SU781835A1 - Sine-cosine digital-analogue converter - Google Patents

Description

(54) SINUS-COSINUS DIGITAL ANALOG CONVERTER

one

This invention relates to analog digital computing.

A sine-cosine digital-to-analog converter is known, containing a generator, a trigger, a switch, a 5-element. And, the counter and phase detectors have a rather high static accuracy of conversion, however, it has a low response rate due to the need to average output voltages with a fixed amplitude determined by the amplitude of oscillations of the generator Ts.

The sine-cosine digital-analogue converter is known iaif: a converter containing t5 serially connected linear digital-analog converter, switch adders, an octant and sign selector unit and performing a piecewise linear approximation of 20 sinusoids and cosine 2,

However, with a small number of approximation sites, this converter has a low conversion accuracy, and an increase in the number of sections 25 leads to its considerable complication (development).

The closest technical solution to the proposed is sine-cosine digital-analogue 3 (1

A converter containing a digital controlled resistor whose digital input is a digital input of the converter, two operational amplifiers with feedback resistors, and large-scale resistors, the input of the first operational amplifier, is connected to the first outputs of the keys of the digital controlled resistor, the second outputs the keys of the latter through the second large-scale resistor are connected to the input of the second operational amplifier, the combined terminals of the discharge resistors are digital controlled resistors The rails are the analog input of the converter, and their free terminals are connected to the inputs of the keys of the digital controlled resistor, the outputs of the operational amplifiers are the outputs of the converter.

This converter transmits the sine and cosine functions to rational fractions, which are ratios of first-order polynomials, and the maximum methodical approximation error is 3.33% 3J.

The drawback of the invention is low, the accuracy of the converter.

The purpose of the invention is to increase the accuracy of the converter.

The goal is achieved by the fact that a sine-cosine digital-analogue converter containing n-bit resistors, n two-position keys, whose control inputs are the bit inputs of the converter, the first and second operational amplifiers, the outputs of which are the outputs of the first scale resistor converter, connected between the input of the first operational amplifier and the first outputs of the two-position keys of the digital controlled resistor, the second outputs of which through the second scale resistor are connected to the input of the second operational amplifier; the information inputs of the on-off switches are connected to the first terminals of the discharge resistors of the digital controlled resistor, the first and second feedback resistors connected respectively to the input and output of the first and second operational amplifiers, additionally contain an adder, the first and the second inputs of which are connected to the outputs of the first and BTopofb Operational Amplifiers, respectively, the third input of the adder is, the analog input of the converter, the output of the totalizer Pa connected to the free conclusions of the discharge resistors.

The drawing shows the functional diagram of the sine-cosine digital-to-analog converter.

The converter contains an adder 1, n-bit resistors 2, 22 ..., 2f, n two-position switches and 3,, 3, ... / Np first and second operational amplifiers 4 and 5, first and second resistors b and 7 zi, the first and second scale resistors 8.9.

The Converter operates as follows.

The input voltage Up ,, is supplied to the third input of the adder 1, where it is controlled with the first and BtopisM output voltages of the device in accordance with the expression lg ,: "

h, jUBb, “+ K, Uex, where and, is the output voltage of adder 1; K K, K: - the scale factors of the first, second and third inputs of the adder 1; the first and second output voltages of the converter

The output voltage of the transformer is connected with the high voltage of the adder 1 by the following dependencies

YaYj / N .x.-t.iNlUi ..

)

lBbUi-i2l U ,, f, lN) .iqp

where Y, Yj are the conductance resistors 6 and 7 of the feedback Yg, Y are the conductances of the scale resistors 8 and 9; Y, - weight conductivity of the discharge resistor N - input code, in the range of change of the input code

About N | one,

device transfer ratios are equal

and

)

0SH.-)

vX))

and

Jeix2 3fiU)

UBX (H) + K, (mg These expressions are rational fractions, which are ratios of second-order polynomials. Calculation on a digital computer showed that they approximate the functions

Z, (N) A sin | - N,

Zg (ti) In cos | - N,

with a methodological error of not more than 0.16% in the range of changing the argument

ABOUT ; N: th 1, where A, B - scale factors.

The absolute magnitude and the sign of the scale of the coefficients / are determined by the magnitude and sign of the scale factor of the third input of the adder 1 and the conductivity of the resistors 6 and 7 of the backwash.

The technical and economic efficiency of the device consists in increasing the accuracy of the converter while maintaining the high-speed performance of the inertia-free digital-analogue converters. Converters.

Claims (3)

Invention Formula A sine-cosine digital-to-analog converter, containing a numbered l iBSHCtopoB, n two-position keys, the control inputs of which are the discharge inputs of the converter, the first and second operational amplifiers, the outputs of which are the outputs of the converter, the first scale resistor included included, included with the converter, included with the converter, included the output of the converter the ONE amplifier and the first outputs d into the jot of the position keys, the second bridges through the second scale. the resistor is connected to the input of the second operating terminal, information inputs The two switches are connected to the first output of the discharge resistors, the first and second feedback resistors connected, respectively, between the input and output of the first and second operational amplifiers, characterized in that, in order to improve the accuracy, it contains an adder, the first and second inputs of the core connected to the outputs of the first u of the second operational amplifiers. Accordingly, the third input of the adder is the analog input of the converter, the output of the adder connected to free discharge pins of HEJX resistors. Sources of information / taken into account in the examination1. USSR author's certificate N 452920, cl. H 03 K 13/02, 1974. 2. US patent number 4072940, class. 340-347, publ. 1978 3. Forward Germany No. 2741454, CL. G 06 G 7/26, published. 1978 (prototype).