Virtual Labs

1. The total junction capacitance (

C_J

) in a diode is modeled as the sum of which two components?

a: Ohmic capacitance and Series capacitance Explanation

Explanation

b: Depletion capacitance and Diffusion capacitance Explanation

Explanation

c: Parasitic capacitance and Package capacitance Explanation

Explanation

d: Barrier capacitance and Transit capacitance Explanation

Explanation

2. Which SPICE parameter represents the junction capacitance at zero applied bias (

V_D = 0

M

(Grading Coefficient) Explanation

Explanation

TT

(Transit Time) Explanation

Explanation

CJO

(Zero-Bias Junction Capacitance) Explanation

Explanation

VJ

(Junction Potential) Explanation

Explanation

3. The SPICE parameter 'M' (Grading Coefficient) describes how the depletion capacitance varies with voltage. What is the typical value of 'M' for an abrupt (step) junction?

a: 0.33 Explanation

Explanation

b: 0.5 Explanation

Explanation

c: 1.0 Explanation

Explanation

d: 2.0 Explanation

Explanation

4. What does the SPICE parameter 'VJ' (also known as

PB

) represent in the C-V model?

a: The reverse breakdown voltage. Explanation

Explanation

b: The forward voltage drop at 1A. Explanation

Explanation

c: The built-in potential (contact potential) of the junction. Explanation

Explanation

d: The voltage at which

C_J = CJO

. Explanation

Explanation

5. For an ideal abrupt p-n junction under reverse bias, which plot is linear and commonly used to extract junction parameters?

C_J

vs.

V_R

Explanation

log(C_J)

vs.

V_R

Explanation

1/C_J^2

vs.

V_R

Explanation

1/C_J

vs.

V_R

Explanation

6. When plotting

1/C_J^2

vs.

V_R

for an abrupt junction, what does the voltage-axis (x-axis) intercept ideally represent?

a: The zero-bias capacitance,

CJO

. Explanation

Explanation

b: The built-in potential,

VJ

. Explanation

Explanation

c: The grading coefficient,

M

. Explanation

Explanation

d: The series resistance,

RS

. Explanation

Explanation

7. From the slope of the linear

1/C_J^2

vs.

V_R

plot, one can extract which physical parameter?

a: The transit time,

TT

. Explanation

Explanation

b: The doping concentration (e.g.,

N_A

N_D

). Explanation

Explanation

c: The saturation current,

IS

. Explanation

Explanation

d: The ideality factor,

N

. Explanation

Explanation

8. Which capacitance component dominates the diode's C-V behavior under strong *forward* bias?

a: Depletion capacitance (

C_D

) Explanation

Explanation

b: Diffusion capacitance (

C_{diff}

) Explanation

Explanation

c: Package capacitance Explanation

Explanation

d: Ohmic resistance capacitance Explanation

Explanation

9. The diffusion capacitance (

C_{diff}

) is primarily modeled in SPICE using the forward current (

I_D

) and which key parameter?

TT

(Transit Time) Explanation

Explanation

CJO

(Zero-Bias Capacitance) Explanation

Explanation

M

(Grading Coefficient) Explanation

Explanation

BV

(Breakdown Voltage) Explanation

Explanation

10. What is the purpose of the SPICE parameter 'FC' in the depletion capacitance model?

a: It models the frequency dependence of the capacitance. Explanation

Explanation

b: It sets the transit time for forward bias. Explanation

Explanation

c: It limits the depletion capacitance in forward bias to avoid singularities at

V_D = VJ

. Explanation

Explanation

d: It models the capacitance in reverse breakdown. Explanation

Explanation

Extraction of diode SPICE parameters related to Capacitance-Voltage (C-V)