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##

## Delta-Sigma ADC

##

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# IMPORTS ===============================================================================

import numpy as np

import matplotlib.pyplot as plt

from scipy.signal import firwin

from pathsim import Simulation, Connection

from pathsim.blocks import (

Integrator, Adder, Scope, Source,

SampleHold, DAC, Comparator, FIR

)

from pathsim.solvers import RKBS32

# SYSTEM SETUP AND SIMULATION ===========================================================

v_ref = 1.0 #dac reference

f_clk = 100 #sampling frequency

T_clk = 1.0 / f_clk #sampling period

fir_coeffs = firwin(20, f_clk/50, fs=f_clk)

#blocks that define the system

src = Source(lambda t: np.sin(2*np.pi*t))

sub = Adder("+-")

itg = Integrator()

sah = SampleHold(T=T_clk, tau=T_clk*1e-3)

qtz = Comparator(span=[0, 1])

dac = DAC(n_bits=1, span=[-v_ref, v_ref], T=T_clk, tau=T_clk*2e-3)

lpf = FIR(coeffs=fir_coeffs, T=T_clk, tau=T_clk*2e-3)

sc1 = Scope(labels=["src", "qtz", "dac", "lpf"])

sc2 = Scope(labels=["itg", "sah"])

blocks = [src, sub, itg, sah, qtz, dac, lpf, sc1, sc2]

#connections between the blocks

connections = [

Connection(src, sub[0], sc1[0]),

Connection(dac, sub[1], lpf, sc1[2]),

Connection(sub, itg),

Connection(itg, sah, sc2[0]),

Connection(sah, qtz, sc2[1]),

Connection(qtz, dac[0], sc1[1]),

Connection(lpf, sc1[3]),

]

#simulation with adaptive solver

Sim = Simulation(

blocks,

connections,

dt_max=T_clk*0.1,

Solver=RKBS32

)

# Run Example ===========================================================================

if __name__ == "__main__":

Sim.run(2)

Sim.plot()

plt.show()