Bandwidth extension of BJT amplifier using a novel three stage cascade topology

In the design of any amplifier, it is always required to give utmost attention to its frequency response analysis. While evaluating frequency response for some application it is also important to extend the bandwidth of an amplifier. Extending the bandwidth means increasing the upper 3 dB frequency and decreasing the lower 3 dB limit. Although there are different means by which this extension can be achieved, we have chosen the application of negative feedback for the purpose. We have derived some new topologies using three blocks representation from derived existing topologies, which fulfill our bandwidth requirements. We specially describe the use of cascading series-shunt, series-series and shunt-shunt type of feedback amplifiers as a composite block. In this paper, we are presenting a new approach based on the individual standard topologies and the two stage derived [3] topologies which extend the bandwidth of the amplifier around 26%.