differential amplifier calculator

R1 (KΩ) 
R2 (KΩ)
RC(collector resistor)collector resistor (KΩ) 
RE(emitter resistor)emitter resistance (KΩ) 
vp (supply voltage) power supply voltage (V)
beta (dc current gain) dc current gain
VBE (base to emitter drop)base-emitter voltage drop (V)
Rs(source resistance): power supply internal resistance (Ω)
RL(load resistor)load resistor (Ω) 
fT(current gain bw product): current gain bandwidth (MHz)
CCB(cu collector-base cap.): capacitance between collector and base (pF)
CBE(Cπ, base-emitter cap.): capacitance between base and emitter (optional) (pF)

VC(collector voltage)collector voltage (V) 
VE(emitter voltage)emitter voltage (V) 
VB (base voltage)base voltage (V) 
IE(emitter voltage)emitter voltage (mA) 
IC(collector voltage)collector voltage (mA) 
IB (base voltage)base voltage (mA) 
gm (transconductance) transconductance
rπ (input resistance of bjt at low freq) transistor input resistance, low frequency (Ω)
re  (Ω)
RIN (Input Resistance of amp) amplifier input impedance (KΩ)
A (amplifier voltage gain) amplifier voltage gain
fP1 (MHz)
fP2 (MHz)

VB=  VP*R2/(R1+R2)

VE= VB-VBE

IE=VE/RE

Alpha= Beta/(Beta+1);

IC= Alpha*IE

VC= VP -  IC*RC/2

IB=IC/Beta

 

gm = Ic/25mA

re= Alpha/gm

rπ= Beta/gm

A=Alpha* rπ*RC/(Rs+2*rπ)/re

fP1=1/(2*π*(Rs||2*rπ)*(CBE/2+CBC))

fP2=1/(2*π*RC*CBC)

 

fT= gm/(2π*(CBE+CBC))

The lower pole is dominate: 

 

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