JPS6350122A - A/d and d/a converters - Google Patents

Abstract

PURPOSE:To prevent various malfunctions at the time of turning on a power source, by providing a switch for disconnecting a signal line, on input and output parts of an analog signal, and also, providing a controlling circuit for operating the switch only for a prescribed time at the time of turning on the power source. CONSTITUTION:On an inputting circuit of an analog signal in an A/D converter circuit 1, and an outputting circuit of an analog signal in a D/A converter part 2, simple switches 11, 21 for disconnecting a transmission line of the analog signal, and a muting circuit 3 for controlling an operation of said switches are provided, respectively. The switches 11, 21 for disconnecting the transmission line of the analog signal are provided on the inputting circuit of the analog signal in the A/D converter part, and the outputting circuit of the analog signal in the D/A converter part, respectively, and also, the switches 11, 21 are provided with the control circuit 3 which is operated only for a prescribed time at the time of turning on a power source, therefore, various malfunctions caused by shock noise which occurs at the time of turning on the power source can be prevented.

Description

[Detailed Description of the Invention] [Summary] An A/D converter and a D/A converter are integrated into one chip.
In the A/D and D/A converters that make up the i. This is intended to prevent various malfunctions at times.

[Industrial application field]

The present invention is an A/
The present invention relates to a circuit configuration of an A/D and D/A converter that includes a D converter and its inverse D/A converter on one chip.

It is desired that A/D and D/A converters do not malfunction themselves or cause trouble in external circuits due to noise generated when power is turned on.

[Conventional technology]

The circuit of the conventional 1-chip A/D and D/A converter is
As shown in the figure. In the A/D converter section 1 of the circuit, an analog input signal is suitably amplified by an amplifier 12, then encoded by a KOG 13, converted into a DIGIC raw signal, and output.

In the D/A converter section 2, a digital input signal is converted into an analog signal by a decoder 22, and then amplified by an amplifier 23 and output.

Both the A/D converter section 1 and the D/A converter section 2 are configured only with a signal format converter and an analog signal amplifier circuit, and are not provided with a circuit that takes into consideration the power-up time.

[Problem that the invention seeks to solve]

Therefore, in the A/D converter section 1, the shock noise when the power is turned on is input to the analog input, causing the recorder 13 to malfunction or cause a failure. The noise emitted from the device can cause external circuits to malfunction or cause failures.

[Means for solving problems]

As shown in Figure 1, these problems are caused by cutting off the analog signal transmission path in the analog signal input circuit of the A/D converter section 1 and in the analog signal output circuit of the D/A converter section 2. Simple switch 11.
21 and a control circuit 3 for controlling the operation of the switch.

(Function) In the A/D converter, the switches 11 and 21 that cut off the analog signal transmission path are connected to the analog signal input circuit.
/A converter is provided in each analog signal output circuit, and the switches 11 and 21 have a control circuit 3 that operates only for a certain period of time when the power is turned on. The problem can be solved by preventing malfunctions.

〔Example〕

FIG. 2 is a circuit diagram showing the configuration of a one-chip A/D, D/A converter according to an embodiment of the present invention.

11 and 21 in the figure are field effect transistors (FETs).
), 3 is a time constant CR
This is a time constant control circuit that controls the DC voltage supplied to the gate of the FET of the electronic switch 11.21.

In the A/D converter section 1, when the power is turned on, the potential of the terminal A is kept low for a certain period of time by the time constant control circuit 3, and the PE
When the gate voltage of T-switcher 1 becomes LOW,
The analog signal input circuit is disconnected.

After a certain period of time, C of the time constant circuit is charged and the potential to the terminal becomes high, and the gate voltage of the FET switch 11 becomes the old G)
When in state I, the analog signal input circuit is connected and the analog signal is input manually.

In the D/A converter section 2, when the power is turned on, the FET switch 21 similarly cuts off the analog signal output circuit for a certain period of time by the time constant control circuit 3.

The disconnection time of the above analog signal input/output circuit is:
Time constant Cl of time constant control circuit 3? It can be freely set by changing the value of .

Therefore, in the embodiment of the present invention, the A/D converter section 1 can prevent the malfunction of the Korg 13 due to noise when the power is turned on, by using the time constant control circuit 3 and the FET switch 11, and The A converter section 2 can prevent malfunctions in external circuits due to noise generated by its own decoder 22 when the power is turned on, using the time constant control circuit 3 and the FET switch 21.

〔Effect of the invention〕

As described above, the present invention has the effect of preventing malfunctions of the A/D and D/A converters themselves and malfunctions of external circuits due to shock noise when power is turned on.

[Brief explanation of drawings]

FIG. 1 is a principle diagram showing the configuration of an A/DSD/A converter according to the present invention, FIG. 2 is a block diagram showing the configuration of an A/D and D/A converter according to an embodiment of the present invention, and FIG. 3 is a conventional diagram. FIG. 2 is a block diagram of an example A/D, D/A converter. 1 and 2, 1 is an A/D converter section, 11 is a switch, 2 is a D/A converter section, 21 is a switch, and 3 is a control circuit.

Claims (1)

[Claims] An A/D in which an A/D converter (1) that converts an analog signal to a digital code and a D/A converter (2) that converts a digital code to an analog signal are configured in one chip.
In the D/A converter, the A/D converter (1
) and an analog signal output section of the D/A converter (2) are provided with switches (11, 21) for cutting off signal paths, respectively.
, 21) only when the power is turned on.