SU1168977A1 - Digital-to-analog logarithmic function generator - Google Patents

Abstract

A DIGITANOLOGICAL LOGARIFMIC TRANSMITTER containing an operational amplifier whose output is the output of a converter, and the first scale resistor, the source of reference voltage, is connected to the negative feedback circuit, the output of which through the second scale resistor is connected to the inverter with NO-03Aff Iff-JA-SHTT O. , to the input of the operational amplifier, connected by a non-inverting input to the zero potential bus, the first and second digitally controlled elements, the outputs of which are via the third and fourth, respectively the scale resistors are connected to the inverting input of the operational amplifier, the digital inputs of the first and second digital-controlled elements are connected to the information input of the converter, characterized in that, in order to improve the accuracy, an analog adder is connected to it, connected by summing input to the output of the reference voltage source and analog the input of the first digital (L controlled element, the output of the analog adder is connected to the analog input of the second digitally controlled element whose output is connected subtraction input of the analog adder, the first and second elements are tsifroupravl emye to-analog divider and voltage x 00 voltage. with SI S1

Description

The invention relates to hybrid computing and can be used in information measurement technology. The purpose of the invention is to improve accuracy. The drawing shows a functional diagram of a digital-to-analog logarithmic converter. The digital-to-analogue logarithmic converter contains the operational amplifier 1, four large-scale resistors 2-5, two digital-controlled elements 6 and 7, the source 8 of the reference voltage, an analog total.or 9. The digital-analogue logarithmic converter reproduces the dependence of the output voltage on the external binary positional code N) kUoen l4le-0-li-1 (1) LJ where K is a proportionality coefficient; Up is the direct voltage reference; - the maximum code value of the max digital value to be converted. The Converter operates as follows. Decoding is performed with a methodological error not exceeding 0.022%, as a result of reproducing the mathematical dependence of the form. ai | (ei) x) (xba, + a2 (.. (e-O where a, 2.1233x10-,, 4675x10, 4675x10 a 1.5387; Xe (0 Methodical error is defined as en + max (e- 11x3 L) f € tO, 0 Suppose x 0 -. (KUo from (2) we get a CE-Ov 1. U kUo a, + a (e- |) 9g b (a-) into the Current flowing into the summing point operational amplifier 1 from the input side, is equal to IJ I, + I, –I, I, Uo G,; and, 9 G, + G, VU, 9, the decrease (7) is obtained in the assumption of zero current consumption of the thawing input analog sum9 and its infinitely large impedance), G, is the conductivity of the scale resistor 3; Gj is equivalent to the input conductivity of the digital-to-analog divider type R-2R (G ,, 1 / R); j is the conductivity of scale resistor 4; G is the conductivity of scale resistor 5; the output voltage is transformed equally: Gy is the conductivity of the first scale resistor 2 in the feedback circuit of operational amplifier 1 Equalizing the coefficients with the corresponding powers of the independent variable in expressions (3) and (8), and the system of equations for determining the values of the parameters of the scale: resistors. (e-0 Ci5, 2V Cr G4 rro (MS (42 + 04 - (- Og + I4 solution of this system has the form, 1233-10-, G3 / G5 0,2563;

311689774

64/65 1.5387; Gj / Gf 15.566. That, ty (), approximating with the pointer, is provided by the reproducible error of the logarithmic mathematical-dependent function (1).

Claims (1)

A DIGITAL ANALOGUE LOGARITHMIC CONVERTER containing an operational amplifier, the output of which is the output of the converter, and the first scale resistor, a reference voltage source, the output of which is connected through a second scale resistor to the inverting input of the operational amplifier connected by a non-inverting input to the zero bus, in the negative feedback circuit potential, the first and second digital-controlled elements, the outputs of which, respectively, through the third and fourth scale resistors are connected are connected with the inverting input of the operational amplifier, the digital inputs of the first and second digital-controlled elements are connected to the information input of the converter, characterized in that, in order to increase accuracy, an analog adder is connected to it, connected by a summing input to the output of the reference voltage source 5 and the analog input of the first digital-controlled element, the output of the analog adder is connected to the analog input of the second digital-controlled element, the output of which is connected to the subtracting input of the analog sum ator, and the first and second digital-controlled elements are made on digital-to-analog voltage dividers. SU. „. I68977 (4) (6) 1 _g = I, + 1 ₂ + I, where