JPH04113672A - Master slice type semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To eliminate necessity of connecting a correcting circuit to an exterior and to provide an economical effect by inserting other wiring in parallel with wirings for coupling between a R-string circuit and a reference voltage input terminal through a transfer gate. CONSTITUTION:In a master slice type semiconductor integrated circuit containing a D/A converter 2 including an R-string circuit 21, other wiring is inserted in parallel with wirings for coupling between the circuit 21 and an upper reference voltage input terminal 3 through a transfer gate, i.e., a P-channel transistor 6. Then, if wiring is actually conducted to become a higher wiring resistance value than an expected one, an input signal of a low level is input to a gate input terminal 4. Thus, a P-channel transistor 6 is turned ON, ON resistances of a wiring resistor 12 and the transistor 6 are connected in parallel, and an actual resistance value is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a master slice type semiconductor accumulation circuit, and in particular to a DA (or A-D) including an R-string circuit.
> Used in master slice type semiconductor integrated circuits with built-in conversion circuits.

[Conventional technology]

In recent years, significant advances in CAD technology have led to automation of the design of semiconductor integrated circuits, and in the gate array method, which is a typical example of the master slice method, upper wiring patterns are now automatically created using computer processing. .

This type of gate array type semiconductor integrated circuit can be automatically wired, but if another circuit containing the same macro is wired, the wiring pattern will change, and the resulting fluctuation in wiring resistance will be caused by D-A Because it affected the accuracy of the conversion circuit, it was necessary to devise a layout to reduce fluctuations or to connect an external correction circuit.

FIG. 2 is a block diagram showing a master slice type semiconductor integrated circuit incorporating a conventional DA conversion circuit.

The DA conversion circuit 2A is an R-string type DA conversion circuit, and is an R-string circuit 21A in which a large number of resistors are connected in series.
have. A wiring resistance 10A exists between the most significant bit resistance 7A of the R-string circuit 21A and the upper reference voltage input terminal 3A. If this wiring resistance of 10 A is constant, the value of the resistor of 7 A can be set in anticipation of it in advance, but with the master slice method, the wiring pattern changes depending on the product, making it difficult to realize a high-performance D-A conversion circuit. I can't.

[Problem to be solved by the invention]

The D-A conversion circuit in the conventional master slice semiconductor integrated circuit described above requires an external correction circuit to be connected in order to compensate for variations in wiring resistance etc. that occur due to the use of the master slice method. It had the disadvantage that it could not be designed economically.

[Means to solve the problem]

The present invention provides a D-A (or A-
D) In a master slice type semiconductor integrated circuit incorporating a conversion circuit, another wiring is inserted in parallel with the wiring connecting the R-string circuit and the reference voltage input terminal via a transmission gate. It is.

〔Example〕

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

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

This embodiment is implemented in a master slice type semiconductor integrated circuit incorporating a D-A converter circuit 2 including an R-string circuit 21, in parallel with the wiring connecting the R-string circuit 21 and the upper reference voltage input terminal 3. Another wiring is inserted through the transmission gate (P channel transistor 6).

If we consider the resistor 7 of the most significant bit to be illusory,
The actual most significant bit resistance is considered to be 7 plus wiring resistance 10. Therefore, in consideration of variations in wiring resistance, the resistance value, which is the sum of 7 and 10, is set to be slightly lower than the expected resistance value (that is, the typical value). Therefore, if wiring is actually performed and the resistance value is higher than expected, by inputting a low-level input signal to the gate input terminal 4, the P-channel transistor 6 is turned on, and the wiring resistance 10 becomes The wiring resistance 12 and the on-resistance of the P-channel transistor 6 are connected in parallel, and the actual resistance value becomes low. In this way, trimming becomes possible, and the range of actual resistance fluctuation of the most significant bit can be reduced.

Although the case in which a D-A conversion circuit is incorporated has been described above, it is clear that the present invention can be applied to an A-D conversion circuit having an R-string circuit.

〔Effect of the invention〕

As explained above, the present invention enables resistance trimming by inserting another wire in parallel with the wire connecting the R-string circuit and the reference voltage input terminal via the transmission gate. When performing full scale adjustment of the -A (or A-D) conversion circuit, it is not necessary to connect external elements, the number of parts is reduced, and there is an effect that it can be made more economical. In addition, from a different perspective, it is also possible to control voltage fluctuation adjustment using digital signals, which has the effect of easily achieving high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1, IA...Semiconductor integrated circuit, 2, 2A...D-A converter, 21...R-string circuit, 22...Digital input line, 23...Analog output line, 24...
Selection section, 3, 3A...Upper reference voltage input terminal, 4...
・P-channel transistor gate input terminal, 55A・
. . . Lower reference voltage input terminal, 6 . . P channel transistor, 7 . . . Resistance of the most significant bit of the R-string circuit, 10. IOA, 11. IIA...Wiring resistance.

Claims (1)

[Claims] In a master slice type semiconductor integrated circuit incorporating a D-A (or A-D) conversion circuit including an R-string circuit, another wire is connected in parallel with the wiring connecting the R-string circuit and the reference voltage input terminal. A master slice type semiconductor integrated circuit characterized in that wiring is inserted through a transmission gate.