Amplifiers and Mixers
The Filters - <filter type> and System - <device type palettes contain two fundamentally different types of behavioral system models.
Filters, System - Amps & Mixers, and System - Mod/Demod can be classified as tops-down system models that support a tops-down system design flow where model behaviors are characterized by a small number of independent parameters such as frequency, power and load. They are often referred to as parameter-based behavioral models.
System - Data Models can be classified as bottoms-up system models that support a bottoms-up verification flow where model behaviors are extracted from a simulation (or measurement) of a transistor-level circuit. They are often referred to as data-based behavioral models.
The parameter-based behavioral models typically provide superior speed relative to the data-based behavioral models with both of these being vastly superior to a brute-force transistor-level simulation.
The data-based behavioral models ypically provide superior accuracy relative to the parameter-based behavioral models as they capture actual behaviors of implemented circuit components and not just design specifications.
The differences between parameter- and data-based behavioral models justify a palette emphasis on flow (all data-based behavioral models grouped together) rather than functionality (all amplifiers, mixers, modulators, and demodulators grouped together) and resulted in the addition of a System - Data Models palette.
The use model for parameter-based behavioral models is to simply set a series of parameters prior to using the model. The use model for data-based behavioral models is slightly more involved. For a discussion, see System Data Models.
The curve-fitting algorithm to determine the nonlinear behavior of the system mixer models is based on fitting a polynomial to the specified data where the saturation power (Psat) is calculated when the derivative of this polynomial is zero.
Pn(x) = a1*x1+a2*x2^2+a3*x^3+...
It is important to note that the coefficients a4,a6,a8,...are always zero. In only one case a2 is non-zero and that's when SOI and TOI are specified.
TOI & AM2PM
SOI & TOI
3 a2 ≠ 0
PndB & AM2PM
TOI & PndB
PndB & Psat
TOI & Psat
PndB & TOI & Psat