JPH02136755A - Estimating method for current consumption - Google Patents

Abstract

PURPOSE:To estimate the current consumption for even a large scaled digital circuit in proper accuracy by applying a logical simulation. CONSTITUTION:The circuit information of an objective circuit for the logical simulation, input information consisting of signal waveforms for the digital input, information of the motion definitions of various digital standard circuit units, and set time for starting and ending the storage for each individual standard unit during the simulation period are inputted to the logical simulator. Then, the logical simulation is performed to obtain the historical information of motions for every standard circuit unit. Next, based on the historical information of motions, the number of events generated for every standard circuit unit is extracted, and the parastic element information is obtained for every standard circuit unit based on the pattern information and the extracted rule information.If a general equation to give the consumption current per one event of the various standard circuit units is obtained beforehand and the consumption current is calculated for every standard circuit units group of the same kind in the objective circuit, the total consumption current in the objective circuit to be estimated can be calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention mainly relates to a method of estimating current consumption in a MOS digital circuit or the like.

[Conventional technology]

Generally, for estimating current consumption in this type of MOS digital circuit, methods such as (1) an estimation method using an analog circuit simulator, and (2) a rough estimation method based on manual calculation, etc. are used.

■ Estimation method using an analog circuit simulator Figure 3 is a flowchart showing the main steps of the estimation method using a circuit simulator, which includes element-level elements such as transistors in the circuit whose current consumption is to be estimated and their connection information. 21 and input information 22 such as analog signals for operating these elements, continuous or analog electrical characteristic (voltage, current) simulation such as DC analysis or transient response analysis using Kirchhoff's equation is performed. A circuit simulation is performed by inputting the data into a possible circuit simulator (S21), and result data 23 is obtained as a current consumption waveform, which is subjected to processing such as integration to obtain an estimated current consumption value (1). get.

■ Manual rough estimation method Figure 4 is a flowchart showing the main steps of the manual rough estimation method, showing the parts where the current consumption is expected to be especially large based on the circuit diagram 31 of the circuit whose current consumption is to be estimated. When manually extracting 531), estimates are made separately for parts with large current consumption and other parts.
Current consumption ■, 1. is each digital basic circuit unit (
For example, each logic gate circuit is given by Equation 11 below, so use this to estimate the part where the consumption is predicted to be large, and use an experimental method or manual calculation method to calculate the details of this part. Estimate (S32).

1,,, = f −C・V+ f −1,l−+11
However, f...Operating frequency C...Load capacity ■...Power supply voltage rva...Through current Other parts are estimated using equation (2), etc. (
S33).

1oss' = (f-de・■10th・Ten)×Number of logic gates...(2) However, T...Average operating frequency...Average I□...of through-current of load device Note that the number of logic gates in equation (2) indicates the digital basic circuit unit.

For parts with large current consumption (add the current consumption obtained using formula 11 and the current consumption for other parts obtained based on (2) 2)534), the estimated current consumption value! . , we get 3.

[Problem to be solved by the invention]

By the way, the above-mentioned method of estimating current consumption using an analog simulator can provide accurate estimates for small-scale circuits, but for medium- to large-scale circuits, as the circuit size increases, a large and high-speed computer is required, and this method is difficult to estimate. However, there was a problem in that it was not always possible to fully deal with the problem, and there were significant economic constraints.

In addition, the rough calculation method using manual calculations has problems such as poor accuracy, requiring a large amount of time to estimate, and the accuracy of the estimate widely varying depending on the technical level of the designer making the estimate.

The present invention was made in view of the above circumstances, and its purpose is to provide a method for estimating current consumption that can be processed using an economically inexpensive computer and that can estimate with appropriate accuracy. .

[Means to solve the problem]

The current consumption estimation method according to the present invention involves inputting digital circuit information and input information together with operation definition information of a DigiMole circuit unit into a logic simulator, and obtaining operation history information for each digital circuit unit, which is the obtained logic simulation result information. The current consumption is estimated based on the general formula for estimating the current consumption of each digital circuit, which is determined in advance.

[Effect]

According to the present invention, it is possible to efficiently estimate the current consumption xi with appropriate accuracy using the results of logic simulation instead of circuit simulation and the general formula for estimating current consumption for each digital circuit. becomes.

〔Example〕

The present invention will be specifically explained below based on the drawings.

FIG. 1 is a flowchart showing the main steps of the current consumption estimation method according to the present invention, and FIG. 2 is a time chart.

First, circuit information 1 of the logic simulation target circuit, input information 2 consisting of digital human input signal waveforms, and operation definition information 3 that defines the operations of various digital basic circuit units.
, logical simulation period t,. 11. The period during which the operation M history of each individual digital basic circuit unit in the circuit should be stored, that is, the memory start time Cts
), the setting time 4 of the storage end time (tl) is manually entered into the logic simulator, and t. Logic simulation was performed over 1 m1 (Sl), and Figure 2 (a), (b),
Operation history information 5 for each digital board circuit unit as shown in (c) is obtained.

Next, based on the obtained operation history information 5, the number of occurrence events 6 for each individual digital basic circuit unit in the target circuit is extracted between 1 and 11 as shown in FIG. 2 (D) (S2). .

Note that one event here refers to a state in which the unit output state of the digital basic circuit changes twice, for example, from low level to low level to low level, or from high level to low level to high level.

In addition, parasitic element information in the target circuit is determined based on pattern information 117, which is a planar configuration of the LSI in the target circuit held as a database, and extraction rule information 8 for extracting parasitic element information from the pattern information. t
1 (mainly load capacitance) (S3), and parasitic element information 9 for each individual digital basic circuit unit is obtained.

On the other hand, in advance, general formula (function of load capacity) 1 gives the current consumption per event of various basic digital circuit units.
0, for example, the general formula for an inverter (+Hv =
f +nv (C) General formula for two-person NOR circuit I2.
4°, = f-work. I (C) etc. (.

Next, the number of events for each individual digital basic circuit unit obtained earlier is 6. Based on the load capacitance 9 and the general formula 10 which gives the current consumption expressed as a function of the load capacitance, 1, -1. The current consumption during the period is calculated (S4).

The sum of the currents consumed by all the inverters (for example, n inverters) in the target circuit (11NV group) is generalized as follows (3)
It is given by Eq.

1++J'\v=Σ(number of events to inverter) f
+Hv (CI+)...(3) However, f INV
(Cm) = Current consumption per event of inverter K (K=1-n) and sum of current consumed by all two-person NOR circuits (for example, m) in the target circuit 12 The NOR group can be generalized as follows ( 4) Given by Eq.

1 gH01 group = Σ (number of events in 2NORK) ・
fzNom(Cx)...(4) However, f isog(Cm) - NOR circuit K=1
-m) Current consumption per event Similarly, for various other digital basic circuit units existing in the circuit to be estimated, each circuit has a period of 1. -1. Calculate the current consumption at .

Then, the total current consumption I O12 between 1 and -1 in the circuit to be estimated is calculated according to the following formula (5) (S5)
.

1. -1゜If there is a special circuit such as an oscillation circuit in the circuit to be estimated, perform a circuit simulation of the circuit in the same manner as the conventional method shown in Figure 3 and calculate the above-mentioned current consumption. Separately estimate the current consumption 11 (estimate values r, , l) and add these to the numerator side in (5) 2.

〔Effect of the invention〕

As described above, in the method of the present invention, logic simulation is used instead of conventional circuit simulation.
The present invention has excellent effects, such as making it possible to efficiently estimate current consumption with appropriate accuracy and with no variation in estimated values even for large-scale digital circuits.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the main steps of the method of the present invention;
FIG. 2 is a time chart, and FIG. 3.4 is a flowchart showing the main steps of the conventional current consumption estimation method. 1...Circuit information 2...Input information 3...Operation definition information of various digital basic circuit units 4...Setting time for obtaining operation history information 5...Operation history information 6
. . . Number of events for each individual digital basic circuit unit lO . . . General formula for current consumption for each individual digital basic circuit unit. In the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) Circuit information including the elements and their connection information in the target circuit for estimating current consumption including elements such as digital circuit units, digital operation definition information of each element, and digital input necessary to operate each element. A process of performing logical simulation based on the information and obtaining digital operation history information of each element, and calculating the total amount of the circuit to be estimated based on this digital operation history information and the general formula for estimating current consumption for each element obtained in advance. A method for estimating current consumption, comprising: a step of calculating an estimated value of current consumption.