JPH05251565A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To make it possible to directly access an arbitrary logic circuit within a semiconductor integrated circuit from the outside by causing a measuring pad, which allows a logic circuit within a semiconductor integrated circuit to be directly accessed from the outside, to function as a function block. CONSTITUTION:When an electric potential at an L level is inputted to a control terminal 12, an N-type MOS transistor 20 enters an OFF state, whilst an N-type MOS transistor 21 enters an ON state. A signal path is established between an I/O terminal 10 and an I/O terminal 11. Meanwhile, when an electric potential at an H level is inputted to the control terminal 12, the N-type MOS transistor 20 enters an ON state, whereas the N-type MOS transistor 21 enters an OFF state. Thereupon, the signal path between the I/O terminals 10 and 11 is interrupted, and a signal path is established between a measuring pad 1 and the I/O terminal 10. This makes it possible to access a function block under test connected to the I/O terminal 10 from the outside via the measuring pad 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to semiconductor integrated circuits, and more particularly,
The present invention relates to semi-custom semiconductor integrated circuits such as standard cells and gate arrays.

[0002]

2. Description of the Related Art Conventionally, this type of semiconductor integrated circuit does not have a measurement pad as a functional block for directly accessing a logic circuit inside the semiconductor integrated circuit from the outside.

[0003]

Since the conventional semiconductor integrated circuit described above does not have a measurement pad as a functional block for directly accessing the logic circuit inside the semiconductor integrated circuit, it is possible to apply a potential from the outside or a potential. Has the drawback that it is difficult to measure.

[0004]

A semiconductor integrated circuit according to the present invention has a measurement pad as a functional block for directly accessing a logic circuit inside the semiconductor integrated circuit from the outside.

[0005]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. The measurement pad 1 is a measurement pad for applying a potential from the outside of the semiconductor integrated circuit chip including this circuit or measuring the potential. The input / output terminal 10 is a terminal for connecting a measured functional block that applies a potential through the measurement pad 1 or measures the potential, and the input / output terminal 11 is a terminal for connecting the measured functional block to another functional block during normal operation. It is a terminal. The control terminal 12 is a terminal for controlling whether or not an access is made from the outside through the measurement pad 1.

When an L-level potential is input to the control terminal 12, the N-type MOS transistor 20 is turned off and the N-type MOS transistor 20 is turned off.
The transistor 21 is turned on and a signal path is formed between the input / output terminal 10 and the input / output terminal 11. On the other hand, when an H level potential is input to the control terminal 12, the N-type MOS transistor 20 is turned on and the N-type MOS transistor 21 is turned on.
Is turned off, the signal path between the input / output terminals 10 and 11 is cut off, a signal path is formed between the measurement pad 1 and the input / output terminal 10, and is externally connected to the input / output terminal 10 through the measurement pad 1. It is possible to access the measured function block.

FIG. 2 is a block diagram showing an example of use of the present invention. By inserting the circuit shown in FIG. 1 between the functional block (1) 101 and the functional block (2) 102, the functional block (1) 101 (or the functional block (2) 102 is responsive to the control signal from the control terminal 12. ) To the functional block (2) 102 (or the functional block (1) 10
It is possible to select whether to propagate the signal to 1) or to directly access the functional block (2) 102 from outside the semiconductor integrated circuit chip.

[0008]

As described above, according to the present invention, the measurement pad for directly accessing the logic circuit inside the semiconductor integrated circuit from the outside is provided as a functional block. By inserting the measurement pad block, an arbitrary logic circuit inside the semiconductor integrated circuit can be directly accessed from the outside.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a usage example of the present invention.

[Explanation of symbols]

 1 Measuring Pad 10 Input / Output Terminal 11 Input / Output Terminal 12 Control Terminal 20 N-type MOS Transistor 21 N-type MOS Transistor 30 Inverter Circuit

Claims (1)

[Claims] 1. In a standard cell or gate array type semiconductor integrated circuit in which a logic circuit block having a certain function (hereinafter referred to as a functional block) is combined to construct one semiconductor device, the inside is directly external to the inside of the semiconductor integrated circuit. 2. A semiconductor integrated circuit having a measurement pad as a functional block capable of measuring the electric potential of the logic circuit and applying the electric potential.