TABLE OF CONTENTS This section develops an improved insight into the RF signal processing of a splitter current and the associated mixed-mode s-parameter relationships. A transfer flow diagram is used to isolate and define the balance specification parameters of the splitter. The results will be expanded into the splitter CMRR and DMRR. This is demonstrated in Figures 5.12 and 5.13. These results will be summarized and applied to the combiner circuit.
The signal processing accuracy in RF circuits is dependent on the balance of the single-ended signals that are used to build a mixed-mode output. In communication receivers, direct conversion of RF signals to baseband frequencies is accomplished with balanced image-rejection-frequency converters (mixers). This frequency conversion requires a set of four single-ended signals called a balanced or differential-quadrature local oscillator signal set. A well-designed receiver rejects the image ( R i) [see (5.60)] and harmonic distortion signals. Among the many ways of generating this quadrature signal set from a single single-ended signal, is with a 90 splitter followed by a pair of 180 splitters. The accuracy of the phase and amplitude values of this quadrature signal-set circuit limits the direct-conversion-receiver-undesired-signal rejection. The splitter performance parameters associated with the single-ended output signal's accuracy are the phase balance and the amplitude balance. For a differential signal processing system, perfect balance results in zero cross-mode terms. For nonzero cross-mode terms, some of the differential signal power is converted to common-mode power, or the reverse process where some of the common-mode signal...
