METHOD FOR GENERATING MULTI-PHASE OUTPUTS FROM A DDS
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2002-Jan-24
Direct Digital Synthesis (DDS) systems can be source systems are an image rejection mixer and a lii- expanded to provide integrated multiple signal sources ear power amplifier using a phase power combination. with independent phase offset relative to a given refer- The image rejection (IR) in the mixer example is deter- exe. Two application examples of multi-phase signal mined by the following relation: IR = -1Olog l+A'-2Acost3 1 +A2+2Acos8 -& Where: A = 10 0 = phase offset For a phase offset of 5' with &B = 0 the IR = A multi-phase signal source with integrated independ- -27.2dB, where the phase offset is a combination of all ent phase adjustment can reduce system cost, complex- the phase imbalance difference in the multiple signal ity, and size by achieving high performance phase com- source and the paths. A similar result occurs in a phase bination with path and component phase imbalance combinational linear power amplifier, where the phase compensation. offset becomes an error in the desired signal power level.