Interactive calculators with circuit diagrams — Voltage Follower · Comparator · Inverting · Non-Inverting · Differential · Summing
Voltage Follower (Unity Gain Buffer)
Gain = 1 · High Zin · Low Zout
Vout
—
Gain Av
1
Clamp High
—
Clamp Low
—
Vout = Vin
Output clamped to ≈ Vs − 1.5V (rail-to-rail) or Vs − 2V (standard)
Uses: impedance buffer, ADC driver, DAC output stage
Circuit Diagram
Output is directly connected to the inverting (−) input. The output copies Vin exactly, providing high input impedance and low output impedance — ideal for signal buffering.
Comparator (Open-Loop Op-Amp)
No feedback · Output = ±Vs · Digital output
Output State
—
Vout (approx)
—
Vdiff = V+−V−
—
If V+ > V−: Vout ≈ +Vs (HIGH) If V+ < V−: Vout ≈ −Vs (LOW)
Open-loop gain ≈ 100,000 → even µV difference → full rail swing
Circuit Diagram
No feedback path. Open-loop gain ~100,000 drives output to rail. V+ > V− → HIGH. V+ < V− → LOW. Use a dedicated comparator IC (LM393, LM311) for faster switching and open-collector output.
Inverting Amplifier
Av = −Rf / Ri · 180° phase shift
Gain Av
—
Vout
—
Input Impedance
—
Bandwidth (GBW=1MHz)
—
Av = −Rf / Ri | Vout = Av × Vin Zin = Ri (virtual ground at − input) BW = GBW / |Av| (GBW ≈ 1MHz for LM741/LM358)
Phase: 180° inverted · V+ tied to GND
Circuit Diagram
Vin connects through Ri to the virtual-ground (−) input. Rf provides negative feedback. V+ is grounded. Output is inverted: Vout = −(Rf/Ri) × Vin.
Vin connects directly to the non-inverting (+) input. R1 and R2 form a voltage divider feeding back to (−). Output is in-phase with input. Gain is always ≥ 1.
All inputs meet at the virtual-ground (−) node. Each contributes a current Vn/Rn. Rf converts the summed current to voltage. + input is grounded (R5 optional for bias cancellation).