Productive ToolboxOp-Amp Calculator
Calculate gain and output voltage for operational amplifier circuits including inverting, non-inverting, voltage follower, and summing amplifier configurations.
Op-Amp Calculator
Calculate gain and output voltage for operational amplifier circuits. Supports inverting, non-inverting, voltage follower, and summing amplifier configurations.
Actions
Circuit Configuration
Input Parameters
Common Examples
About Op-Amp Calculator
The Op-Amp Calculator is a fast, browser-based engineering utility that analyzes operational amplifier circuits including inverting amplifiers, non-inverting amplifiers, voltage followers (buffers), and summing amplifiers. This free online tool is essential for electronics students, electrical engineers, circuit designers, and hobbyists working with analog electronics.
By providing instant gain and output voltage calculations with step-by-step explanations, this calculator helps users quickly design and analyze op-amp circuits without manual calculation, reducing errors and saving time during circuit design and prototyping.
Op-Amp Circuit Configurations
Inverting Amplifier
Formula: Gain = -(R2/R1)
Phase: 180° inverted
Output signal is inverted relative to input. Gain determined by resistor ratio.
Non-Inverting Amplifier
Formula: Gain = 1 + (R2/R1)
Phase: Same as input
Output in phase with input. Gain always ≥ 1. Very high input impedance.
Voltage Follower
Formula: Vout = Vin
Gain: 1 (Unity)
Buffer with high input impedance and low output impedance. Ideal for isolation.
Summing Amplifier
Formula: Vout = -Rf × (V1/R1 + V2/R2 + V3/R3)
Use: Audio mixing, signal combining
Adds multiple input voltages with individual gain factors.
Real-World Examples
Example 1: Inverting Amplifier (Gain -10)
Input: Vin = 1V, R1 = 1kΩ, R2 = 10kΩ
Output: Gain = -10, Vout = -10V
Common audio amplifier configuration with 10x gain.
Example 2: Non-Inverting Amplifier (Gain 10)
Input: Vin = 2V, R1 = 1kΩ, R2 = 9kΩ
Output: Gain = 10, Vout = 20V
Sensor signal amplification with no phase inversion.
Example 3: Voltage Follower Buffer
Input: Vin = 5V
Output: Gain = 1, Vout = 5V
Impedance isolation between high-impedance source and load.
Example 4: Audio Mixer (2 Inputs)
Input: V1 = 1V, V2 = 1V, Rf = 10kΩ, R1 = R2 = 10kΩ
Output: Vout = -2V
Simple audio mixer combining two equal signals.
Common Applications
- ✓ Audio Amplification: Amplify microphone and line-level audio signals
- ✓ Signal Conditioning: Scale and buffer sensor outputs for ADC inputs
- ✓ Audio Mixing: Combine multiple audio sources with summing amplifiers
- ✓ Active Filters: Build low-pass, high-pass, and band-pass filters
- ✓ Instrumentation: Precision measurement and data acquisition systems
- ✓ Impedance Matching: Buffer high-impedance sources with voltage followers
- ✓ Analog Computation: Mathematical operations in analog circuits
Important Design Considerations
Resistor Values: Use values between 1kΩ and 1MΩ. Lower values (1kΩ-10kΩ) provide better noise performance but consume more power. Higher values (100kΩ-1MΩ) reduce power but may be affected by input bias currents.
Gain-Bandwidth Product: Op-amp frequency response is limited by GBW. Higher gain reduces maximum usable frequency. For example, with 1MHz GBW and gain of 100, maximum frequency is ~10kHz.
Slew Rate: Maximum rate of output voltage change. Insufficient slew rate causes distortion at high frequencies or large signal swings. Check datasheet specifications.
Power Supply Rails: Output voltage is limited by power supply voltages. Ensure adequate headroom (typically 1-2V from rails) for desired output swing.
Input Impedance: Inverting amplifiers have input impedance equal to R1. Non-inverting amplifiers have very high input impedance (typically GΩ range).
Benefits of Using This Calculator
- ✓ Instant Results: Calculate gain and output voltage immediately
- ✓ Multiple Configurations: Support for 4 common op-amp circuit types
- ✓ Step-by-Step Solutions: Understand the calculation process with detailed breakdowns
- ✓ Unit Conversion: Work with Ω, kΩ, or MΩ - automatic conversion handled
- ✓ Preset Examples: Quick access to common circuit configurations
- ✓ History Tracking: Save and recall previous calculations
- ✓ Export Reports: Generate detailed calculation reports for documentation
- ✓ Free & Browser-Based: No installation or registration required
Frequently Asked Questions
What is the difference between inverting and non-inverting amplifiers?
Inverting amplifiers produce an output that is 180° out of phase with the input (negative gain), while non-inverting amplifiers maintain the same phase (positive gain). Inverting amplifiers have input impedance equal to R1, while non-inverting amplifiers have very high input impedance.
When should I use a voltage follower?
Use a voltage follower when you need to buffer a high-impedance source (like a sensor) to drive a low-impedance load without loading the source. It provides impedance isolation with unity gain, making it ideal for interfacing between circuit stages.
How do I choose resistor values for op-amp circuits?
For most applications, use values between 10kΩ and 100kΩ. Lower values (1kΩ-10kΩ) provide better noise performance but consume more power. Higher values (100kΩ-1MΩ) reduce power consumption but may be affected by input bias currents and noise. Match resistor tolerances for precision applications.
What is gain-bandwidth product (GBW)?
GBW is a constant for a given op-amp that represents the frequency at which the open-loop gain drops to 1. It limits the maximum usable frequency for a given gain. For example, with 1MHz GBW and gain of 100, the maximum frequency is approximately 10kHz (1MHz ÷ 100).
Can I use any op-amp for any application?
No. Different op-amps have different specifications (GBW, slew rate, input offset voltage, noise, power consumption). Choose an op-amp based on your requirements: general-purpose (LM358, TL072), precision (OP07, OPA2277), high-speed (LM6171, AD8065), or low-power (LPV521, MCP6001).
How does a summing amplifier work?
A summing amplifier adds multiple input voltages with individual gain factors determined by the input resistors and feedback resistor. The output is the inverted weighted sum: Vout = -Rf × (V1/R1 + V2/R2 + V3/R3). It's commonly used in audio mixers and analog signal processing.
Related Electronics Topics
Amplifier Gain
Ratio of output to input signal amplitude in amplifier circuits
Feedback Networks
Resistor networks that determine op-amp gain and stability
Active Filters
Frequency-selective circuits using op-amps and passive components
Instrumentation Amplifiers
Precision differential amplifiers for sensor signal conditioning
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