Due Wednesday 2018-02-07 at the start of class.

This is a good time to catch up on your previous readings.

## 2. Lab 2 A - Bias Stability

Refer to the schematic parts (a) and (b) of Figure 1. Bias circuit schematics. Also read the section of the All About Circuits book directly linked in the References section of Lab 2A.

Your goal is to study the effect that variations of β have on the DC collector current.

• Read the [LEC] (aka the AAC online textbook) Chapter 4, section 4.10 to become familiar with the circuit analysis equations. The PDF version is better to reference since you can cite page numbers.

• Compute the collector currents for lab circuit (a) and (b) symbolically. Notice how Figure 4.88 can be used to analyze both circuits if each circuit’s base circuit is transformed using a Thevenin equivalent circuit like circuit (c).

• Compute the change in collector current for a change in β symbolically $\left(\dfrac{d}{d\, \beta} I_C\right)$.

Wanted: an expression that answers the question for each of circuits (a) and (b): If β changes by X%, what is the collector current’s change in percent?

→ find these numbers for β = ∞, 300, 100.

## 3. Lab 2 B - Small-Signal Amplifier

Treat the circuit of Lab 2 B as two amplifiers in cascade. From the DC bias conditions, compute the 3 main parameters of each sub-amplifier Rin, Rout, and voltage gain Av. Use the Guidebook tables to compute these numbers.

What is the predicted Rin, Rout, and voltage gain Av of the entire amplifier?