Practical takeaway
An op amp is a high-gain differential amplifier normally used with feedback so external components define a predictable circuit function.
E7G · Amateur Extra question group
Operational Amplifiers
An op amp is a high-gain differential amplifier normally used with feedback so external components define a predictable circuit function.
Amateur Extra exam focus
The explanation below teaches the ideas behind E7G while keeping the important terms recognizable. The Quiz Me button uses the current question-pool wording for this group.
1. Feedback sets closed-loop behavior
Negative feedback sacrifices some enormous open-loop gain to obtain stable, predictable gain, wider bandwidth, and lower distortion. Inverting and non-inverting configurations differ in phase and input impedance.
2. Real op amps have limits
Input common-mode range, output swing, slew rate, gain-bandwidth product, input bias current, noise, and supply voltage limit performance.
3. Op amps build more than amplifiers
With suitable components, op amps implement active filters, integrators, differentiators, comparators, oscillators, and instrumentation circuits. The feedback network determines the function.
E7G checklist
- Negative feedback defines stable closed-loop gain.
- Know inverting versus non-inverting behavior.
- Slew rate and gain-bandwidth product limit high-frequency/large-signal performance.
- External feedback networks let op amps implement filters and other analog functions.
Exam scope: NCVEC 2024-2028 Amateur Extra Class (Element 4), effective July 1, 2024 through June 30, 2028, with February 4, 2026 fourth errata. The current NCVEC pool is the exam authority; explanatory prose here is SPARKA teaching material. NCVEC pool