Virtual Labs

1. What is the primary role of the SPICE parameter

EG

(Energy Gap) in the diode model?

a: It determines the reverse breakdown voltage. Explanation

Explanation

b: It sets the value of the ideality factor

N

. Explanation

Explanation

c: It is used to calculate the temperature dependence of the saturation current

IS

. Explanation

Explanation

d: It models the series resistance

RS

. Explanation

Explanation

2. The thermal voltage

V_T

is defined as

kT/q

. At a standard room temperature of 300K, what is its approximate value?

a: 1.2 V Explanation

Explanation

b: 0.7 V Explanation

Explanation

c: 25.9 mV Explanation

Explanation

d: 1.0 mV Explanation

Explanation

3. Which SPICE parameters are specifically used to model the non-ideal recombination current that dominates at very low forward bias?

IS

and

N

Explanation

BV

and

IBV

Explanation

RS

and

IKF

Explanation

ISR

and

NR

Explanation

4. In the SPICE model, the ideality factor for the recombination current,

NR

, is typically fixed at what value?

a: 0.5 Explanation

Explanation

b: 1.0 Explanation

Explanation

c: 2.0 Explanation

Explanation

d: 3.0 Explanation

Explanation

5. A common graphical method to extract

RS

involves plotting

dV_D / d(ln(I_D))

versus

I_D

. What does the slope of this plot represent?

RS

Explanation

N \cdot V_T

Explanation

IS

Explanation

1 / RS

Explanation

6. If a diode's forward voltage

V_F

decreases significantly as temperature increases (at a constant

I_D

), this is primarily due to:

a: The increase in

RS

with temperature. Explanation

Explanation

b: The increase in

V_T

with temperature. Explanation

Explanation

c: The strong exponential increase of

IS

with temperature. Explanation

Explanation

d: The decrease in

N

with temperature. Explanation

Explanation

7. The SPICE parameter

XTI

(Saturation Current Temperature Exponent) is typically set to what value for a standard silicon pn-junction diode?

a: 1.0 (for mobility dependence) Explanation

Explanation

b: 1.5 (for Schottky diodes) Explanation

Explanation

c: 3.0 (for Si

n_i^2

dependence) Explanation

Explanation

d: -1.5 (for

RS

dependence) Explanation

Explanation

8. What is the main purpose of using numerical optimization (e.g., Levenberg-Marquardt algorithm) for SPICE parameter extraction?

a: To calculate

V_T

from first principles. Explanation

Explanation

b: To find a set of parameters that minimizes the error between the model equation and the measured data. Explanation

Explanation

c: To isolate and measure only the series resistance

RS

. Explanation

Explanation

d: To force the ideality factor

N

to be exactly 1. Explanation

Explanation

9. The total forward current in the SPICE model is the sum of the ideal diffusion current (using

IS, N

) and the non-ideal recombination current (using

ISR, NR

). At moderate to high currents, which component dominates?

a: The recombination current (

ISR

) Explanation

Explanation

b: The ideal diffusion current (

IS

) Explanation

Explanation

c: They are always equal. Explanation

Explanation

d: The current due to

RS

. Explanation

Explanation

10. In the high-level injection region, the slope of the

log(I_D)

vs.

V_D

plot corresponds to an ideality factor

N

approaching:

a: 0.5 Explanation

Explanation

b: 1.0 Explanation

Explanation

c: 2.0 Explanation

Explanation

d: Infinity Explanation

Explanation

Extraction of diode SPICE parameters related to forward Current-Voltage (I-V)