70.4.2.2. Common Mode and Differential Mode Components

Try these first

1. 1.

   What is a single-ended amplifier?

   Hint

   Think about the reference point it uses.

2. 2.

   Define common mode signal.

   Hint

   What does 'common' suggest about the signal?

3. 3.

   What term describes the portion of the signal that is common to both inputs?

   • Differential Mode
   • Common Mode
   • Single-Ended

   Hint

   The shared signal is not the differential aspect!

4. 4.

   True or False: A differential amplifier has one signal input.

   • True
   • False

   Hint

   Think about how many inputs are used!

5. 5.

   A differential amplifier receives two voltages, V1 = 5V and V2 = 3V. Calculate the output for a gain of 10.

   Hint

   Remember the formula for output voltage in terms of gain and input difference.

6. 6.

   Describe how a common mode rejection ratio (CMRR) can be derived from the gains of differential and common-mode signals.

   Hint

   Think about what kind of signals the amplifier boosts versus rejects!