Inital comit.

Basic transfer function and tank impedance plotting

tankPlot.py

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