A non-inverting amplifier is a basic electronic circuit that amplifies an input signal with a positive gain, while maintaining the same polarity as the original signal. It is commonly used in analog electronics and signal processing applications to increase the amplitude of a signal without changing its waveform.
The basic configuration of a non-inverting amplifier consists of an operational amplifier (op-amp) and two resistors (R1 and R2). The op-amp is a high-gain differential amplifier with two inputs (inverting and non-inverting) and an output. The non-inverting input (+) and the inverting input (-) are the two terminals where the input signal and feedback signal are applied, respectively.
Here's a step-by-step explanation of the operation of a non-inverting amplifier:
Input Signal (Vin): The input signal (Vin) is applied to the non-inverting input (+) of the op-amp.
Feedback Network: A resistor (R2) is connected between the output of the op-amp and the inverting input (-). The other end of R2 is connected to the non-inverting input, forming a feedback network.
Virtual Ground: In the ideal op-amp model, the inverting and non-inverting inputs are assumed to have the same voltage level. Since the non-inverting input is connected to ground (0V) through R1, the inverting input also behaves like a virtual ground.
Amplification (Voltage Gain): Due to the virtual ground assumption and the nature of the op-amp, the voltage at the inverting input is forced to be equal to the voltage at the non-inverting input, which is the input signal (Vin). Therefore, the voltage across R2 is Vin (the voltage at the non-inverting input) minus the output voltage (Vout).
Op-Amp Behavior: The op-amp amplifies the voltage difference between the non-inverting and inverting inputs, attempting to make it zero. To do this, the op-amp's output will produce a voltage that is large enough to make the voltage across R2 almost equal to zero.
Output Voltage (Vout): Since the voltage across R2 is almost zero, the output voltage of the amplifier (Vout) can be calculated using the voltage divider formula:
Vout = Vin * (1 + R2/R1)
The gain of the non-inverting amplifier is given by (1 + R2/R1). If R2 is larger than R1, the gain will be greater than 1, resulting in signal amplification.
It's important to note that real-world op-amps have limitations and may not fully follow ideal behavior. Therefore, when designing and using non-inverting amplifiers, one should consider the op-amp's characteristics and limitations, and use appropriate components to ensure stable and accurate operation.