, a positive polarity reference voltage source, a second digital controlled resistor, a second scaled resistor and a negative polarity reference voltage source. ‘

Input operational DC amplifier with a resistor in the circuit; The feedback loop is connected through a series-connected series resistor and the first digital controlled resistor with the output of the source of uninterrupted sound ^:. . positive voltage pole It is also connected through the second digital controlled resistor, shunted by the second large-scale resistor, to the output of the negative polarity reference voltage source. The output of the operational amplifier is the output of the converter as a whole.

A disadvantage of the known converter “is its limited accuracy. ''

The aim of the invention is to improve the accuracy of the Converter.

To achieve this goal, in an exponential decoding converter containing digital controlled resistors and scale resistors, the first of which is connected to the feedback of the operational amplifier, the output of which is the output of the converter, a second scale resistor and a first digital controlled resistor are connected in series to the inverting input of the operational amplifier its non-inverting input through a third scale resistor is connected to. the output of the reference voltage source, the control inputs of the digital controlled resistors are connected to the input of the converter, the second digital controlled resistor is connected between the common output of the first digital controlled resistor and the second scale resistor, the second output of which is connected to the output of the reference voltage source, non-inverting input of the operating the amplifier is connected to the zero potential bus through the fourth large-scale resistor.

A diagram of an exponential decoding converter is shown in the drawing.

The converter contains an operational amplifier 1 with a large-scale resistor 2 in the feedback circuit, large-scale resistors 3 and 4, a reference voltage source 5, a large-scale resistor b, and digital controlled resistors 7 and 8.

The converter operates as follows. Decoding is carried out with a methodological error as a result of reproducing a dependence of the form:

θ4θΉ2 ~ ^ki o ^e

-e (g)

In steady state ^{1, the} output voltage of the converter is _ Г, θί, о к * в. Oe 4 θ * + 2 θ

O) where is relative; value * ^{ax of the} input code;

N is the current code value of the converted digital quantity;

K is the coefficient of proportionality;

N maximum value

DAS1KS code;

and · is the voltage value of the reference voltage of the reference source 5;

and - output voltage; '

-conductivity of resistors and 2, respectively;

C - the maximum value of the conductivity of digital, controlled resistors and 8;

N and resistance resisto ³ ditch -3 and 4, respectively.

If you accept .....

-4,

Ϊ1 k "then we get the expression corresponding to the expression (2) at K = 1/4

The use of the proposed exponential decoding converter, which provides, along with a digital-to-analog converter, a computational operation due to the structural characteristics of the device, allows one to obtain a higher-precision reproduction of the function, which is explained by the use of only a single reference voltage source

Claims (1)

Claim An exponential decoding converter containing digital controlled resistors and scale resistors, the first of which is included in the feedback of the operational amplifier, the output of which is the output of the converter, the second scale resistor and the first digital controlled resistor connected in series to the inverting input of the operational amplifier, and the non-inverting input operational amplifier through a large-scale resistor connected to the output of the voltage reference sources, the control inputs of the digital th controllable resistors are connected to the inverter input of the r l and h and w and d w i with the fact that, in order to improve accuracy, it second digitally controlled resistor connected between the common output of the first digital upra-. a resistor and a second scale resistor, the second output of which is connected to the output of the reference voltage source, the non-inverting input of the operational amplifier is connected to the zero potential bus through the fourth scale resistor.