Basic Facts About Non-Inverting Amplifiers

Knowing to Basic Facts About Non-Inverting Amplifiers

Operational amplifiers are considered the building block of electronic circuitry, ranger from consumer electronics, computers, scientific equipments and industrial electronic devices. One of the many reasons why the op-amps are popular is because of the simplicity of its circuitry which can have many variations that may be used together with other electronic circuits.

Looking for Non-Inverting Amplifiers

For the operational amplifier, the second most basic type of amplifier circuit is the non-inverting amplifier (the first being the inverting amplifier). This type of amplifier circuit allows a signal input to flow through the positive (non-inverting) input of the amplifier while the negative (inverting input) of the amplifier is connected to two resistors, R1 and R2, where R1 is grounded and R2 connects to the output of the amplifier. The value of the two resistors will determine the voltage gain of the operational amplifier.

Leaning About Non-Inverting Amplifiers

In the non-inverting amplifier circuit, the amount of feedback voltage coming through the negative input is divided across the two resistors, thereby producing a negative feedback. This negative feedback will then be used to stabilize the voltage gain. This stabilization would mean that the amount of voltage entering the negative and positive inputs of the amplifier is the same.

Calculating the voltage gain of the non-inverting amplifier is easier to understand due to the fact that the input and output voltages has the same value, and since no current is being drawn from the amplifier's inputs, the current flowing to the resistors is the same.

With this facts in mind, the voltage gain can be determined using the formula Vin = Vout x R1/(R1 + R2). Simplifying the formula, it becomes  Av = 1 + R1/R2. This illustrates that the voltage gain may become high but never be lower than 1. If R1 becomes zero, voltage gain will be equal to 1; if R2 has a value of zero, then the voltage gain will reach infinity.


One thing to consider with non-inverting amplifiers is input impedance which can be considerably higher because the negative feedback maintains equal value in both inputs. A high input impedance may not be an issue (even ignored) by most amplifier circuit applications since those circuits contain additional resistors or other components that minimizes the effect, but if there are no such components, the high input impedance may generate noises in the output in the form of offsets or drifts.


Nowadays, using the non-inverting amplifier circuit is most commonly used than the inverting amplifier circuit. One type of usage for this circuit is the unity gain buffer, which maintains a value of 1 for the voltage gain. This type of buffer is commonly used to isolate different circuits or in separating active filters from each other.Non-Inverting Amplifiers