Simple Method of Changing the Frequency Range of a Power Amplifier Circuit

Amplifier designers often face the challenge of modifying an existing circuit optimized for one frequency range to operate over a different and perhaps wider frequency range, which maybe higher or lower in frequency, using the same RF power transistor or transistors. This situation occurs when a manufacturer wants to reduce the number of designs required to cover its product portfolio or to create custom products to meet the needs of a specific application in a short time. When manufacturers meet market requirements with fewer designs, they can reduce cost, complexity, and time to market.

Given an unlimited amount of time and budget, the ideal approach would be to create an entirely new design, requiring extensive simulation and a new circuit board, assuming the new frequency range is within the capabilities of the transistor.

However, this being a less-than-ideal world, there is often neither the time nor budget available to take this approach. Fortunately, as this application note will show, if the design is single-ended and has no complicated matching sections, it is reasonably easy to extend or shift the bandwidth of the existing circuit design without resorting to extensive re-simulation, a new PCB, and many component changes.The approach reduces the time required for the transformation from weeks to as little as one day.