Micro-Cap v7.1.6 / RM

SUM3

A triple summer is sometimes convenient. The desired function is:

VOut(t) = ka Va(t) + kb Vb(t)+ kc Vc(t)

This function is implemented with the SUM3 macro:

Figure 21-26 SUM3 macro equivalent circuit

The three input parameters, KA, KB, and KC, multiply each input. The three scaled input signals are then added to produce the output. This implementation is done with an NFV function source.

See the circuit SYSTEM1 for an example of the use of the SUM3 macro.

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TRIAC

This circuit is a macro model for a TRIAC. The macro equivalent circuit is as follows:

Figure 21-27 TRIAC macro equivalent circuit

The parameter definitions are as follows:

See the circuit THY1 for an example of the use of the TRIAC macro.

358 Chapter 21: Analog Behavioral Building Blocks

TRIGGER

This circuit is a macro model for a thyristor gate trigger circuit. The macro equivalent circuit is as follows:

Figure 21-28 TRIGGER macro equivalent circuit

There are no parameters for the macro.

See the circuit CONVERTER3 for an example of the use of this macro.

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TRIODE

The TRIODE is a macro model of a vacuum triode device. Its equivalent circuit is as shown below.

Figure 21-29 TRIODE macro equivalent circuit

The Triode macro is implemented with a 3/2 power function voltage-controlled current source. The K, MU, CGP, CGC, and CPC values are passed as parameters when the macro is used in a circuit.

See the circuit F4 for an example of the use of the TRIODE macro.

360 Chapter 21: Analog Behavioral Building Blocks

VCO

A voltage-controlled oscillator, or VCO, is an oscillator whose instantaneous frequency is dependent upon a time-varying voltage. The VCO macro has a voltage whose time dependence is given by:

VOut(t) = vp cos (2π ( f 0 t + kf VIn(t) dt))

0

In this form, f0 is the center frequency and kf is the frequency sensitivity in Hz/volt. This form of linear VCO is easily implemented as a macro:

Figure 21-30 VCO macro equivalent circuit

The VCO uses a nonlinear function source, which uses the output of an integrator stage to control the frequency. The input parameters specify the magnitude, center frequency, and the frequency sensitivity.

See the circuit F1 for an example of the use of this macro.

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WIDEBAND

This is a wideband model of a transformer.

Figure 21-31 WIDEBAND macro equivalent circuit

362 Chapter 21: Analog Behavioral Building Blocks

XTAL

XTAL is a macro model of a crystal. Its equivalent circuit is as shown below.

Figure 21-32 XTAL macro equivalent circuit

The XTAL macro is implemented with a standard tank circuit model for crystals.

For examples of how to use the macro, see the circuit XTAL1, which shows a crystal oscillator application.

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555

The 555 is a model of the ubiquitous 555 timer circuit. Its macro and equivalent circuit are as follows:

Figure 21-33 555 macro equivalent circuit

The 555 uses several nonlinear function sources to monitor the THRES and TRIG input voltage values. When they cross a certain threshold the sources switch to a high or low level and charge capacitors which drive the R and S inputs of a RS flip-flop. The flip-flop drives the output and an NPN which provides a discharge path. There are no input parameters.

For examples of how to use the macro, see the circuits 555MONO, which shows a monostable application, and 555ASTAB, which demonstrates how to use the 555 in an astable application.

You can change the power supply by using a .PARAM statement as follows:

.PARAM V555_VDD=<VDD value desired>

.PARAM V555_VSS=<VSS value desired>

The statement may be placed in the text area, the grid text, the User Definitions, or an appropriate text library file.

364 Chapter 21: Analog Behavioral Building Blocks

What's in this chapter

This chapter covers the parameter syntax, model statements, model parameters, and model equations used by each of the Micro-Cap analog devices.

Model statements describe the model parameters for the more complex devices.

Model parameters are the numeric values to be used in the model equations. They are obtained from model statements or binary model libraries (*.LBR).

Model equations use the numeric model parameter values in a set of mathematical equations that describe three aspects of a device's electrical behavior:

1.The static relationship between terminal currents and branch voltages.

2.Energy storage within the device.

3.Noise generation.

In the chapter that follows, each component is described in terms of:

1.The SPICE parameter and / or schematic attribute format.

2.The Model statement format (if any).

3.The Model parameters (if any).

4.The electrical model in terms of its schematic and model equations.

If the SPICE parameter format is not given, the component is available for use only in schematic circuits and not in SPICE text file circuits.

All devices have PACKAGE, COST, and POWER attributes. The PACKAGE attribute specifies the package to be used for PCB netlists. The optional COST and POWER attributes specify the cost and power contributions for the Bill of Materials report.

Features new in Micro-Cap 7

•S_PORT device

•COST, and POWER attributes.

•NLEV and GDSNOI noise parameters for MOSFETs.

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References

This chapter provides a comprehensive guide to the device models used in MC7. It does not, however, teach the principles of analog or digital simulation, or the operation of semiconductor devices. The following references provide a good introduction to these and related topics:

Circuit design:

1.Paul R. Gray, and Robert G. Meyer

Analysis and Design of Analog Integrated Circuits

Second Edition.

John Wiley and Sons, 1977, 1984

2.David A. Hodges, and Horace G. Jackson.

Analysis and Design of Digital Integrated Circuits

McGraw-Hill, 1983

3.Richard S. Muller and Theodore I. Kamins

Device Electronics for Integrated Circuits

Second Edition

John Wiley and Sons, 1977, 1986

4.Adel Sedra, Kenneth Smith

Microelectronic Circuits

FourthEdition Oxford, 1998

Analog Simulation:

5. A. Ruehli, Editor

Circuit Analysis, Simulation and Design Advances in CAD for LSI, Part 3, Vol 1

North-Holland 1986

6. J. Vlach, K. Singhal

Computer Methods for Circuit Analysis and Design

Van Nostrand Reinhold 1994

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