Devices

class RappAmplifier(a_sat: float, l: int = 2, g_ss: float = 1, name: str = 'Rapp Amplifier')

A class representing a Solid State Power Amplifier with nonlinear characteristics.

Signal Model

The general form of the Rapp input-output relationship can be used for memoryless nonlinearity and it is described by [1, 4.45]:

\[y[n] = g \left( 1 + \left( \frac{|x[n]|}{a_\mathrm{sat}} \right)^{2l} \right)^{-\frac{1}{2l}} x[n]\]

where:

• \(A_{\text{sat}}\) is the input saturation value,

• \(l\) is the Magnitude smoothness factor,

• \(g\) is the small-signal gain,

Attributes

a_satfloat

The input saturation value.

lint, optional

The magnitude smoothness factor (default: 2).

g_ssfloat, optional

The small-signal gain (default is 1).

namestr, optional

The name of the amplifier (default is “Rapp Amplifier”).

References

• Ghannouchi, Fadhel M., Oualid Hammi, and Mohamed Helaoui. Behavioral modeling and predistortion of wideband wireless transmitters. John Wiley & Sons, 2015.

class SalehAmplifier(a_sat: float = 1, alpha_am: float = 1.9638, beta_am: float = 0.9945, alpha_pm: float = 2.5293, beta_pm: float = 2.8168, name: str = 'Saleh Amplifier')

A class representing a Saleh model of a Traveling Wave Tube Amplifier (TWTA).

This model characterizes the nonlinear behavior of a TWTA. This includes both AM/AM and AM/PM conversions.

Signal Model

The conversions are defined as:

\[y[n] = x[n] \cdot G(x[n]) e^{j \Phi(x[n])}\]

• AM/AM Conversion:

\[G(x) = \frac{\alpha_a }{1 + \beta_a \frac{|x|^2}{V_{sat}^2}}\]

• AM/PM Conversion:

\[\Phi(x) = \frac{\alpha_{\phi} \cdot \frac{|x|^2}{V_{sat}^2}}{1 + \beta_{\phi} \cdot \frac{|x|^2}{V_{sat}^2}}\]

Attributes

a_satfloat, optional

The input saturation value (default is 1).

alpha_amfloat, optional

The AM/AM conversion parameter (default is 1.9638).

beta_amfloat, optional

The AM/AM conversion parameter (default is 0.9945).

alpha_pmfloat, optional

The AM/PM conversion parameter (default is 2.5293).

beta_pmfloat, optional

The AM/PM conversion parameter (default is 2.8168).

namestr, optional

The name of the amplifier (default is “Saleh Amplifier”).