Effect of delay mismatch on a feedforward amplifier

The suitability of feedforward amplifiers for satellite systems has thus far been limited by their poor overall DC to RF conversion efficiency. This is a consequence of the additional power amplifiers required to provide the distortion cancellation. In narrowband systems, other techniques have been used in preference to feedforward because they offer the advantages of improved efficiency, and reduced complexity. If, however, the power efficiency could be improved, and the size reduced, the benefits of feedforward could be more readily exploited. These improvements can be achieved by a reduction of the time delay elements. The paper presents an analysis and practical results of the implementation of shortened delay elements for both satellite (broadband) and narrowband applications