JPH05274384A - Method for designing analog circuit - Google Patents

Abstract

PURPOSE:To permit an unskilled designer to easily design analog circuits by means of CAD computers and circuit simulators. CONSTITUTION:The CAD computer is provided with a circuit library section a recording design data in having been designing analog circuits and a design knowledge storage section B recording memory data to be referred to in using the circuit simulator. First, input data consisting of the type of analog circuits to be designed and request characteristic or the like is inputted, reading out the optimum design data to decide the distribution of the analog circuit. The distribution data and the required memory data recorded on a design knowledge storage section B are externally outputted. By means of the circuit simulator, the optimum element value satisfying the request characteristic is decided. Then the distribution data of analog circuit and the data of the optimum element value are stored in the circuit library section. On the other hand, the memory data which has been obtained in the process of the designing is stored in a knowledge storage section B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for designing an analog circuit using a CAD computer or a circuit simulator.

[0002]

2. Description of the Related Art Since a digital circuit takes a signal value of 0 or 1, its operation description is simple and its description format is being standardized. Therefore, the technology of automatically designing a digital circuit by algorithmic processing has been developed and put into practical use, the design period has been further shortened, and anyone can easily design a digital circuit by mastering the operation technology format. It has become.

On the other hand, the automatic design of analog circuits has not reached the stage of practical use. That is, since the analog circuit has various functions and its operation is complicated, it is difficult to describe the operation unlike the digital circuit. In part,
Although there is a movement to consider the description format, there is no prospect of standardization. Moreover, even if the analog circuit is functionally the same circuit, the element values forming the wiring and the circuit are different due to the difference in the circuit characteristics, so only the algorithmic processing like the digital circuit,
It is difficult to automatically design an analog circuit.

Therefore, at present, analog circuits are manually designed by using tools such as a circuit diagram editor and a circuit simulator as an auxiliary.

[0005]

However, there is a drawback in that an analog circuit can be designed only by a person who is familiar with the circuit theory and who has mastered the characteristics and usage of the tool. In addition, it takes time to learn circuit theory, etc., and since the analog circuit design procedure has not been standardized, it is difficult for young designers to pass on the knowledge held by skilled designers. It is not easy to train people.

The present invention was created in view of the above background, and an object of the present invention is to provide a method of designing an analog circuit which enables even an inexperienced designer to easily design a circuit. To provide.

[0007]

A method of designing an analog circuit according to the present invention is a method of designing an analog circuit by using a CAD computer or a circuit simulator.
In the memory of the CAD computer, design data when an analog circuit is designed in the past is recorded in advance for each type of circuit. While this database is used as a circuit library section, at least a circuit simulator is also stored. Memo data that is useful for use is recorded in advance. When this database is used as the design knowledge case, first, input data including the type of analog circuit to be designed, required characteristics, etc. is input to the CAD computer. And CAD
Using a computer for searching the circuit library section based on the input data, after reading the optimum design data, determine the wiring of the analog circuit of the type indicated by the input data with reference to the design data, The data of the determined analog circuit wiring and the necessary memo data recorded in the design knowledge section are externally output, and the data of the determined analog circuit wiring and the initial setting values of the elements constituting the analog circuit are circuited. Input the values to the simulators respectively, use the circuit simulator to find the characteristics of the initialized analog circuit, repeat this with the values of the elements as variables, and determine the optimum element values that satisfy the required characteristics indicated by the input data. Then, the wiring data of this analog circuit and the data of the optimum element value are used as design data in the circuit library section. Characterized in that so as to respectively stored in the knowledge storage section notes data obtained in the course of performing the round design.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the analog circuit designing method of the present invention will be described below with reference to the drawings. Here, an example of designing not only an analog circuit using a CAD computer and a circuit simulator but also a mask pattern of an integrated circuit using an analog circuit layout tool will be described. FIG. 1 is a view for explaining the embodiment method, and mainly shows a flowchart.

First, a user (designer) inputs input data of an analog circuit to be designed into a CAD computer. Here, the input data is the type and required characteristics of the analog circuit to be designed. Taking the types of circuits as examples, there are A / D conversion circuits, D / A conversion circuits, filters, operational amplifiers, amplification circuits, arithmetic circuits, oscillation circuits, power supply circuits, etc. Taking required characteristics as an example, area, There are power consumption, input / output voltage range, gain, etc. These input data can be input to the CAD computer in a designated format (S1).

By the way, in a predetermined memory of a CAD computer, design data used when an analog circuit is designed in the past is recorded in advance for each type of circuit. This database is used as the circuit library section α. Here, design data is a data group consisting of circuit features, applications, wiring (netlist), element values, circuit characteristics, etc.
There are as many types of circuits as there are. Note that FIG. 2 shows a configuration example of the circuit library, and FIG. 3 shows an example of data of the one-stage amplifier circuit registered in the circuit library.

Further, memo data, which is useful for utilizing the circuit simulator and the analog circuit layout tool, is recorded in advance in a predetermined memory of the CAD computer, and this database is used as the design knowledge case part β. Here, memo data is data related to knowledge of circuit simulators and analog circuit layout tools, know-how about circuits accumulated by experienced analog circuit designers in the past when they designed circuits, and analog circuit layout tools. There are data related to the history when layout is performed in the past. These memo data are stored in a ruled form.

When the above input data is input,
The CAD computer carries out the following processing. First, the circuit library section α is searched based on the input data, and the optimum design data is read. That is, design data that is the same as the type of circuit indicated by the input data and that also has the closest required characteristics is selected from the circuit library section α (S2).

Then, the netlist of the analog circuit to be designed is determined based on the data of the netlist constituting the selected design data, and this netlist is externally output on the circuit diagram editor attached to the CAD computer. ..
If necessary, the memo data recorded in the design knowledge section β is also output to the outside (S3).

When the automatically selected design data needs to be changed, the data of the knowledge about the change of the selection range recorded in the design knowledge case section β is displayed externally, and the designer can refer to the data to change the data. Design data is specified.

Further, when a part of the displayed netlist needs to be changed, the user operates the CAD computer to make a change by referring to the data of the knowledge about the circuit change recorded in the design knowledge case section β.

Further, when there is no optimum design data in the circuit library α, the user inputs the netlist data of the new circuit to the CAD computer by referring to the knowledge data about the circuit change recorded in the design knowledge case β. input.

When the netlist of the analog circuit is determined, the data of this netlist is transferred to the circuit simulator. Then, the user inputs the data of the initial setting values such as the approximate values of the elements forming the analog circuit and the constraint conditions to the CAD computer. This data is also transferred to the circuit simulator. At this time, the data of the knowledge about the initial setting recorded in the design knowledge case part β is displayed on the circuit diagram editor, and the initial setting is performed with reference to this. Alternatively, each element value may be initially set at random (S
4).

When the initialization of the analog circuit is completed, the circuit simulator operates and the characteristics of the analog circuit are examined. At this time, the values of the elements forming the analog circuit are used as variables to repeatedly examine the characteristics of each changed analog circuit. Then, the analog circuit having the characteristic closest to the required characteristic indicated by the input data is searched for, the value of the element forming this circuit is obtained, and the value of the element is optimized.
Here, the user can rank the importance of each item of the required characteristic, and the important item is optimized with priority. At this time, the data of the knowledge about the weighting change between the circuit characteristic items recorded in the design knowledge case β is displayed on the circuit diagram editor, and the optimization is performed with reference to this data (S5).

However, in this embodiment, not only the design of the analog circuit but also the mask pattern of the integrated circuit is designed by using the analog circuit layout tool as described below, so that the elements constituting the analog circuit are designed. The value of is kept roughly and looking at the result of the layout of the mask pattern,
Finally determine the details of the element values

When the values (rough values) of the elements forming the analog circuit are determined, this data is transferred to the analog circuit layout tool, the analog circuit layout tool operates, and the mask pattern of the integrated circuit is obtained. At this time, data relating to the history of the layout performed in the past using the analog circuit layout tool recorded in the design knowledge case β is displayed externally, and the analog circuit layout tool is operated with reference to this. Then, the element value is extracted from the mask pattern after layout, the extracted data is transferred to the circuit simulator, and the circuit simulator is operated again. By repeating this, detailed values of the elements forming the analog circuit are finally determined and optimization is performed.

After the above processing, the netlist and element values (detailed values) of the analog circuit are finally determined.
When the characteristics of this analog circuit do not satisfy the characteristics required by the user, the process returns to step 4 to change the initial setting value,
Subsequent processing is performed in the same manner as described above to bring the characteristics of the analog circuit close to the required characteristics as much as possible. This circuit is selected as the final design result (S6).

The selected design result, that is, the data of the analog circuit netlist and the optimized element values, together with the data of the type of circuit, characteristics / applications, circuit characteristics, etc.
The design data is transferred to and recorded in the circuit library α. In addition, memo data which is obtained in the process of designing this time and which serves as a reference when using the circuit simulator and the analog circuit layout tool is transferred to the design knowledge storage β and recorded in a ruled form (S7). ..

The analog circuit designing method according to the present invention is not limited to the above-described embodiment, but may be configured such that a CAD computer and a circuit simulator are separately used.

[0024]

As described above, the analog circuit designing method according to the present invention enables the data recorded in the circuit library and the design knowledge storage to be fully utilized when designing using a CAD computer or a circuit simulator. Therefore, even an inexperienced designer can easily design an analog circuit. Further, since the data in the circuit library and the design knowledge storage section are further enhanced every time the circuit is designed, there is an advantage that a high quality design can be efficiently performed as the number of times of design increases.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a method according to an embodiment of the present invention, which is mainly a flowchart.

FIG. 2 is a diagram showing a configuration example of a circuit library.

FIG. 3 is a diagram showing an example of data of a one-stage amplifier circuit registered in a circuit library.

[Explanation of symbols]

 α Circuit library β Design knowledge storage

Claims (1)

[Claims] 1. A method for designing an analog circuit by using a CAD computer or a circuit simulator, wherein design data of an analog circuit designed in the past is stored in a memory of the CAD computer for each type of circuit. In the same way, this database is used as the circuit library section, and similarly, at least memo data that is useful for using the circuit simulator is recorded in advance. First, input data including the type of analog circuit to be designed, required characteristics, etc., is input to a CAD computer, and the CAD computer is used to search the circuit library section based on the input data to obtain optimum design data. After reading, the analog circuit of the type indicated by the input data is referred to with this design data. The wiring of the determined analog circuit and the necessary memo data recorded in the design knowledge section are output to the outside, and the determined wiring of the analog circuit and the elements forming the analog circuit. Input the initial setting value of each to the circuit simulator, calculate the characteristics of the initialized analog circuit using the circuit simulator, repeat this with the value of the element as a variable, and satisfy the required characteristics indicated by the input data. The optimum element value is determined, and then the wiring data of this analog circuit and the optimum element value data are used as design data in the circuit library section,
On the other hand, a method of designing an analog circuit, characterized in that the memo data obtained in the process of designing this time is stored in the knowledge storage unit, respectively.