SU1640824A1 - Digital-to-analog converter - Google Patents

Abstract

The invention relates to computing, in particular, to converters (Information forms, and can be used in digital-to-analog data conversion systems. The purpose of the invention is to expand the field of application by providing the possibility of generating a bipolar output signal while simplifying, Digital-Analog Converter contains 1 binary-weighted current driver, a block of 2 bit switches, three operational amplifiers 3-5, a source 6 of the reference voltage and six resistors 7-120 P A positive is provided by the appropriate organization of the links between the elements. 1 Il.

Description

The invention relates to computer technology, in particular to information form converters, and can be used in systems for converting digital information into analog. ''

The purpose of the invention is the expansion of the scope by providing the POSSIBILITY of forming a bipolar output signal while simplifying it.

The drawing shows a functional diagram of a digital-to-analog converter. fifteen

The digital-to-analog converter contains a driver of 1 binary-weighted currents, a block of 2 bit keys, the first 3, the second 4 and the third 5 operational amplifiers, a source of 6 20 reference voltage and six resistors 7-12 "

The digital-to-analog converter p> operates as follows.

The converted code Ν _βχ arrives 25 at the control inputs of the block 2 of the bit keys. At the exit of the first. an operational amplifier 3 (which together with the resistor 9 serves as the first current-voltage converter) is formed by a voltage proportional to the code Νβχ ._t _n = p _ and Bi = _ O ^and -Chtsi ^U ° ⁿ R62

Uon_Rl (Ί) where U _o ., _V is the output signal of the first ry X of the operational amplifier 3 and the digital-to-analog converter as a whole;

1 _0С p - total current flowing through the first times of the block '2 bit keys;

I is the total output current of the · shaper 1 binary weighted currents;

P _op - voltage source 6 of the reference voltage;

R ₆ and R - resistance of the resistor 9 and the resistor 11 sootvetst- ⁵⁰ venno;

η is the input code bit ”Voltage U ₃ at the output of the third operational amplifier 5 (suppose that the resistances of resistors 7-955 and 12 are equal to each other and equal to R, and the resistances of resistors 10 and 11 are equal to 2R) is equal to and = tm _ I Nbx, Uon

6WX Rj ~ 2 2. ’where R ^ and are the resistances of resistors 7 and 8, respectively”

For the inverting input of the second operational amplifier 4, the expression

I +

Up to * 2R

where 1dop ⁼ I “I Νθ _χ / 2 is the total current flowing through the second outputs of the block 2 bit keys”

Then we obtain the expression for current I in the form

I = U _on / R. (2)

From the expression (2) it follows that the total current I depends only on the value of the reference voltage U _on and the resistances of the resistors 7-12 and does not depend on the resistances of the discharge keys of unit 2 and the output resistance of the driver 1 of the binary-weighted currents, which ensures high accuracy of the conversion scale of the digital-to-analog converter »The latter is due to the presence of negative feedback, the circuit of which includes a second operational amplifier 4, driver 1 binary-weighted currents and block 2 bit keys.

Substituting the current value. I from (2) to (1), we obtain the expression for the output voltage of the digital-to-analog converter U _Bblx B in the form _тт _UonNftx U _O n ¹ out ~ 2 ^П ~ 2 ~ and for Ν _βχ = 0 π = - Ϊ · ²² ·· ^and & y 2 *. T »7, t _ U O P and for Ν _6χ - P _{B5 (} . _Ma ks ^ vy ^{- _} 2 ^_ '

those. in this digital-to-analog converter, a bipolar output signal is provided as a result of the appropriate organization of the connections between the elements.

Claims (1)

Claim A digital-to-analog converter containing a voltage reference source, a binary-weighted current generator, η of the outputs of which are connected to the corresponding information inputs of the bit key block, the control inputs of which are the input bus, the first current-to-voltage converter, made in the form of the first operational amplifier and the first a resistor connected between the output and the inverting input of the first operational amplifier, the output of which is the output bus, η of the first outputs of the block are keys are combined and connected to the inverting input of the first operational amplifier, the second current to voltage converter, made in the form of a second operational amplifier, the inverting input of which is connected to the η second outputs of the bit key block, the (n + 1) -th output of the binary-weighted current generator and the first output of the first current-limiting element made on the second resistor, the third operational amplifier, inverting the input of which through the second current-limiting element made on the third resistor is connected to the output of the first operational amplifier and through a third current-limiting element made on the fourth resistor, connected to the output of the third operational amplifier, the non-inverting inputs of the first, second, and third operational amplifiers are connected to the zero potential bus, the fourth and fifth current-limiting elements, made respectively on fifth and sixth resistors, the first output of the last of which is connected to the output of the reference voltage source, characterized in that, in order to expand the region and application by providing the formation of a bipolar output signal while simplifying, the output of the reference voltage source through the fifth resistor is connected to the inverting input of the second operational amplifier, the second output of the sixth resistor is connected to the inverting input of the first operational amplifier, the output of the third 25 operational amplifier is connected to the second output of the second resistor, the output of the second operational amplifier is connected to the input of the shaper of binary-weighted currents.