Phase splitter Concertina Phase Splitter

Differential Amplifier
This circuit allows to obtain an output signal
proportional to the difference of the input signals.
Where A d is the differential gain.
v out = A d (v in1-v in2)
On the other hand, there is an output signal also in
thecaseofV IN1 =V IN2, this signal depends from (not
desired) common mode amplification A C.Therefore
for a real differential amplifier, in general, we can write:
v out = A d (v in1-v in2) + A c (v in1+v in2)/2
vin1
RC
BJT1
REE
VCC
IC+ic1 IC+ic2
ic1d=-ic2d
-VEE
BJT2
RC
2IC+2ic1c
-V EE and R EE (R EE with high value) work as a current generator that:
determines the bias current I C of the two BJT and
contrasts the current variations of R EE.
The collector currents (i c1, i c2) related to v in1, v in2 consist of two components:
i = i + i ; i = i + i
C3
vin2
c1 c1d c1c c2 c2d c2c One relative to the difference of the signals the other relative to the common mode signal.
i = i ; i = - i
The current generator requires that |i c1d|>>|i c1c| and |i c2d|>>|i c2c|.
c2c c1c c1d c2d vout