An Analog Modulator is Explained and the circuit operation is analyzed in this Video which is the 212th video in the Circuit Design Playlist. This Analog Modulator circuit implements Analog Multiplication of signals to achieve amplitude modulation (AM). The Circuit consists of three operational amplifiers, and three differential matched NPN BJT transistor pairs effectively forming a variant of the Gilbert Cell. This video discusses and answers the following topics: How does this example of Analog Modulator work? DC analysis, and how to quickly compute the AC small signal input-output Voltage Formula showing that output voltage signal is proportional to the product of the first input signal and the sum of the second and third input signal. All input voltages are considered as small signal. There are two symmetric positive and negative DC voltage supplies in this example. A combination of superposition, KVL, KCL and op amp virtual short are used to compute and show that Vout is proportional to V1*(V2+V3).
16 май 2024
