1. 7 pn Junction Diode: Small-signal Admittance

2. small signal voltage : Va
ac current : i
small signal admittance:
Y = G +jωC

3. 7.2 REVERSE-BIAS JUNCTION CAPACITANCE 7.2.1 General Information
C-V characteristics of pn diode

4. Junction or depletion layer capacitance
Charge density oscillation with a.c signal
(7.2)

5. 7.2.2 C-V Relationships (7.3) and (7.4) (7.5) Vbi→Vbi-VA
One sided power law profiles
(7.3)
and
(7.4)
(7.5)

7. Depletion region width for one sided power-law profiles
(7.6)
(7.7)
(7.8)
For varactor , tuning ratio

8. 7.2.3 Parameter Extraction/Profiling
Form C-V plot
Doping concentration versus position
(7.11)
(7.12)
(7.13)
Example 7.2

10. 7.2.4 Reverse-Bias Conductance
Differential dc conductance of a diode :
When the reverse bias exceed a few kT/q, G0→0
When the dc recombination-generation current dominates in the given diode,
(7.14)
(7.15)
(7.16)

11. 7.3 FORWARD-BIAS DIFFUSION ADMITTANCE 7.3.1 General Information
The admittance due to the minority carries charge oscillation