Among these are a generator and a lamp as load (incandescent, CFL, or LED), an antenna feeding a receiver front end, a power amplifier driving an antenna via a transmission line, or even an audio amplifier powering loudspeakers. Q: What are some source/load pairings or transition locations?Ī: Almost any connection between function blocks or circuit elements can be considered a source/load pairing.
These reflections not only distort signals, but their returning energy can actually damage the source circuitry. Q: Why do we need to conjugate-match impedances?Ī: There are two related reasons: first, it can be proven analytically that doing so maximizes the transfer of power between the source and load, which is always a good thing second, it eliminates - or at least minimizes - reflections of signal energy from the load back to source due to impedance mismatch and “bumps” at impedance-transition points as shown in Figure 1. In a complex conjugate, the imaginary part has the opposite sign: R – jX ( Figure 1). Q: Remind me: what is “complex conjugate”?Ī: Every source or load has an impedance that can be expressed by a complex number, with a real (R) and imaginary (X) part: R + jX. In circuit designs spanning low-frequency audio through high-frequency RF, there’s considerable discussion about impedance matching between components or subcircuits, with various tools such as the Smith chart with is used to facilitate the matching.Ī: Impedance matching means that a signal source sees a load impedance which is the complex conjugate of its own impedance.
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