JPH01212920A - Analog/digital converter and semiconductor integrated circuit device incorporating digital/analog converter - Google Patents

Abstract

PURPOSE:To eliminate an externally mount circuit and to improve measuring efficiency in the measurement of an overall characteristic of an A/D and D/A converter by connecting an output of the A/D converter and an input of a D/A converter directly in a semiconductor integrated circuit through the use of a changeover switch. CONSTITUTION:An output of the A/D converter 1 is led to a digital output terminal 2 or an internal bypass line 7 by a changeover switch 5. Moreover, a D/A converter 4 receives an input from a digital terminal input 3 or an internal bypass line by a changeover switch 6. The changeover switches 5, 6 are interlocked with each other and they are switched simultaneously to the position of the terminals 2, 3 or the internal bypass line 7. With the changeover switches 5, 6 switched to the position of the terminals 2, 3, the output of the A/D converter 1 and the input of the D/A converter 4 are connected to the output terminal 2 and the digital input terminal 3. With the changeover switches 5, 6 switched to the position of the internal bypass line 7, the output of the A/D converter 1 and the input of the D/A converter 4 are connected in the semiconductor integrated circuit device by the internal bypass line 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an analog/digital converter (hereinafter referred to as A/D converter).
This relates to a changeover switch used to measure the overall characteristics of an A/D converter and a D/A converter of a semiconductor integrated circuit device that has a built-in digital/analog converter (hereinafter referred to as a D/A converter). .

[Conventional technology]

Figure 2 shows a conventional semiconductor integrated circuit device with a built-in A/D converter and a D/A converter.
1) is an A/D converter, (2) is a digital output terminal,
(3) is a digital input terminal, and (4) is a D/A converter.

In the conventional semiconductor integrated circuit device described above, when measuring the overall characteristics of the A/D converter (1) and the D/A converter (4), connect the digital output terminal (2) and digital input terminal (3) outside the device. External devices such as switches are connected using circuits and measurements are taken.

[Problem to be solved by the invention]

In the conventional measurement method, an external circuit must be used, so there is a problem in that it is necessary to create a circuit when making a measurement.

The present invention has been made to eliminate the drawbacks of the above-mentioned conventional devices. /D converter and the above D/
When measuring the overall characteristics of the A converter, the purpose is to eliminate the need for external circuits and increase measurement efficiency.

[Means to solve the problem]

The present invention provides a semiconductor integrated circuit that includes an A/D converter and a D/A converter, and uses an output of the A/D converter and an input switch of the D/A converter to switch between an external terminal and an internal bypass line. In addition to doing so,
An internal bypass line connects the changeover switches, and is used to connect the output of the A/D converter and the input of the A/D converter.

[Effect]

The changeover switch in the present invention can be easily operated by external input and connects the A/D converter output terminal and the D/A converter input terminal in the semiconductor integrated circuit.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows an A/D converter and a D
1 is a configuration diagram of a semiconductor integrated circuit device incorporating a /A converter; FIG. In Fig. 1, (1) is an A/D converter, (
2) is a digital output terminal, (3) is a digital input terminal,
(4) is a D/A converter, (51, +61 are changeover switches, and (7) is an internal bypass line. FIG. 2 is an enlarged view of the broken line in FIG. 1.

The operation of the above embodiment will be explained with reference to FIGS. 1 and 2. The output of the A/D converter 111 is controlled by a selector switch (
5) leads to the digital output terminal (2) or the internal bypass line (sword). Also, the D/A converter (4) receives input from the digital terminal input (3) or the internal bypass line by the changeover switch (6). switch 1
5) and T6) are interlocked and terminals 121. Switches to +31 side and internal bypass line (7) side at the same time. If the selector switches (5) and (6) are switched to the terminals (21, (31) side, the output of the A/D converter (11) and the D/D
The input of the A converter (4) is connected to a digital output terminal (2) and a digital input terminal (3). When the changeover switches (51, (61) are switched to the internal bypass line (7) side, the output of the A/D converter (1) and the input of the D/A converter (4) are connected to the semiconductor integrated circuit via the internal bypass line (7). Connected within the circuit device.

Although two changeover switches are used in the above embodiment, it is also possible to use one of them, connect the three terminals of one of the changeover switch parts in advance, and make the changeover with one changeover switch.

〔Effect of the invention〕

As described above, according to the present invention, the changeover switch is used to connect the A/D converter output terminal and the D/D converter inside the semiconductor integrated circuit.
Since it can be connected to the A converter input terminal, the overall characteristics of the A/D converter and D/A converter can be easily measured, which has the effect of improving test efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a semiconductor integrated circuit device incorporating an A/D converter and a D/A converter according to an embodiment of the present invention, FIG. 2 is an enlarged view of the area within the broken line in FIG. A
1 is a configuration diagram of a semiconductor integrated circuit device incorporating a /D converter and a D/A converter; FIG. In the figure, (1) is the A/D converter, (2) is the digital output terminal, (3) is the digital input terminal, and (4) is the D/D converter.
A converter, 15), +61 is a changeover switch, (7
) is an internal bypass line. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A terminal that outputs a digital signal converted by an analog/digital converter (hereinafter referred to as an A/D converter) and a digital signal input to the digital/analog converter (hereinafter referred to as a D/A converter). The output of the A/D converter and D
A feature of the present invention is that the input of the /A converter can be directly connected within the semiconductor integrated circuit using a changeover switch. A semiconductor integrated circuit device with a built-in A/D converter and D/A converter.