def f2(Re1, Ic1, Vo1, Vcc, bjt):
Vbe1 = eee51.bjt_find_vbe(Ic1, Vcc - (Re1 * Ic1) - (Vcc/2), \
bjt['Is'], bjt['n'], bjt['VA'])
Re = (Vcc - (Vo1 + Vbe1)) / Ic1
return Re - Re1
ib2.append(float(line.split()[5]))
# convert to mV and mA
ic_mA = eee51.scale_vec(ic, g51.milli)
vbe_mV = eee51.scale_vec(vbe, g51.milli)
bjt_beta = [a / b for a, b in zip(ic2, ib2)]
# bjt parameters from our dc characterization
bjt_Is = 6.924988420125876e-13
bjt_n = 1.2610858394025979
g51.update_bjt_VA(-15.550605626760145)
g51.update_bjt_vce(specs['vce'])
# calculate the vbe needed for vce = 2.5V
reqd_vbe = eee51.bjt_find_vbe(specs['ic'], specs['vce'], \
bjt_Is, bjt_n, g51.bjt_VA)
# generate the ic for the ideal bjt model
# using our values for Is, n, and VA at vce = 2.5V
ic_ideal = [eee51.ideal_bjt_transfer(v, bjt_Is, bjt_n) for v in vbe]
ic_ideal_mA = eee51.scale_vec(ic_ideal, g51.milli)
# define the plot parameters
plt_cfg = {
'grid_linestyle': 'dotted',
'title': 'BJT 2N2222A Transfer Characteristics',
'xlabel': r'$V_{BE}$ [V]',
'ylabel': r'$I_C$ [mA]',
'legend_loc': 'upper left',
'add_legend': True,
# Let's calculate the resistor needed to set the
# output of the pnp current mirror to 1mA at a 2.5V output
specs = {'ic': 1e-3, 'vce': 2.5, 'vcc': 5.0}
#def fvbe(vbe):
# return vbe - eee51.bjt_find_vbe( \
# specs['ic'] * (1 + (vbe/abs(pnp_2n3906['VA']))) / \
# (1 + (specs['vce']/abs(pnp_2n3906['VA']))), \
# vbe, pnp_2n3906['Is'], \
# pnp_2n3906['n'], pnp_2n3906['VA'])
#
#vbe23 = optimize.fsolve(fvbe, 0.7)
vbe23 = eee51.bjt_find_vbe( \
specs['ic'], \
specs['vce'], pnp_2n3906['Is'], \
pnp_2n3906['n'], pnp_2n3906['VA'])
# since we want to vce2 = 2.5V, and vce3 = vbe3 = vbe2 approx 0.7, we can use
# VA to derate the ic of Q2:
# ic3 / ic2 = ( 1 + vce3/va ) / (1 + vce2/va)
ic3 = specs['ic'] * (1 + (vbe23/abs(pnp_2n3906['VA']))) / \
(1 + (specs['vce']/abs(pnp_2n3906['VA'])))
ib3 = ic3 / pnp_2n3906['beta_1mA']
ib2 = specs['ic'] / pnp_2n3906['beta_1mA']
iR = ic3 + ib3 + ib2
Rbias = (specs['vcc'] - vbe23) / iR
'swingpp': 3.0,
'vcc': 5.0
}
itail = 2 * specs['ic1']
vout = ((specs['vcc'] - specs['vomin']) / 2) + specs['vomin']
Rload = (specs['vcc'] - specs['vomin']) / itail
# common mode input range
cmir = vout - (specs['swingpp'] / 2) - 0.2 - specs['vxmin'] # vicmax - vicmin
vxbias = specs['vxmin'] + (cmir / 2)
# bias in the middle of the cmir
vbe34 = eee51.bjt_find_vbe( \
itail, \
vxbias, npn_2n3904['Is'], \
npn_2n3904['n'], npn_2n3904['VA'])
ib3 = itail / npn_2n3904['beta_1mA']
ic4 = itail
ib4 = ic4 / npn_2n3904['beta_1mA']
Re = [0, 50, 100]
Rm = [( specs['vcc'] - vbe34 - (R * ic4) ) / ( ic4 + ib3 + ib4) \
for R in Re]
vbe12 = eee51.bjt_find_vbe( \
specs['ic1'], \
vout - vxbias, npn_2n3904['Is'], \
npn_2n3904['n'], npn_2n3904['VA'])
'VA' : -6.567733723930889,
'beta_1mA' : 135.63663029082588
}
# Let's calculate the resistor needed to set the
# output of the pnp current mirror to 1mA
specs = {
'ic' : 1e-3,
'out' : 2.5,
'vcc' : 5.0
}
# calculate vbe5
vbe56 = eee51.bjt_find_vbe( \
specs['ic'], \
specs['out'], npn_2n3904['Is'], \
npn_2n3904['n'], npn_2n3904['VA'])
# get the loading of stage 2
ib5 = specs['ic'] / npn_2n3904['beta_1mA']
# calculate vbe1
vbe14 = eee51.bjt_find_vbe( \
specs['ic'], \
vbe56, npn_2n3904['Is'], \
npn_2n3904['n'], npn_2n3904['VA'])
# get the vec of q2
vce2 = specs['vcc'] - vbe14
# Q2 now has to provide the input current of the 2nd stage
def f1b(Vx, Ic1, Vo1, Vic, bjt):
Vbe1 = eee51.bjt_find_vbe(Ic1, Vo1 - Vx, \
bjt['Is'], bjt['n'], bjt['VA'])
Vxp = Vic - Vbe1
return Vxp - Vx
vce = Vbe + vbe5
vbe3 = bjt['n'] * g51.VT * np.log(Ic / \
(bjt['Is'] * ( 1 + (vce/abs(bjt['VA'])))))
return vbe3 - Vbe
Vcc = 5.0
Ic3 = 1e-3
f1_args = (pnp_2n3906, Ic3, Vcc)
Vbe3 = optimize.root(f1, 0.6, args=f1_args).x[0]
Ic5 = 2 * Ic3 / pnp_2n3906['beta_1mA']
Vce5 = Vcc - Vbe3
Vbe5 = eee51.bjt_find_vbe(Ic5, Vce5, \
pnp_2n3906['Is'], pnp_2n3906['n'], pnp_2n3906['VA'])
Vce3 = Vbe3 + Vbe5
Vo1 = Vcc - Vce3
Ic1 = 1e-3
Vic = 1.8
def f1b(Vx, Ic1, Vo1, Vic, bjt):
Vbe1 = eee51.bjt_find_vbe(Ic1, Vo1 - Vx, \
bjt['Is'], bjt['n'], bjt['VA'])
Vxp = Vic - Vbe1
return Vxp - Vx