Op-Amp Gain Calculator

Calculate the gain of operational amplifier circuits in different configurations (inverting, non-inverting, differential).

Calculate Your Op-Amp Gain Calculator

Op-Amp Configuration

R₁ (Ω)

R₂ (Ω)

Result

Gain = 11.0000

Non-inverting amplifier gain: 1 + (R₂/R₁)

What is an Op-Amp Gain Calculator?

An operational amplifier (op-amp) gain calculator helps determine the voltage amplification factor of various op-amp circuit configurations. It calculates how much the input signal is amplified by the op-amp circuit based on resistor values and circuit topology.

Common Op-Amp Configurations

Non-Inverting Amplifier

In a non-inverting amplifier, the input signal is applied to the positive input of the op-amp, and the output is in phase with the input (same polarity).

Gain Formula:

Gain = 1 + (R₂/R₁)

Inverting Amplifier

In an inverting amplifier, the input signal is applied to the negative input of the op-amp through a resistor, and the output is 180° out of phase with the input (opposite polarity).

Gain Formula:

Gain = -(R₂/R₁)

Differential Amplifier

A differential amplifier amplifies the difference between two input signals and rejects common-mode signals.

Gain Formula (when R₂/R₁ = R₄/R₃):

Gain = R₂/R₁

Gain Formula (when R₂/R₁ ≠ R₄/R₃):

Gain = (R₂/R₁) * (1 + R₄/R₃)

How to Use the Op-Amp Gain Calculator

Select the op-amp configuration (inverting, non-inverting, or differential).
Enter the resistor values (R₁, R₂, and for differential configurations, R₃ and R₄).
The calculator will automatically compute the gain based on the selected configuration and resistor values.

Practical Considerations

Higher gain values may lead to increased noise and reduced bandwidth.
Op-amps have limited gain-bandwidth product, meaning high gains are achievable only at lower frequencies.
Input impedance and output impedance vary between different configurations, affecting circuit performance.
Real-world op-amps have limitations like slew rate, offset voltage, and finite gain that may affect performance.

Applications of Op-Amp Circuits

Op-amp circuits are widely used in:

Audio amplifiers and pre-amplifiers
Signal conditioning for sensors
Active filters and oscillators
Instrumentation and measurement systems
Power supplies and voltage regulators
Analog computation and signal processing

Choosing Resistor Values

When selecting resistor values for op-amp circuits:

Consider standard resistor values (E12, E24, or E96 series).
Higher resistor values reduce power consumption but may introduce more noise.
Lower resistor values provide better noise performance but increase power consumption.
Typical values range from 1kΩ to 100kΩ for general-purpose applications.

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Frequently Asked Questions

An operational amplifier (op-amp) is a high-gain electronic voltage amplifier with differential inputs and a single output. It's designed to amplify the voltage difference between its two inputs and is widely used in signal processing, filtering, and instrumentation applications.

In an inverting amplifier, the output signal is inverted (180° phase shift) compared to the input signal, with gain = -R₂/R₁. In a non-inverting amplifier, the output signal maintains the same phase as the input signal, with gain = 1 + (R₂/R₁). The non-inverting configuration also has higher input impedance.

Several factors can cause actual gain to differ from calculated values: open-loop gain limitations of the op-amp, frequency response limitations (gain-bandwidth product), power supply limitations, component tolerances, parasitic capacitances, or if the op-amp is operating outside its linear region (saturation).

CMRR is a measure of an op-amp's ability to reject signals common to both inputs while amplifying the difference between them. It's expressed in decibels (dB) and is particularly important in differential amplifiers. Higher CMRR values indicate better performance in rejecting common-mode signals like noise.

When choosing resistor values: (1) Avoid very low values (<1kΩ) to prevent excessive current draw, (2) Avoid very high values (>1MΩ) to minimize noise and offset issues, (3) Consider the gain-bandwidth product of your op-amp, (4) Use standard resistor values for practical implementation, and (5) Match resistors in differential amplifiers to improve CMRR.

The gain-bandwidth product is a constant that describes the relationship between an op-amp's gain and its bandwidth. As gain increases, available bandwidth decreases proportionally. For example, an op-amp with a gain-bandwidth product of 10 MHz can provide a gain of 10 at 1 MHz, or a gain of 100 at 100 kHz. This limitation must be considered when designing high-gain or high-frequency circuits.

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