The basic principle of an operational amplifier analog circuit is as follows:
1. High Gain Amplifier
The operational amplifier is a high-gain differential amplifier. It can amplify the voltage difference between its two input terminals (inverting input and non-inverting input) by a very large factor. This high gain allows even small input signals to be significantly amplified. For example, an input voltage change of a few microvolts can result in an output voltage change of several volts.
The operational amplifier is a high-gain differential amplifier. It can amplify the voltage difference between its two input terminals (inverting input and non-inverting input) by a very large factor. This high gain allows even small input signals to be significantly amplified. For example, an input voltage change of a few microvolts can result in an output voltage change of several volts.
2. Differential Input
It has two input terminals. The output voltage is proportional to the difference between the voltages applied to these two inputs. This enables it to respond to the difference between two signals, which is useful in many applications where comparing or amplifying the difference between two voltages is required.
It has two input terminals. The output voltage is proportional to the difference between the voltages applied to these two inputs. This enables it to respond to the difference between two signals, which is useful in many applications where comparing or amplifying the difference between two voltages is required.
3. Virtual Short and Virtual Open
In most analyses, the following assumptions are made:
In most analyses, the following assumptions are made:
- Virtual short: Due to the extremely high open-loop gain of the operational amplifier, when negative feedback is applied, the voltages at the two input terminals are very close to each other. In an ideal case, they are considered equal, as if there is a short circuit between the two inputs. But in reality, there is no actual short circuit.
- Virtual open: The input impedance of an operational amplifier is very high. This means that the current flowing into the input terminals is extremely small and can be considered approximately zero, as if the input terminals are open circuits.
4. Feedback Network
An operational amplifier is often used in conjunction with a feedback network. The feedback network determines the overall function and characteristics of the circuit. By adjusting the components in the feedback network, different types of analog circuits can be created, such as amplifiers (inverting amplifiers, non-inverting amplifiers), filters, comparators, integrators, differentiators, etc. For example, in an inverting amplifier configuration, a resistor is used as the feedback element between the output and the inverting input. The gain of the amplifier is determined by the ratio of the feedback resistor to the input resistor.
An operational amplifier is often used in conjunction with a feedback network. The feedback network determines the overall function and characteristics of the circuit. By adjusting the components in the feedback network, different types of analog circuits can be created, such as amplifiers (inverting amplifiers, non-inverting amplifiers), filters, comparators, integrators, differentiators, etc. For example, in an inverting amplifier configuration, a resistor is used as the feedback element between the output and the inverting input. The gain of the amplifier is determined by the ratio of the feedback resistor to the input resistor.