This application note discusses how to create projects that use temperature as a variable in Microwave Office (MWO) and Analog Office (AO) simulations. This document includes:
A brief discussion of how the built-in variables _TEMP and _TEMPK are used.
References to a project used to illustrate the main points of this application note. Click the button below to open the project.
Introduction
Temperature controls the noise generation processes and the static operating point of nonlinear components and their dynamic behavior. With the necessary models for these components it is possible to calculate the DC operating point, noise figure, and both AC small and large signal properties of components as a function of temperature.
The AWR Design Environment uses two built-in variables _TEMP and _TEMPK, and functions such as ctok(x) and ktoc(x) to assist a designer in setting up projects to perform temperature sensitive simulations.
TEMP is a built-in variable in the AWR Design Environment intended for models that have a specific temperature parameter. _TEMP uses the units specified as global units (choose Options > Project Options and click the Global Units tab to select degree Kelvin, degree Celsius or degree Fahrenheit as the global units. The default value of this variable can be overwritten using an equation; for example the equation "_TEMP = 30"sets this global variable to 30 degrees Celsius if these are the set units.
_TEMPK is in degrees Kelvin and retains these units regardless of the global units setting. This variable is used to adjust the temperature for models without a temperature parameter. This variable only affects noise simulation of linear elements.
You can use both _TEMP and _TEMPK in equations to define the operating temperature of components. You can use equations to tie both linear and nonlinear temperature to the same value, and to assign one temperature value to all elements through hierarchy. Also, you can assign different temperatures to passive circuits, small signal amplifiers, Power Amplifier drivers and Power Amplifiers with a global temperature being used to define the base-plate or housing temperature, and equations added to define the unique temperatures of the high temperature components using dissipation and thermal resistance calculations.
Displaying Temperature Values Used in Simulation
Different Temperature Situations in AWR
Temperature and Noise for Passive Structures
Temperature and Active Device Operation
Temperature and Active Device Operation with a Device Defined by a SPICE Netlist
How to Sweep Passive and Active Temperature Through Hierarchy
Group Design Issues
Conclusions
The AWR Design Environment supports several methods to define and manipulate the temperature of electronic devices, and therefore to enable comprehensive simulation of noise processes, device operating point parameters such as gain and full nonlinear behavior.
This application note has illustrated the methods that can be employed to perform noise and nonlinear simulations when the operating temperature needs to be accounted for.