JPS63269831A - Digital-analog conversion device - Google Patents

Abstract

PURPOSE:To sufficiently secure the dynamic range of an output even when a power source voltage is low, by using the same signal as a clock signal being used in a D/A converter as the signal to control a charge pump circuit. CONSTITUTION:When a control signal 12 is set at an H, a transistor Tr T-1 is turned on, and charges a capacitor 14, and when it is set an L, a Tr T-2 is turned on, and the driving terminal of the capacitor 14 goes to the same potential as that of a negative power source 6. At this time, the terminal on the diode side of the capacitor 14 goes to the potential lower than that of the negative power source 6 further, and becomes the output voltage of a negative power source 10 expanded through a diode 16. On the output voltage of the expanded negative power source 10 of the charge pump circuit 9, a ripple synchronized with the signal 12 of the circuit 9 is put. However, since the signal 12 and the clock signal 11 of the D/A converter are set equal, the ripple of the output voltage 10 of the negative power source 10 is synchronized with the clock signal 11. Therefore, the analog signal 8 of the D/A converter becomes the output with a low level of distortion without being affected by the ripple of the expanded negative power source 10 of the circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital/analog conversion device used in compact disc players, digital audio tape recorders, and the like.

[Prior Art] Fig. 3 is a block diagram showing a conventional digital/analog converter. In the figure, (1) is a digital signal, and (2) is an input digital signal (1) that is converted into an analog signal. (3) is an analog current output from the D/A converter (2), (4) is a current/voltage converter that outputs the input analog current (3) as an analog voltage, (5) ) is a current/voltage converter (4
) and a positive power supply for driving the low-pass filter (7), (6) is a negative power supply for driving the current/voltage converter (4) and the low-pass filter (7), and the low-pass filter (7) is a current /Cut unnecessary band signals output from the voltage converter (4). (8) is an analog signal output from the low-pass filter (7), and (11) is a clock signal of the D/A converter that operates the D/A converter (2).

Next, the operation will be explained. Digital signal (1) is D
The signal is input to the /A converter (2), is converted into an analog signal corresponding to the digital signal (1) within the D/A converter, and is output as a current output (3). This current output (3) is input to a current/voltage converter (4) driven by positive and negative power supplies (5) and (6), and is converted into an analog voltage. The unnecessary band within this analog voltage is cut by a low-pass filter (7), and the analog signal (8)
is output as

[Problems to be solved by the invention] Since the conventional digital/analog converter is configured as described above, the output voltage can only be obtained within a range limited by the power supply voltage, and the power supply voltage is low. There was a problem in that a sufficient dynamic range of output could not be ensured in some cases.

This invention was made to solve the above-mentioned problems, and aims to provide a digital/analog conversion device that can ensure a sufficient dynamic range of output even when the electric voltage is low. shall be.

[Means for Solving the Problems] A digital/analog conversion device according to the present invention includes a charge pump circuit that expands the power supply voltage and expands the dynamic range of the output in the power supply section, and controls the charge pump circuit. The same signal as the clock signal using the D/A converter is used as the signal.

[Operation] The digital/analog conversion device in this invention has D
By controlling the charge pump circuit in the power supply section using the same signal as the clock signal of the /A converter and expanding the power supply voltage and expanding the output dynamic range, the control signal of the charge pump circuit described above is displayed on the output. [b] It is possible to obtain an output with less distortion. 5 [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1, in which the same parts as in FIG. 3 are given the same reference numerals.

In Figure 1, (9) is a charge pump circuit that expands the power supply voltage, (10) is a negative power supply expanded by the charge pump circuit, and (12) is a control signal for the charge pump circuit, which is a control signal for the D/A converter. This signal is the same as the clock signal and repeats two states: "H" (high) and rLJ (low).

Next, the operation will be explained. In FIG. 1, the operation of obtaining an analog signal (8) from a digital signal input (1) is the same as in the conventional example shown in FIG. Negative power supply (6)
is expanded by a charge pump circuit (9) and supplied to a current/voltage converter (4) and a low-pass filter (7), thereby expanding the dynamic range of the analog signal output (8).

FIG. 2 shows a specific circuit configuration diagram of the charge pump circuit (12), in which (13) is the drive section of the charge pump circuit, (14) and (15) are capacitors that accumulate charge, and (16) is the drive section of the charge pump circuit. ), (17) are diodes as rectifying elements.

When the control signal (12) is rHJ, the drive section (1
The transistor (T-1) on the positive power supply side of 3) turns on, charging the capacitor (14). Next, when the control signal (10) becomes "L", the transistor (T-2) on the negative power supply side of the drive section (13) turns on, and the terminal on the drive section side of the capacitor (14) has the same potential as the negative power supply. becomes.

At this time, the electric charge charged in the capacitor (14) does not escape, so the diode side terminal of the capacitor (14) has a potential that is even lower than the negative power supply, and this is expanded through the diode (16). ) is the output voltage.

Enlarged negative power supply (10) of charge pump circuit (9)
There is a ripple synchronized with the control signal (12) of the charge pump circuit (9) on the output voltage of the circuit, but since this control signal (12) and the clock signal (11) of the D/A converter are the same signal, , the ripple of the output voltage (10) of the enlarged negative power supply (10) and the D/A
The clock signal (11) of the converter is synchronized so that the analog signal (8) of the digital-to-analog converter is synchronized.
) is the enlarged negative power supply (
10) It is not affected by the ripple of the output voltage and provides an output with less distortion.

In the above embodiment, a circuit with two positive and negative power supplies is shown, but a charge pump circuit may be provided in the power supply section of either the positive or negative power supply circuit. Further, in the above embodiment, a charge pump circuit is provided for the negative power supply, but a charge pump circuit may be provided for the positive power supply.If a charge pump circuit is provided for both the positive power supply and the negative power supply, the power supply voltage can be further expanded. , the same effect as the above embodiment is achieved.

[Effects of the Invention] As described above, according to the present invention, a charge pump circuit for expanding the power supply voltage and output dynamic range is provided in the power supply section, and a control signal for the charge pump circuit is used for a D/A converter. Since it is configured to use a single clock signal, a sufficient dynamic range can be obtained even when the power supply voltage is low, and an output with little distortion can be obtained as the output of the digital/analog converter.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a digital/analog converter according to an embodiment of the present invention, FIG. 2 is a specific circuit configuration diagram of a charge pump circuit that is a component of the digital/analog converter, and FIG. is conventional digital/
FIG. 2 is a block diagram showing an analog conversion device. In the figure, (1) is a digital signal, (2) l is D/
A converter, (3) is current output, (4) is current/voltage converter, (5) and (6) are power supply parts (positive power supply, negative power supply),
(7) is a low-pass filter, (8) is an analog signal, (
9) is a charge pump circuit, (11) is a clock signal for the D/A converter, and (12) is a control signal for the charge pump circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 3 Seiden

Claims (1)

[Claims] a D/A converter that is driven by a clock signal and converts an input digital signal into an analog current and outputs the analog current;
A current that outputs the analog current as an analog voltage/
A digital/analog conversion device comprising a voltage converter, a low-pass filter that outputs an analog signal by cutting unnecessary band signals in the output of the current/voltage converter, and a power supply section for the current/voltage converter and the low-pass filter. 2. A digital/analog converter according to claim 1, wherein the power supply section includes a charge pump circuit driven by the same signal as the clock signal to expand the power supply voltage and expand the dynamic range of the output.