113 lines
3 KiB
Python
113 lines
3 KiB
Python
#!/usr/bin/env python3
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import numpy as np
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from matplotlib import rcParams, pyplot as pp
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rcParams['figure.figsize'] = [10,7]
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default_window_position='+20+80'
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import sys
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sys.path.append("./pySmithPlot")
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import smithplot
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from smithplot import SmithAxes
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################################################################################
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# Operating Enviornment
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#####
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f0 = 28
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bw0 = 6.5 # assumed tuning range (GHz)
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bw_plt = 0.5 # Plotting range (GHz)
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fbw = bw0/f0 # fractional bandwidth
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frequency_sweep_steps = 101
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gamma_sweep_steps = 11
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gamma = 1 - np.power(f0 / (f0 + bw0/2),2)
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gamma_limit_ratio = 0.99 # how close gamma can get to theoretical extreme
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# Configuration Of Hardware
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#####
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q1_L = 10
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q1_C = 10
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l1 = 100e-3 # nH
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gm1 = 25e-3 # S
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# Compute frequency sweep
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#####
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w0 = f0*2*np.pi
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fbw_plt = bw_plt/f0
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delta = np.linspace(-fbw_plt/2,fbw_plt/2,frequency_sweep_steps)
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w = w0*(1+delta)
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f = f0*(1+delta)
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jw = 1j*w
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##################
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# Compute system
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#####
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c1 = 1/(w0*w0*l1)
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g1_L = 1 / (q1_L*w0*l1)
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g1_C = w0 * c1 / q1_C
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g1 = g1_L + g1_C
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# Verify gamma is valid
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#####
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gamma_max = g1 * np.sqrt(l1/c1)
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if gamma > (gamma_limit_ratio * gamma_max):
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print("==> WARN: Gamma to large, reset to %.3f (was %.3f) <==" % \
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(gamma_max_cap*gamma_max, gamma))
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gamma = gamma_max_cap*gamma_max
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gamma_swp = np.linspace(-gamma,gamma,gamma_sweep_steps);
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# compute correction factor for g1 that will produce common gain at f0
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g1_swp = np.sqrt( g1*g1 - (gamma_swp*gamma_swp) * c1/l1 )
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# and compute how much of a negative gm this requres, and it's relative
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# proportion to the gm of the assumed main amplifier gm.
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g1_boost = (g1_swp - g1)
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g1_ratio = -g1_boost / gm1
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c1_swp = c1 * (1 + gamma_swp)
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## Report System Descrption
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print(' L1 = %.3fpH, C1 = %.3ffF' % (1e3*l1, 1e6*c1))
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print(' Rp = %.3f Ohm' % (1/g1))
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print(' Max G1 boost %.2fmS (%.1f%% of gm1)' % \
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(1e3*np.max(np.abs(g1_boost)), 100*np.max(g1_ratio)))
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def db(volt_tf):
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return 20*np.log10(np.abs(volt_tf))
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def ang(volt_tf):
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return 180/np.pi*np.angle(volt_tf)
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#y_tank=np.zeros((len(delta),len(gamma_swp)))
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h1 = pp.figure()
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mgr = pp.get_current_fig_manager()
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ax1 = h.add_subplot(2,2,(1,3), projection='smith')
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ax3 = h.add_subplot(2,2,2)
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ax4 = h.add_subplot(2,2,4)
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for itune,gamma_tune in enumerate(gamma_swp):
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c1_tune = c1_swp[itune]
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g1_tune = g1_swp[itune]
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K = np.sqrt(c1/l1)/g1_tune
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y_tank = g1_tune + jw*c1_tune + 1/(jw * l1)
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#print(1/np.mean(np.abs(y_tank)))
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ax1.plot(y_tank, datatype=SmithAxes.Y_PARAMETER, marker="None")
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tf = gm1 / g1_tune * \
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1j*(1+delta) / \
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( 1j*(1+delta) + K*(1 - (1+gamma_tune)*np.power(1+delta,2)) )
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ax3.plot(f,db(tf))
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ax4.plot(f,ang(tf))
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################################################################################
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ax1.set_title('Tank Impedance')
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ax3.set_title('TF Gain')
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ax3.set_ylabel('Gain (dB)')
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ax4.set_title('TF Phase')
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ax3.set_ylabel('Phase (deg)')
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for ax_T in [ax3, ax4]:
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ax_T.grid()
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ax_T.set_xlabel('Freq (GHz)')
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ax_T.set_xlim(( np.min(f), np.max(f) ))
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h.tight_layout()
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mgr.window.geometry(default_window_position)
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h.show()
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