5.7 Combiner General-Purpose Analysis/Specifications

Analysis of a combiner circuit begins like the prior analysis of a splitter circuit, with a general flow diagram (see Figure 5.16) that defines the specification parameters using mixed-mode s-parameters. The combiner takes inputs at two ports and combines them at an arbitrary phase at an output port. This combiner general flow diagram has an arbitrary phase transfer value of 180 , 90 , or 0 between the two combiner input ports. The combiner performance parameter of interest is a composite measure of the phase and amplitude imbalance between the mixed-mode input signals and the single-ended output signal, b _o. A 180 combiner outputs the difference of the two single-ended input signals, a ₁ and a ₂, while a 0 combiner sums the two single-ended input signals. The differential-mode input wave is defined as the difference of the two single-ended input signals.

(5.46)

Figure 5.16: Combiner signal-ended power signal transfer-flow diagram.

The common-mode input wave is defined as the sum of the two single-ended input signals,

(5.47)

The single-ended input signals, a ₁ and a ₂, are solved in terms of the mixed-mode input waves,

(5.48)

and

(5.49)

A combiner power-signal flow diagram is shown in Figure 5.16; the diagram omits input-to-input signal path and output mismatch. These simplifications assume single-ended s-parameter terms, S ₁₂, S ₂₁, and S ₃₃, or mixed-mode s-parameter terms, S _{dc 11}, S _{cd 11}, and S _{ss 22} are not considered...