How does a non-inverting amplifier amplify an input signal with a gain greater than one?
1 Answer
A non-inverting amplifier is an electronic circuit that amplifies an input signal with a gain greater than one. It is a common configuration used in operational amplifier (op-amp) circuits. The non-inverting amplifier provides a stable and predictable gain, and it has a high input impedance, which means it doesn't load the input signal source significantly.
The basic schematic of a non-inverting amplifier consists of an op-amp with two external resistors: the feedback resistor (Rf) and the input resistor (Ri). Here's how it works:
Op-Amp Setup: The op-amp is connected with its inverting input (-) and non-inverting input (+) terminals. In a non-inverting amplifier configuration, the input signal is applied to the non-inverting input terminal.
Feedback Resistor (Rf): The feedback resistor (Rf) is connected between the output of the op-amp and the non-inverting input (+) terminal.
Input Resistor (Ri): The input resistor (Ri) is connected between the non-inverting input (+) terminal and the input signal source (Vin).
Virtual Ground Concept: In an ideal op-amp, the voltage at the inverting input (-) terminal is virtually at ground potential (0V). Therefore, the non-inverting input (+) terminal is also approximately at 0V.
Gain Calculation: The gain (Av) of the non-inverting amplifier is determined by the ratio of the feedback resistor (Rf) to the input resistor (Ri) and is given by the formula:
Av = 1 + (Rf / Ri)
Since Rf is greater than Ri (assuming a gain greater than one is desired), the gain (Av) will be greater than one.
Amplification: When an input signal (Vin) is applied to the non-inverting input (+) terminal, the op-amp amplifies this signal by the gain (Av) calculated above. The amplified output voltage (Vout) is then fed back to the non-inverting input through the feedback resistor (Rf), creating a closed-loop feedback system.
The closed-loop configuration ensures that the op-amp will adjust its output to maintain the virtual ground at the non-inverting input. This causes the amplified output to be stable and predictable, as long as the op-amp is within its linear operating range.
In summary, a non-inverting amplifier uses feedback to provide a gain greater than one for the input signal. By applying the concept of virtual ground, the circuit can maintain stability and accurately amplify the input signal.
The basic schematic of a non-inverting amplifier consists of an op-amp with two external resistors: the feedback resistor (Rf) and the input resistor (Ri). Here's how it works:
Op-Amp Setup: The op-amp is connected with its inverting input (-) and non-inverting input (+) terminals. In a non-inverting amplifier configuration, the input signal is applied to the non-inverting input terminal.
Feedback Resistor (Rf): The feedback resistor (Rf) is connected between the output of the op-amp and the non-inverting input (+) terminal.
Input Resistor (Ri): The input resistor (Ri) is connected between the non-inverting input (+) terminal and the input signal source (Vin).
Virtual Ground Concept: In an ideal op-amp, the voltage at the inverting input (-) terminal is virtually at ground potential (0V). Therefore, the non-inverting input (+) terminal is also approximately at 0V.
Gain Calculation: The gain (Av) of the non-inverting amplifier is determined by the ratio of the feedback resistor (Rf) to the input resistor (Ri) and is given by the formula:
Av = 1 + (Rf / Ri)
Since Rf is greater than Ri (assuming a gain greater than one is desired), the gain (Av) will be greater than one.
Amplification: When an input signal (Vin) is applied to the non-inverting input (+) terminal, the op-amp amplifies this signal by the gain (Av) calculated above. The amplified output voltage (Vout) is then fed back to the non-inverting input through the feedback resistor (Rf), creating a closed-loop feedback system.
The closed-loop configuration ensures that the op-amp will adjust its output to maintain the virtual ground at the non-inverting input. This causes the amplified output to be stable and predictable, as long as the op-amp is within its linear operating range.
In summary, a non-inverting amplifier uses feedback to provide a gain greater than one for the input signal. By applying the concept of virtual ground, the circuit can maintain stability and accurately amplify the input signal.