ElectricalAmplifierTimeStepper

class photonforge.ElectricalAmplifierTimeStepper(*, gain=0, f_3dB=None, saturation_power=None, compression_power=None, ip3=None, noise_figure=None, r0=0, r1=0, ports=None, seed=None)

Time-stepper for a broadband amplifier or modulator dirver.

This model implements an electrical amplifier with linear gain, noise, bandwidth limiting, port reflections, and common nonlinear effects: 1 dB compression, third-order intercept point (IP3), and saturation.

Parameters:

• gain (Annotated[float, units='dB']) – The amplifier’s power gain.

• f_3dB (Annotated[Annotated[float, minimum=0, units='Hz'] | None, _]) – -3 dB frequency cutoff for bandwidth limiting.

• saturation_power (Annotated[float, units='dBm'] | None) – Output saturation power.

• compression_power (Annotated[float, units='dBm'] | None) – 1 dB compression power.

• ip3 (Annotated[Annotated[float, units='dBm'] | None, _]) – Third order intercept point.

• noise_figure (Annotated[float, units='dB'] | None) – The amplifier’s noise figure (NF). If None, noise is disabled.

• r0 (Annotated[float, maximum=1, minimum=-1]) – Reflection coefficient for the input port.

• r1 (Annotated[float, maximum=1, minimum=-1]) – Reflection coefficient for the output port.

• ports (Annotated[Sequence[str], maxItems=2, minItems=2] | None) – Input and output port names. If not set, the sorted list of port names from the component is used.

• seed (Annotated[int, minimum=0] | None) – Random number generator seed to ensure reproducibility.

Notes

The forward path signal is processed through the following stages at each time step:

1. Low-pass filter for bandwidth limiting:

   \[ \begin{align}\begin{aligned}y_0\![n] &= \alpha y_0\![n-1] + (1-\alpha) G_a a_\text{in}\\\alpha &= e^{-2\pi f_\text{3dB} \Delta t}\\G_a &= 10^\frac{G_\text{dB}}{20}\end{aligned}\end{align} \]

2. Soft-knee compression:

   \[ \begin{align}\begin{aligned}y_1 &= y_0 \left( 1 + \frac{c_s}{P_\text{1dB}} y_0^2 \right)^{-\frac{1}{2}}\\c_s &= 10^\frac{1}{10} - 1\end{aligned}\end{align} \]

3. Cubic IP3 nonlinearity:

   \[y_2 = y_1 \left(1 - \frac{1}{P_\text{IP3}} y_1^2\right)\]

4. Smooth saturation: A tanh function smoothly clamps the output amplitude to approach \(\sqrt{P_\text{sat}}\).

5. Additive noise: if enabled, white Gaussian noise is added to the output. The noise power spectral density is derived from the noise figure \(F\) as \(S_P = k_B T_0 G_\text{dB} F\).

Methods

reset()	Reset internal state.
setup(component, time_step, *[, ...])	Initialize the time stepper.
setup_state(*, component, time_step, **kwargs)	Initialize internal state.
step([inputs, steps, time_step, show_progress])	Compute the outputs of this time stepper, given inputs.
step_single(inputs, outputs, time_index, ...)	Take a single time step on the given inputs.
update(*args, **kwargs)	Update this time stepper.

Attributes

parametric_function	Function used to update the time stepper.
parametric_kwargs	Keyword arguments used to update the time stepper.
properties	Object properties.
random_variables	Random variables associated to the time stepper's parameters.

reset()

Reset internal state.

setup_state(*, component, time_step, **kwargs)

Initialize internal state.

Parameters:

• component (Component) – Component representing the amplifier.

• time_step (Annotated[float, minimum=0, units='s']) – The interval between time steps (in seconds).

• kwargs – Unused.

step_single(inputs, outputs, time_index, update_state, shutdown)

Take a single time step on the given inputs.

Parameters:

• inputs (ndarray) – Input values at the current time step. Must be a 1D array of complex values ordered according to keys.

• outputs (ndarray) – Pre-allocated output array where results will be stored. Same size and type as inputs.

• time_index (int) – Time series index for the current input.

• update_state (bool) – Whether to update the internal stepper state.

• shutdown (bool) – Whether this is the last call to the single stepping function for the provided TimeSeries.

Return type:

None