Transcript Single-Ended Versus Differential Operation The transitions disturb the differential by equal amounts, leaving the difference in tact.

Single-Ended Versus Differential
Operation
The transitions disturb
the differential by
equal amounts, leaving
the difference in tact.
Immunity to Supply Noise
If VDD changes by
∆V, Vout changes by
the same amount.
Noise in VDD affects VX and VY,
but not Vx-Vy
Basic Differential Pair
CS with resistive source
degeneration
Interpretation: The resistance at the drain
Divided by the resistance in the source path
Treat M1 as a CS stage with
resistive source degeneration to
find VX/Vin
Half-Circuit Concept
Schematic of Differential
Amplifier
Simulation
Vin,m=1 mV
Vout,m=8.735 mV
Av=-8.735
Calculations:
Gm=1mS
ro=30.53 KOhm
RL=12 Kohm
Av=-Gm(ro||RL)=-8.615
Combine a Current Mirror with a
Differential Pair
Small Signal Gain
The swing at X is low since the impedance at X is 1/gm3.
So the X can be approximated as an AC ground for the
purpose calculating Gm.
Rout
When a voltage is applied to the output to measured Rout,
the gate voltage of M4 does not remain constant.
Active Current Mirror
Voltage Gain of Active Current
Mirror
Vin,pp=2 mV
Vout,pp=46.69 (Simulation)
Vout,pp=47.21 mV (Analytical calculation)