Digital Compensation for Distortion

Period of Performance: 04/09/2001 - 01/31/2002


Phase 1 SBIR

Recipient Firm

Linearizer Technology, Inc.
3 Nami Lane, Unit C-9
Hamilton, NJ 08619
Principal Investigator


The development of a digital signal synthesizer with integrated predistortion linearization (DSS/PDL) is proposed. The DSS/PDL will generate complex waveforms and predistort these waveforms so as to compensate for the distortion of high power amplifiers (HPAs). All signal generation and processing will be done digitally. The use of digital processing for the predistortion (PD) allows precise complex transfer characteristics to be more easily generated. It also allows greater flexibility in generating and modifying these responses. Linearizer Technology, Inc. (LTI) will use its extensive experience in the design and manufacture of linearizers to develop a new class of digital distortion equalizers that offer superior performance, are faster and more efficient than earlier designs, and that are commercially viable. A novel architecture will be employed to overcome stability problems and allow a wider dynamic bandwidth than previously possible. Linearizers are essential in systems carrying bandwidth efficient modulated (BEM), high data rate digital signals. The largest part of LTI's business is providing linearizers to manufacturers of HPAs for satellite earth stations. Linearization is also of great value to the wireless telephone and personal communication industry. The implementation of digital techniques will allow LTI to produce linearizers with greater performance at a lower cost.LTI specializes in the solution of problems involving all aspects of non-linearity in communications systems. Although LTI provides both manufacturing and consulting services, LTI's principal business is the production of linearizers for microwave power amplifiers. LTI now makes more than ten standard linearizer models covering the L,S,C,X,Ku,K and Ka bands, designed specifically for satellite ground station and terrestrial applications. In addition, LTI offers custom linearizer design services for frequencies from base-band through millimeter wave and above, and engineering consultation for all forms of distortion related problems. LTI Linearizers are in use in the US and throughout the world. Users include SSPA, TWTA and KPA manufacturers, satellite system operators, major teleports and satellite users. These customers have continually expressed a desire for linearizers that will provide increased linearity, greater operational bandwidth and do not require alignment. These are the features offered by the DSS/DPL to be developed by this proposal. The digital predistortion technology will be initially integrated into the design of our standard linearizer products and offered as an option. This option will be promoted in the same way other LTI products have successfully been promoted. A new line of high performance linearizers tailored to the cellular and personal communications market place will be developed. This market place has not been directly addressed by LTI because of the difficulties involved in producing linearizers with very high C/I performance. The development of multi-band linearizers will also be considered. Interest has been expressed in a single linearizer to cover the C,X and Ku-bands for tri-band TWTAs. Such multi-band performance has not been possible with a single PD generator, but with a digital PD it should be achievable. Other business opportunities are anticipated as word spreads of the capabilities of digital PD linearizers.