Layout

1. Tutorial Questions
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2. Tutorial Questions
• Consider the triple cascode current
sink .assume all transistors operating in
saturation region with Id=10μA, Vds=50 V,
amplification factor gmr0=50. find the
value of output resistance. Neglect the
bulk effect.
• draw the circuit diagram of PMOS
cascode current mirror.
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7. Layout of simple current mirror
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8. Lateral diffusion
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9. Oxide encroachment
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19. MOS Wilson Current Source
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2
3
3 o
o
m
o r
r
g
R 
The drain current of Q2 to equal
the input current and the output
configuration assures that the
output current equals the drain
current of Q1.

20. Limitation of Wilson current mirror
• The principal limitation on the use of the Wilson
current mirror in MOS circuits is the high minimum
voltages between the ground connection.
• The input and output nodes that are required for
proper operation of all transistors in saturation.
• The voltage difference between the input node and
ground is vgs1+vgs4 .

21. MOS Widlar current source

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Standard Parameters for orbit 2μm technology
NMOS PMOS
Vt 0.83 volts 0.91 volts
K 50 μA/V2
17 μA/V2
λ 0.06 V-1
0.06 V-1
For analog design, minimum channel length (L) = 5 μm

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Solution :

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Design Example

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For PMOS, drain current in saturation region is
ID = (KP/2)W/L (VSG - Vtp)2
Substitute known values and calculate the value of Width of
PMOS transistor.
W = 70 μm

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solution