JPS60260231A - Digital analog converter - Google Patents

Abstract

PURPOSE:To eliminate the time difference of L, RCH outputs by providing a hold device holding voltages of L, RCH in response to the output of L, R channel CH of a D/A converter, and a signal hold device to either of the channels. CONSTITUTION:A signal inputted to a D/A converter 1 is separated into L and RCH signals, they pass respectively through amplifiers 4, 6 and held to voltage hold capacitors C10, 11 in response to the input signal respectively via switch SW8, 9 switched alternately by control signals 12, 13. The voltage of LCH subject to holding (10) is held to a signal holding C17 via a buffer amplifier 5 through an SW16 switched in synchronizing with an SW9 of the RCH. The voltage of RCH held in the C11 is outputted through a buffer amplifier 7 and an LPF3 and the signal of LCH held in the C17 passes through a buffer amplifier 15 and the LPF2, and outputted without time difference with the signal of RCH.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a digital-to-analog converter using a voltage hold device to synchronize the phases of an L channel and an R channel.

2. Description of the Related Art Structures and Problems Therein In recent years, with improvements in electronic circuit technology, digital signal processing technology has come to be used in stereo signal reproducing devices.

FIG. 1 shows a diagram of the principle of a digital-to-analog converter. 1
is a digital analog converter (hereinafter abbreviated as DA converter), 1a is a digital input terminal of the DA converter, 1
b is the output terminal of the DA converter, 2 is the b-pass filter (hereinafter abbreviated as LPF), 2a is the input terminal of the LPF, 2b
is the output terminal of LPF2. FIG. 2 is a waveform diagram at the output terminal 1b of the DA converter 1, and FIG. 3 is a waveform diagram at the output terminal 1b of the LPF 2.

The operation of the digital-to-analog converter configured as described above will be explained.

First, when a digital signal is input to the DA converter 1, an output corresponding to the value of this digital signal is output from the DA converter 1 to the terminal 1b. The waveform of the terminal 1b is as shown in FIG. 2, and contains high frequency components. So D.A.
The output of the converter 1 is input to the LPF 2, high frequency components are removed, and the output is outputted to the output terminal 2b of the LPF 2 as a waveform without high frequency components as shown in FIG.

Next, a conventional analog-to-digital converter will be explained. . FIG. 4 shows the configuration of a conventional analog-to-digital converter. 1 is a DA converter, 1a is a digital input terminal of DA converter 1, 1b is an output terminal of DA converter 1, 2 is an LPF for the L channel, 2a is an input terminal of LPF 2, 2b is an output terminal of LPF 2, and the above is the first Same as the figure. 3 is LPF for R channel, 3a is LPF3
3b is the output terminal of LPF3, 4, 5, 6°7 is a buffer amplifier, 8, 9 is a switch, 1o.

Reference numeral 11 represents a voltage holding capacitor, and reference numerals 12 and 13 represent switch control signals for the L channel and R channel.

The operation of the digital-to-analog converter configured as above will be explained.

Figure 5 shows the relationship between the waveforms of each part and the switching timing of the signals of each channel of LR.The input signal of the ODA converter 1 is that the L channel and R channel signals are input alternately at certain intervals (TO). This is the signal to be used. As a result, a waveform as shown in FIG. 6A corresponding to the value of the signal input to the DA converter 1 is output. When this output is an L channel signal, the switch 8 is turned on at the timing shown in FIG. 5C, and the L channel signal (voltage) is held in the capacitor 10.

This signal is input to the LPF 2 through the buffer 7 amplifier 6, high frequency components are removed, and an L channel signal is output. Similarly, the R channel signal is held in capacitor 11 by switch 9 and output through LPFs.

In the manner described above, the LRR channel signal can be reproduced as a stereo signal.

However, in the conventional configuration described above, FIG. 6E.

As shown in F, there is a drawback that a time difference (phase difference) occurs between the outputs of the L channel and the R channel.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a digital-to-analog conversion device that solves the above-mentioned conventional problems and can eliminate the time difference between the L channel and the R channel.

Structure of the Invention The present invention includes a pair of hold devices that hold L and R channel signals according to the L and R channel outputs of a DA converter, and either L or R for eliminating the time difference between the L and R channels. This is a digital-to-analog converter equipped with a voltage hold device installed on one channel, and can eliminate the time difference (phase difference) between the L channel and R channel, enabling highly accurate stereo playback. It is something that can be done.

DESCRIPTION OF EMBODIMENTS FIG. 6 shows a digital-to-analog converter according to an embodiment of the present invention.

In FIG. 6, 1 is a DA converter, 1a is an input terminal of the DA converter, 1b is an output terminal of the DA converter 1, 4, 5, 6, .
7 is a buffer amplifier, 8 and 9 are L and R channel switches, 12.13 are L and R channel switch control signals, 10.11 are L channel and R channel signal holding capacitors, 2 and 3
is LPF.

2a and 3a are the inputs of LPF2 and LPF3, respectively.
b and ab are the outputs of LPF2 and LPFa. The above is the same as the conventional example shown in FIG. 4. 16 is an L channel switch that operates in synchronization with the R channel switch;
7 is an L channel signal holding capacitor, and 16 is a buffer amplifier. - The operation of the digital-to-analog converter of this embodiment configured as described above will be explained below.

Conventionally, the signal 1a input to the DA converter 1 is separated into L and R channel signals, and output as L and R channel hold signals to the output terminals 5b and 7b of the buffer amplifier 6.7, respectively. Same as example. The signals at these output terminals 5b and 7b are the fifth
As shown in the waveforms in Figures E and F, a time delay t0 occurs. Here, when the output of the buffer amplifier 6 is synchronized with the R channel switch 9, the L channel switch 16 is operated, and the L channel signal is held again by the capacitor 17, the signal shown in FIG. 5G is obtained. It will be done. 6th
As is clear from FIGS. F and G, the time difference between the signals of buffers 16 and 7 disappears.

As described above, according to this embodiment, the time difference (phase difference) between the L and R channels is eliminated by placing a hold circuit synchronized with the R channel hold circuit after the L channel signal hold circuit. This enables highly accurate stereo playback.

Effects of the Invention The present invention has 11 DA comparators, an L channel and an R channel.
By providing a single voltage hold device for synchronizing the phases of the L channel and R channel for the pair of voltage hold devices for the channels, the time difference (phase difference) between the L channel and the R channel is eliminated. Accordingly, it is possible to realize a digital-to-analog conversion device that can obtain highly accurate stereo signal reproduction effects.

[Brief explanation of drawings]

Figure 1 is a principle diagram of the digital-to-analog conversion device, Figure 2 is an output waveform diagram of the DA converter in Figure 1, Figure 3 is an output waveform diagram of the LPF2 in Figure 1, and Figure 4 is a conventional digital-to-analog conversion diagram. FIG. 5 is a waveform diagram of each part of the digital-to-analog conversion device in FIGS. 4 and 6, and FIG. 6 is a circuit diagram of the digital-to-analog conversion device according to an embodiment of the present invention. 1...DA converter, 2,3...-LPF, 4°5, 6, . 7, 15...Buffer amplifier, 8, 9
...Switch, 10, 11.17--Voltage hold capacitor, 12.13... Control signal for L channel and R channel switch. Agent: Patent attorney Toshio Nakao and one other person

Claims (1)

[Claims] a digital-analog converter into which L-channel and R-channel signals are input at regular intervals; a pair of voltage hold devices for the L-channel and R-channel connected to the output side of the digital-analog converter;
A digital-to-analog converter comprising one voltage hold device for synchronizing the phases of the L channel and R channel signals output from the pair of voltage hold devices.