Third-order Bireciprocal LWDF

Small bireciprocal lattice wave digital filter.

import numpy as np
from mplsignal.freq_plots import freqz_fir

from b_asic.core_operations import Addition, SymmetricTwoportAdaptor
from b_asic.schedule import Schedule
from b_asic.signal_flow_graph import SFG
from b_asic.signal_generator import Impulse
from b_asic.simulation import Simulation
from b_asic.special_operations import Delay, Input, Output

in0 = Input("x")
D0 = Delay(in0)
D1 = Delay()
D2 = Delay(D1)
s = SymmetricTwoportAdaptor(-0.375, in0, D2)
D1 <<= s.output(1)
a = s.output(0) + D0
out0 = Output(a, "y")

sfg = SFG(inputs=[in0], outputs=[out0], name="Third-order BLWDF")

The SFG looks like

sfg

Set latencies and execution times

sfg.set_latency_of_type(SymmetricTwoportAdaptor.type_name(), 4)
sfg.set_latency_of_type(Addition.type_name(), 1)
sfg.set_execution_time_of_type(SymmetricTwoportAdaptor.type_name(), 1)
sfg.set_execution_time_of_type(Addition.type_name(), 1)

Simulate

sim = Simulation(sfg, [Impulse()])
sim.run_for(1000)

[0.0]

Display output

freqz_fir(np.array(sim.results['0']) / 2)

<Figure size 640x480 with 2 Axes>

Create and display schedule

schedule = Schedule(sfg, cyclic=True)
schedule.show()