The Load Modulated Balanced Amplifier as a Frequency Agile PA Technique

The introduction of the Load Modulated Balanced Amplifier (LMBA) by Prof Cripps in 2016 has opened a new direction of research that has led already to many different variants of the architecture, using the balanced core or even approaching the problem with circulators and transformers as the combining element. A big emphasis has been given to the efficiency enhancement capability of this architecture, with solutions like the inverted/sequential LMBA or the mixed Doherty/LMBA showing great performance. But the LMBA is not just a different way of implementing a Doherty response. The flexibility of the load modulation that was originally proposed also allows for frequency reconfiguration, and the first papers were focusing on this aspect, which can be improved by dedicated variants. This talk will explore in more detail such solutions as the Orthogonal LMBA and the Re-injection LMBA, and will discuss how to optimize their designs and which challenges are still present.