TSP #23 - Tutorial on the Design and Characterization of Class-B and AB Amplifiers

In this episode Shahriar continues his investigation of discrete Bipolar amplifier design. The advantages and disadvantages of Class-A amplifiers are explained. The conceptual schematic of a Class-B amplifier is presented which leads to the introduction of Class-AB amplifier circuit to overcome the ’dead-zone’ impairment of a push-pull Class-B design. To further improve the Class-AB amplifier and lower its input impedance, a final Class-A followed by Class-AB amplifier is presented The component parameters are calculated and the schematics is explained in detail. All circuits are then implemented on a breadboard and tested both in the time domain and frequency domain. All schematics can be downloaded from The Signal Path website. Please note that in the schematic diagram the diode D1 is backwards! In the measured circuit the diode is placed correctly which is why the measurement results are correct. The Signal Path Blog