JPS595741A - Digital to analog converter - Google Patents

Abstract

PURPOSE:To output the voltage across a capacitor as an analog voltage and to simplify circuit constitution, by applying the capacitor with a digital signal applied between one terminal of a resistance element and the ground through a diode. CONSTITUTION:When there is a pulse input which holds a terminal A at a high level, the capacitor C is charged through a diode D1 and the output at an output terminal Va increases. On the other hand, when there is a pulse input which holds a terminal B at a low level, the capacitor C is discharged through a diode D2. At this time, the output Va varies in accordance with control based upon the frequency of the charging and discharging of the capacitor C, i.e. the digital signal. Then, the constants of the R and C are set to proper values to obtain the output Va with small step width.

Description

Detailed Description of the Invention +11 Technical Field of the Invention The present invention relates to a digital-to-analog converter that can be realized with a simple configuration.

121 Prior Art and Problems The conventional digital-to-analog converter had a complicated configuration as shown in FIG. That is, a digital (serial input up-down counter as No. 1)
When counting from NT K and opening/closing the switches SWO to 5w3Y outputs "o" and "l" corresponding to the output terminals and Q, the value of voltage Vll-VL is divided by resistance and output as an analog signal to terminal C OUT. v1 is obtained. This analog output V, is discrete, and the trap of making the step m small requires a large-scale hardware.

(2) Purpose of the Invention An object of the present invention is to provide a digital-to-analog converter that is capable of analog JIK conversion with a relatively simple circuit configuration and a small step width.

141 Structure of the Invention The structure of the present invention to achieve the above-mentioned object is that a digital signal Y applied via a diode between m- and *j@ of a resistance element is connected between the other end of the resistance element and ground. By applying voltage to the capacitor, the voltage t across the capacitor is
The idea is to use an analog method.

(5! Embodiment 21 of the invention is a 4S diagram showing an embodiment of the invention, in which terminals A and B represent digital 4G human power terminals, and when there is no input, terminal A is "L". is held at "H" level and an input signal of "H" level is applied.
''' and human power at the level "°L" is applied.D
l, D2 are connected with diodes in the conduction direction shown, and R
is a resistive element, and the above-mentioned digital signal No. 46 is applied between one end on the diode side and ground. C is a capacitor connected between the leak of the resistive element and the ground, and the voltage across the capacitor becomes the analog output v1. When the pulse input to the terminal A4 is set to "H" level, the capacitor a'4 passes through the diode D1, and the output from the output terminal va becomes large. -Multiple terminal Bg“
The capacitor C is discharged through the switching diode D2Y of the pulse input which is set to L" level.The output V changes according to the number of repetitions of the switching capacitor C, that is, the control by digital No. 15, so it is easy to A converter is obtained. By appropriately selecting the constants of 'CR and C, outputs V and Y with small step widths can be obtained.

m3 figure f! A circuit example χ shown in FIG. 2 is applied to the distortion removal circuit for the run pulse signal. IN corresponds to an input terminal for a pulse signal train having distortion, DT corresponds to an output terminal of a distortion detection control circuit, and B corresponds to an input terminal B in FIG. Normally, terminal A4 is set to "L" level and terminal BY is set to "R" level.

When there is a pulse input to the terminal IN and there is distortion, the distortion detection control circuit DT outputs "H" to the terminal, and when there is no distortion, it outputs "L" to the terminal B. Therefore, when there is distortion in the signal input, the capacitor C is charged through the resistor R4, and the potential across the capacitor C becomes high.

The potential is fed back to the adder 2 and superimposed on the input signal in a direction that reduces distortion. When the distortion disappears, the potential of the capacitor C decreases, and the potential of the capacitor C is raised again when the next distortion occurs. By forming a number of resistive elements and capacitors that are sufficiently thick compared to the period of distortion detection, distortion can be removed from the input signal and a clean output signal NH3 can be obtained.

+61 Effects of the Invention In this way, according to the present invention, a digital-to-analog converter with a small step width can be obtained even with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a configuration example of a conventional digital/7-analog converter, Fig. 2 is a diagram showing the configuration of an embodiment of the present invention, and Fig. 3 is a specific application example of Fig. 2. FIG. R...Resistance element C...Capacitor D1. D2...Diode DT...--Distortion detection control circuit% Applicant: Fujitsu Co., Ltd. Representative Patent Attorney Eisuke Suzuki 2

Claims (1)

[Claims] A digital signal applied between one end of the resistive element and ground via a diode is applied to a capacitor connected between the other end of the resistive element and ground, thereby producing an analog output of the voltage across the capacitor. Digital to analog converter.