Operational Amplifier Fundamentals Unit 3 – The Noninverting Amplifier
Exercise 1 – Noninverting Amplifier DC Operation
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to operate a noninverting operational
amplifier using dc inputs. You will verify circuit operation with a multimeter.
EXERCISE DISCUSSION
- The noninverting amplifier is a closed-loop op amp configuration.
- Circuit gain (Av) is based on the ratio of R2 to R1: Av = 1 + (R2/R1).
- Due to the noninverting operation, the output and input voltages have the same polarity.
- R3 is adjusted to balance, or null, the circuit output (VO) to 0V. The circuit input must be
connected to circuit common. - A noninverting op amp amplifies an input voltage and does not invert the input voltage
polarity. - Since the circuit gain (Av) is 10, output voltage is +10 Vdc.
- For nonsaturated operation, the differential input voltage (VD) must be 0V.
- Since the op amp (+) input is at +1 Vdc, sufficient voltage is fed back (through R2) to
maintain VD at nearly 0V. - With respect to circuit common, both the (+) and (-) op amp inputs are at +1 Vdc.
- To determine circuit current distribution, apply Ohm's law.
- When the circuit input voltage (VI) is positive, electrons flow into the output terminal of the
op amp. - When VI is negative, electrons flow out of the output terminal of the op amp.