ECE 4330 Resistor and Capacitor Design

1
RESISTOR CAPACITOR

• Typical Bipolar Resistor Technology
• Sheet Resistance
• Serpentine Resistor Geometries
• MOS Capacitors

2
Bipolar Fabrication Masking Layers
3
Typical Bipolar Resistor Technology
P-Base Resistor Formation
Field Oxide
Field Oxide
P-base
N
P
P
N-Tub
P-Epi Layer
P
N
Top view of The resistor
4
Bipolar Resistor Electrical Equivalent
P
N
5
Sheet Resistance - Rs(?s)

• Rs is resistance of a square region of
  semiconductor with a given thickness - xj.

V -
L
L
I
xj
For uniformly doped material
Sheet Resistance
sq
6
Total Resistance Value
Resistance RS x (Number of Squares)
Resistance RS x Ld / Wd
7
Serpentine Resistor Geometries Used for high
value resistances
8
Comparison of the Chip Area required for
Serpentine Resistor Geometries Versus Multiple
Straight Resistors
9
Pinched Resistor Geometry
10
Parasitic Channel Formation Shunting Resistance
to Ground
11
MOS Capacitor Formation
12
MOS Capacitor Electrical Characteristics