A common mode differential amplifier is an electronic circuit that amplifies the difference between two input signals while rejecting any common mode signal that is present in both inputs. It is commonly used in applications where the desired signal is small compared to the common mode signal.
A common mode differential amplifier typically consists of two operational amplifiers (op-amps) connected in a differential configuration. The inputs are connected to the non-inverting and inverting inputs of the op-amps, while the outputs are connected to the differential output. The common mode signal is rejected due to the negative feedback between the two op-amps, while the difference between the two input signals is amplified and outputted.
One of the main advantages of a common mode differential amplifier is its ability to reject common mode signals, which can improve the signal-to-noise ratio and overall accuracy of the circuit. It is also a simple and cost-effective solution for amplifying small differential signals. Additionally, common mode differential amplifiers have a wide range of applications in fields such as telecommunications, instrumentation, and medical devices.
The gain of a common mode differential amplifier is calculated by dividing the output voltage by the input voltage difference. In an ideal differential amplifier, the gain is equal to the ratio of the resistors in the feedback network. However, in real-world circuits, factors such as op-amp imperfections and non-idealities in the resistors can affect the gain.
Common mode differential amplifiers are commonly used in instrumentation and measurement circuits to amplify small differential signals while rejecting any common mode noise. They are also used in audio and video equipment to remove common mode interference. Additionally, they are used in medical devices, such as electrocardiograms, to amplify and measure the small electrical signals produced by the body.