JP2001167140A - Simulation method for analog-digital hybrid circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for rapidly simulating an analog-digital hybrid circuit. SOLUTION: A switch part 15 is inserted between a DA converting element 14 and an analog simulator part 13 to propagate none of the signal from a logic simulator part 12 to the analog simulator part 13 until the mode of a digital circuit part is determined, and then unnecessary analog simulation execution stages are eliminated to reduce the data processing quantity of analog simulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simulating an analog / digital mixed circuit in which an analog circuit section and a digital circuit section are mixed.

[0002]

2. Description of the Related Art In recent years, with the increase in the number and functions of LSIs, mixed circuits in which analog circuits and digital circuits are mixed have been integrated into one LSI chip.・ Regarding the simulation method for digital mixed circuits, reduction of analysis time,
It is desired to improve the accuracy of simulation results.

[0003] As a simulation method of the currently mainstream analog / digital mixed circuit, there is the following method. A conventional simulation method will be described with reference to FIG. 5 showing a schematic configuration diagram of the simulator.

In FIG. 5, a circuit data 1 to be analyzed is converted into an analog circuit data 3 by a circuit information extracting unit 2.
And the digital circuit section data 4. The analog circuit section data 3 is input to the analog simulator section 6, and the digital circuit section data 4 is input to the logic simulator section 7.

Further, the synchronization / signal converter 8 is a virtual signal conversion element which is inserted into a net connecting the analog circuit and the digital circuit, and converts an analog signal and a digital signal. As the signal conversion element, an analog-to-digital conversion element (hereinafter, referred to as an AD conversion element) or a digital-to-digital conversion element is used depending on the signal propagation direction.
Whether to use an analog conversion element (hereinafter, DA conversion element (9 in FIG. 6)) is appropriately selected.

Then, a predetermined input pattern 5 prepared in advance, that is, a predetermined input signal pattern is input to the analog simulator section 6 and the logic simulator section 7, and the analog simulator section 6 analyzes the analog circuit section. The logic simulator 7 analyzes the digital circuit. These simulations are performed during a specified time interval.

The synchronization / signal conversion unit 8 converts the simulation result performed by the analog simulator unit 6 into digital conversion data and transmits the converted data to the logic simulator unit 7, and converts the simulation result performed by the logic simulator unit 7 into analog data. And the data is transmitted to the analog simulator unit 6. Then, the operation of the entire mixed circuit is analyzed while performing data conversion between the analog circuit section and the digital circuit section, and the simulation result is recorded.

Next, the concept of signal conversion and signal propagation by the synchronization / signal converter 8 will be described. As an example, FIG. 6 shows a DA converter 9 for transmitting a signal from a digital circuit section to an analog circuit section.

The signal of the logic simulation result of the digital circuit unit output from the logic simulator unit 10 is input to the DA converter 9 and converted into an analog signal by a preset threshold value. The signal is transmitted to the analog simulator unit 11. Then, the analog simulator 11 performs an analog simulation based on the converted signal.

[0010]

When circuit functions such as a mixed analog / digital circuit are integrated into one LSI, some circuit blocks operate indefinitely, while other circuit blocks operate in a steady state. The following inconveniences occur.

For example, in the case of simulating a mixed circuit including a digital circuit unit for setting an operation state by serial control, an input pattern used for the simulation is such that an input pattern for setting an operation mode is input in an initial stage of the simulation. The circuit operation of the unit is driven to shift to a stable state (steady state). Subsequently, an input pattern for operation verification is input, and a mixture of two-stage input patterns of performing a simulation of a steady state is used.

Therefore, the reason why the analog circuit section coupled to the output of the digital circuit section enters a steady state is that the operation mode setting section in which the circuit operation of the digital circuit section becomes unstable has passed and the digital circuit section has reached the steady state. This is the first time since the operation has shifted to the above operation, so that the simulation result of the analog circuit section during the operation mode setting section is often ignored.

Referring to the timing chart of FIG. 4, a conventional simulation method will be described. During an operation mode setting section 20 in which serial control data 17 for setting an operation mode of a digital circuit section is input, a simulation of an analog circuit section is performed. Are treated as unquestioned, so that the input signal 18 from other than the digital circuit section is set to a non-signal state. However, since the output signal of the digital circuit unit while the operation mode is being set is propagated to the analog circuit unit, the simulation of the analog circuit unit is also performed in the operation mode setting section 20 and differs from the non-input signal state. An output signal is output from the analog circuit unit. Since the verification data of the analog circuit section obtained by the simulation of this portion is not valid and is made unquestioned, the verification data storing this portion is wasted.

In the analog / digital mixed circuit simulator, the simulation of the analog circuit section and the simulation of the digital circuit section are performed simultaneously.
A long analysis time was required to analyze all the circuit blocks in order to perform the simulation while storing and extracting the verification data in the storage device.

The present invention solves the above problems,
An object of the present invention is to provide a method for simulating an analog / digital mixed circuit that can perform simulation in a short time.

[0016]

SUMMARY OF THE INVENTION The present invention provides a method for simulating an analog / digital mixed circuit in view of the above-mentioned problems. A digital circuit and a simulation result of the digital circuit are converted into analog conversion data. A signal conversion unit for converting, and an analog circuit unit to which the conversion data is input, and provides the conversion data of the signal conversion unit to the analog circuit unit only during operation verification;
It is a configuration that is not given at other times. With this configuration, when the operation of the input-side circuit unit (digital circuit unit) is unstable, the converted data of the signal conversion unit is not input to the output-side circuit unit (analog circuit unit). The corresponding simulation is omitted, and the simulation time of the entire mixed circuit can be reduced.

Another simulation method includes an analog circuit section, signal conversion means for converting a simulation result of the analog circuit section into digital conversion data, and a digital circuit section to which the conversion data is input. The conversion data of the signal conversion means is supplied to the digital circuit unit only at the time of operation verification, and is not supplied at other times. According to this configuration, when the operation of the input-side circuit section (analog circuit section) is unstable, the converted data of the signal conversion means is not input to the output-side circuit section (digital circuit section), resulting in an unstable operation waveform. The corresponding simulation is omitted, and the simulation time of the entire mixed circuit can be reduced.

The signal conversion element inserted between the nets connecting the analog circuit section and the digital circuit section has switching means, and a signal from one simulator to the other simulator is turned on and off by the switching means. Control the propagation of When one of the simulations is in the operation mode setting and the other simulation does not matter during the section, the switch is turned off.
To prevent the signal from propagating to the other simulator. Next, turn on the switch when the operation verification mode is set.
And a signal is propagated.

With this configuration, it is possible to prevent unnecessary simulations from being executed, and to speed up the simulation of the analog / digital mixed circuit.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the concept of a simulation method for an analog / digital mixed circuit according to the present invention will be described.

First, in the first simulation method,
A digital circuit unit, a signal conversion unit that converts a simulation result of the digital circuit unit into analog conversion data, and an analog circuit unit to which the conversion data is input. In this configuration, the converted data is supplied to the analog circuit unit, and is not supplied at other times. With this configuration, when the operation of the input-side circuit unit (digital circuit unit) is unstable, the converted data of the signal conversion unit is not input to the output-side circuit unit (analog circuit unit). The corresponding simulation is omitted, and the simulation time of the entire mixed circuit can be reduced.

In the second simulation method,
An analog circuit unit, a signal conversion unit that converts a simulation result of the analog circuit unit into digital conversion data, and a digital circuit unit to which the conversion data is input. The conversion data is provided to the digital circuit unit, and is not provided at other times. According to this configuration, when the operation of the input-side circuit section (analog circuit section) is unstable, the converted data of the signal conversion means is not input to the output-side circuit section (digital circuit section), resulting in an unstable operation waveform. The corresponding simulation is omitted, and the simulation time of the entire mixed circuit can be reduced.

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

FIGS. 1 and 2 are block diagrams showing an operation concept of a simulation method of an analog / digital mixed circuit according to an embodiment of the present invention. As shown in FIG. 1, a DA converter 14 as a signal converter is connected to the output of the logic simulator unit 12 and the DA converter 1
4 is inputted to the analog simulator 13 via the switch 15. The switch unit 15 has a D
It controls whether or not the output of the A conversion element 14 is given to the analog simulator unit 13. However, the function of the DA converter 14 may be turned ON / OFF while the output of the DA converter 14 is connected to the analog simulator unit and the output of the DA converter 14 is connected to the analog simulator unit 13.

FIG. 2 shows a state in which a control signal is applied to the switch terminal 16 of the switch unit 15 and a conversion signal (conversion data) of the DA conversion element 14 is input to the analog simulator unit 13. is there.

Next, the simulation operation will be described with reference to the simulation results shown in FIG.

FIG. 3 is a timing chart simulating an analog / digital mixed circuit having a serial control circuit block in a digital circuit section. The horizontal axis represents time, and the vertical axis represents amplitude.

First, during the operation mode setting section 20, the digital circuit section is driven by the input of the serial control data 17 so that the circuit becomes stable. On the other hand, the result simulated by the logic simulator unit 12 is always converted into a continuous analog signal by a predetermined threshold value in the DA converter 14.
However, during the operation mode setting period 20, the switch 15
Is turned off to prevent signals from being propagated to the analog simulator section 13. Then, the analog simulator 13 executes an analog simulation in a no-signal state, and the analog circuit section in the operation mode setting section 20 outputs an analog signal of a certain level.

Subsequently, the serial control data 17
A predetermined control voltage is applied to the switch terminal 16 in accordance with the timing at which the operation mode setting section 20 in which is input is completed and the operation mode shifts to the operation mode verification section 21. Then, the switch unit 15 is turned on as shown in FIG.
The signal from the conversion element 14 is supplied to the analog simulator 13
And a simulation of the analog circuit section is executed.

As described above, in the simulation method of the present invention, the signal from the logic simulator 12 to the analog simulator 13 is cut off in the operation mode setting section 20 in which the operation of the logic simulator 12 is undefined. In addition, unnecessary analog simulation is prevented from being executed, and the amount of data processing in the analog simulator unit 13 is reduced. As a result, the speed of simulation of an analog / digital mixed circuit is increased.

In the above description, the digital circuit section is arranged on the input side and the analog circuit section is arranged on the output side. Conversely, the analog circuit section is arranged on the input side and the output side is arranged. In the case where the digital circuit part is
It goes without saying that the same can be said. For example, in the case of an analog circuit section having a time constant circuit including a capacitance element, the analog circuit section is transiently unstable from when the power supply voltage is turned on until the analog circuit section enters a steady state in which the analog circuit section normally functions. Although it takes some time to reach the steady state, the output of the analog circuit section is not applied to the digital circuit section during this period, and the data processing amount of the digital simulator section is reduced. The speed of the simulator of the digital mixed circuit can be increased. Also,
Even if the time constant circuit does not exist in the analog circuit section, if the number of transistors constituting the analog circuit section increases,
The same is problematic and can be improved as well.

[0032]

As described above, according to the present invention, an unnecessary simulation execution process is deleted in order to cut off signal propagation to other circuit units until the operation mode of a certain circuit block is determined. This can speed up the simulation of the analog / digital mixed circuit.

[Brief description of the drawings]

FIG. 1 is an operation conceptual block diagram (switch OFF) for describing a simulation method according to an embodiment of the present invention.
Time)

FIG. 2 is an operation conceptual block diagram (switch ON) for describing a simulation method according to the embodiment of the present invention;
Time)

FIG. 3 is a timing chart of the simulation result of FIG. 2;

FIG. 4 is a timing chart of a simulation result of a conventional example.

FIG. 5 is a schematic configuration diagram of a conventional simulator.

FIG. 6 is a conventional operation conceptual block diagram.

[Explanation of symbols]

 1 Circuit Data 2 Circuit Information Extraction Unit 3 Analog Circuit Unit Data 4 Digital Circuit Unit Data 5 Input Pattern 6 Analog Simulator Unit 7 Logic Simulator Unit 8 Synchronization / Signal Conversion Unit 12 Logic Simulator Unit 13 Analog Simulator Unit 14 DA Conversion Element 15 Switch Unit 16 Switch terminal

Continuation of the front page F term (reference) 2G032 AA01 AA09 AC08 5B046 AA08 BA03 JA04 JA05 9A001 BB04 BB05 EE05 HH32 KK31 KK37 LL05

Claims (4)

[Claims] A digital circuit unit, a signal conversion unit that converts a simulation result of the digital circuit unit into analog conversion data, and an analog circuit unit to which the conversion data is input. A method for simulating an analog / digital mixed circuit, wherein the conversion data of the signal conversion means is supplied to an analog circuit unit and not supplied at other times. 2. An analog circuit section, a signal conversion means for converting a simulation result of the analog circuit section into digital conversion data, and a digital circuit section to which the conversion data is input, wherein only when the operation is verified, A method for simulating an analog / digital mixed circuit, wherein the conversion data of the signal conversion means is supplied to the digital circuit unit and not supplied at other times. 3. A mixed circuit including an analog circuit section and a digital circuit section, and signal conversion means having switch means inserted between the analog circuit section and the digital circuit section,
A method of simulating the analog circuit and the digital circuit, wherein when the switch means is ON, a simulation result of one circuit part is transmitted to the other circuit part, and when the switch means is OFF, the simulation is performed. A method of simulating an analog / digital mixed circuit, wherein a result is not propagated to the other circuit section. 4. The switch device according to claim 3, wherein said switch device has a terminal portion, and ON / OFF of said switch device is controlled by a signal applied to said terminal portion.
A simulation method for the described analog / digital mixed circuit.