Anaren Doherty combiners are designed for symmetrical two‐way Doherty power amplifier architectures that have even power slitting ratio between main and peak power amplifiers. A typical Doherty combining circuit consisting of two quarter‐wave‐length transmission lines of 50 Ohm and 35 Ohm are packaged in the combiner as shown in Figure 1.
A transmission line of fixed physical length is of quarter‐wave length only at a single frequency, this type of Doherty combiners are considered narrow band. Typically +/‐ 5% of bandwidth are achieved in this type of Doherty amplifiers. With several models, the Anaren Doherty combiner product line covers major communication bands ranging from 700 MHz to 2700 MHz. Each model is optimized for the center frequency of targeted frequency band. However, as new spectrum is being released worldwide to meet urgent capacity demands, the pre‐designed standard models can be tuned in customer applications to meet performance in these nearby frequency bands.
This document provides guidelines to tune these standard models for off‐band applications.