One of the last niche application areas in which bipolar devices were used was the 3-4 GHz microwave area, such as S-band radar. Main reason for this was that earlier generations of LDMOS showed a similar performance at 3 GHz compared to bipolar, which did not justify redesign of complex radar systems.
The main driver for LDMOS is a high volume application, which enables continuous improvement of the LDMOS technology [3,4], and this has resulted in the latest generation LDMOS, which outperforms bipolar at S-band frequencies with some additional advantages such as ruggedness and better thermal behaviour. In this article an overview is given of the LDMOS improvements at 3-4 GHz and the LDMOS performance for microwave products is presented.