CMOS Design and Comparison of Instrumentation Amplifier using Traditional Method and GM/ ID Method using Cadence 180nm Technology

Instrumentation amplifiers are important integrated circuits when dealing with low voltage situations. This application note will teach the reader how to design an instrumentation amplifier by discussing important characteristics and by deriving a transfer function. An instrumentation amplifier is an integrated circuit (IC) that is used to amplify a signal. This type of amplifier is in the differential amplifier family because it amplifies the difference between two inputs. The importance of an instrumentation amplifier is that it can reduce unwanted noise that is picked up by the circuit. The ability to reject noise or unwanted signals common to all IC pins is called the common-mode rejection ratio (CMRR). Instrumentation amplifiers are very useful due to their high CMRR. Other characteristics, such as high open loop gain, low DC offset and low drift, make this IC very important in circuit design.