JPH04176164A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To enable defective points to be easily detected and to integrate a semiconductor integrated circuit on the same chip by a method wherein it is selected through control signals inputted to a circuit for selecting one of two connections : one is that the input and the output signals of a digital circuit and an analog circuit are connected to input-output signals from the outside, and the other is that the input and the output signals of a digital circuit and an analog circuit are connected to each other. CONSTITUTION:A digital circuit 2 and an analog circuit 3 are provided inside the whole chip 1, and an input wiring 23 and an output wiring 24 of the digital circuit 2 are connected to the analog circuit 3 with an input wiring 33 and an output wiring 34 through the intermediary of a selection circuit 4 or to outer wiring 16 and 17 through the intermediary of an input wiring 41 and an output wiring 42. When a normal state connection control signal is inputted to the selection circuit 4 from a control signal input 15, the inner output signal 23 and the inner input signal 24 of the digital circuit 2 are connected to the analog circuit 3 through the intermediary of the selection circuit 4 passing through the wirings 33 and 34, whereby the chip 1 starts a normal operation as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor integrated circuit, and particularly to a semiconductor integrated circuit in which analog circuits and digital circuits are mixed.

[Conventional technology]

In a conventional analog/digital mixed semiconductor integrated circuit, a digital circuit 2 and an analog circuit 3 are integrated in the same chip 1, as shown in FIG. They are connected by wires 23 and 24. The outside of the chip 1 and the digital circuit 2 are connected by two sets of wiring 21 and 22.
The outside of the chip 1 and the analog circuit 3 are connected by two sets of wires 31 and 32. The entire chip 1 includes digital input/output wiring 11, 12 . and connected to the outside via analog input/output wiring 13 and 14.

During actual operation, digital signals are input through the wiring 11,
After being processed by the digital circuit 2, it is input to the analog circuit 3 through the wiring 23, or outputted to the outside through the wiring 12. A signal input to the analog circuit 3 through the wiring 23 is converted into an analog signal by the analog circuit 3 and then processed, and outputted to the outside as an analog signal from the wiring 13, or converted into a digital signal and then sent to the wiring 2.
4 to the digital circuit 2. On the other hand, the analog signal is inputted from the wiring 14, processed by the analog circuit 3, converted into a digital signal, and then inputted from the wiring 24 to the digital circuit 2, or outputted from the wiring worker 3 to the outside. A signal inputted to the digital circuit 2 from the wiring 24 is processed by the digital circuit 2, and then inputted to the analog circuit 3 from the wiring 23 or outputted from the wiring 12 to the outside.

[Problem to be solved by the invention]

In such conventional analog/digital mixed integrated circuits, digital circuit 2 and analog circuit 3 are directly connected inside chip 1, so if there is a problem with the overall operation, the defective part will be located in digital circuit 2. There was a problem in that it was not possible to distinguish whether it was in the analog circuit 3 or in the analog circuit 3. For this reason, as shown in Fig. 4, the digital circuit and the analog circuit are made into separate chips 5 and 6, and after confirming the normal operation of each, the method is to connect them with wires 53 and 54 to confirm the overall operation. I was taking it. however,
In this case, there was a problem in that the digital circuit chip 5 and the analog circuit chip 6 had to be manufactured independently from the whole chip, resulting in a high cost. In addition, although the digital circuit and analog circuit operate normally when they are on independent chips 5 and 6, when they are integrated on the same chip, noise causes the circuit to malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor integrated circuit which solves the above-mentioned problems, makes it easy to find defective parts, and allows integration on the same chip.

[Means to solve the problem]

The configuration of the semiconductor integrated circuit of the present invention is such that the semiconductor integrated circuit has a digital circuit that processes a digital signal and an analog circuit that processes an analog signal on the same integrated circuit board. It has a selection circuit to which input/output signals of the analog circuit and input/output signals from the outside are connected, and the input/output signals of the digital circuit and the analog circuit are connected to the external input/output signal by a control signal input to the selection circuit. or connect input/output signals from
Alternatively, the present invention is characterized in that it is possible to select whether to connect the input/output signals of the digital circuit and the analog circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a semiconductor integrated circuit according to a first embodiment of the present invention.

In FIG. 1, parts in this embodiment that have the same functions as those in the conventional example are given the same numbers.

The overall chip 1 includes a digital circuit 2 and an analog circuit 3, and the input/output wiring 23 and 24 of the digital circuit 2 are as follows.
Via the selection circuit 4, by the input/output wiring 33.34,
It is connected to external wiring 16.degree. 17 via analog circuit 3 or input/output wiring 41,42.

Next, the operation will be explained. When the normal state connection control signal is input from the control signal input 15, the internal output signal 23 and internal input signal 24 of the digital circuit 2 are output to the selection circuit 4.
The chip 1 is connected to the analog circuit 3 through wirings 33 and 34, and the entire chip 1 operates normally.

When the test state connection control signal is input from the control signal human power 15, the internal output signal 23 and internal input signal 24 of the digital circuit 2 are sent via the selection circuit 4 to one of the wirings 41 and 42 connected to the external terminal. through the external wiring 18.1
Connected to 7. At the same time, the digital signal 33 that is input to the analog circuit 3 and the digital signal 34 that is output from the analog circuit are passed through the selection circuit 4, through part of the wiring 41, 42 connected to the external terminal, and through the external wiring 16.
Connected to 17. This allows the digital circuit 2 and analog circuit 3 to be tested independently during the test state.

FIG. 2 is a block diagram of a semiconductor integrated circuit according to a second embodiment of the present invention. In FIG. 2, in this embodiment, the first
In the embodiment described above, the signal passing through the digital circuit 2 and the analog circuit 3 was a digital signal, but by incorporating the A/D converter 28 and the D/A converter 27 in the digital circuit 2 side, a digital Circuit 2 and analog circuit 3
The signal passed through is an analog signal. Therefore, when the control signal 15 indicates the normal operating state, the analog signal 23 output from the digital circuit 2 or the analog signal 26 input to the digital circuit 2 is
via the wiring 35 or wiring 36 of the analog circuit 3.
is connected to the normal state. On the other hand, when the control signal 15 indicates the test state, the output analog signal 25 and the output digital signal 23 from the digital circuit 2 are output to a part of the digital output wiring 42 and the analog output wiring 45 via the selection circuit 4. , the input analog signal 26 and the input digital signal 24 to the digital circuit 2 are connected to a part of the digital input wiring 41 and the analog input wiring 44 via the selection circuit 4.

FIG. 5 is a block diagram in which the analog circuit of FIG. 1 (or FIG. 2) is constructed of individual components outside the chip in case there is a problem with the characteristics of the analog circuit.

In FIG. 5, in this example, an analog circuit 7 consisting of individual components includes an analog output cuff 3. Analog human cuff 4. Digital output cuff 2. An analog output cuff 1 is connected, and the rest is the same as in FIG. 1 (or FIG. 2).

〔Effect of the invention〕

As explained above, the present invention provides a selection circuit between the digital circuit and the analog circuit in a semiconductor integrated circuit in which digital circuits and analog circuits coexist, and selects each input/output signal from the other's input/output signal. Since you can select whether to connect or connect to an external terminal, you can now test the digital circuit and analog circuit independently. There is no need to make separate chips and check their operation, making it easy to test digital and analog circuits, especially when there are problems with the characteristics of the analog circuit.
As shown in FIG. 5, by configuring the analog circuit 7 from individual parts, there is also the effect that the entire chip 1 can be used as a digital circuit and the required amount of characteristic improvement of the individual circuits of the analog circuit can be estimated.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a semiconductor integrated circuit according to a first embodiment of the present invention, FIG. 2 is a block diagram of a second embodiment of the present invention,
FIG. 3 is a block diagram showing a conventional example, FIG. 4 is a block diagram explaining the problems of the conventional example shown in FIG. 3, and FIG. 5 is a block diagram explaining the effects of FIG. 1 or 2. It is. 1... Whole chip, 2... Digital circuit, 3...
Analog circuit, 4... Selection circuit, 5... Digital chip, 6... Analog chip, 7... Individual component analog circuit, 11... Entire chip digital input, 12.
... Entire chip digital output, 13... Entire chip analog output, 14... Entire chip analog input, 15
... Entire chip control signal input, 16... Entire chip test digital input, 17... Entire chip test digital circuit 2 side power, 18... Entire chip test analog input, 19...
・Whole chip test analog output, 21...Digital circuit external input, 22...Digital circuit external output, 23.
... Digital circuit internal digital output, 24... Digital circuit internal digital input, 25... Digital circuit internal analog output, 26... Digital circuit internal analog input, 31... Analog circuit external analog output, 32.
... Analog circuit external analog input, 33... Analog circuit internal digital input, 34... Analog circuit internal digital output, 35... Analog circuit built-in D/A converter, 36... Analog circuit built-in A/ D converter, 41・
...Selection circuit external digital input, 42...Selection circuit external digital output, 43...Selection circuit control signal input, 4
4... Selection circuit external analog input, 45... Selection circuit external analog output, 71... Individual component analog circuit digital input, 72... Individual component analog circuit digital output, 73... Individual component analog circuit Analog output, 74...Individual component analog circuit analog input.

Claims (1)

[Claims] In a semiconductor integrated circuit having a digital circuit that processes digital signals and an analog circuit that processes analog signals on the same integrated circuit board, input/output signals of the digital circuit, input/output signals of the analog circuit, and external input/output signals are provided. a selection circuit connected to an output signal, and depending on a control signal input to the selection circuit, the input/output signals of the digital circuit and the analog circuit are connected to the input/output signal from the outside; A semiconductor integrated circuit characterized in that it is possible to select whether input/output signals of a digital circuit and the analog circuit are connected to each other.