Lesson plan
Load pull
Load-pull is the colloquial term applied to the process of systematically varying the impedance presented to a device under test (DUT), most often a transistor, to assess its performance and the associated conditions to deliver that performance in a network. While load-pull itself implies impedance variation at the load port, impedance can also be varied at any of the ports of the DUT, most often at the source. Load-pull is required when superposition is no longer applicable, which occurs under large-signal operating conditions that make linear approximations unusable. The term load-pull derives from classical oscillator characterization whereupon variation of the load impedance pulls the oscillation center frequency away from nominal. Source-pull is also used for noise characterization, which, although linear, requires multiple impedances to be presented at the source to enable simultaneous solution of an over-determined system that yields the four noise parameters. Load-pull is the most common method globally for RF and MW power amplifier (PA) design, transistor characterization, semiconductor process development, and ruggedness analysis.…
Article summary
Load-pull is the colloquial term applied to the process of systematically varying the impedance presented to a device under test (DUT), most often a transistor, to assess its performance and the associated conditions to deliver that performance in a network. While load-pull itself implies impedance variation at the load port, impedance can also be varied at any of the ports of the DUT, most often at the source. Load-pull is required when superposition is no longer applicable, which occurs under large-signal operating conditions that make linear approximations unusable. The term load-pull derives from classical oscillator characterization whereupon variation of the load impedance pulls the oscillation center frequency away from nominal. Source-pull is also used for noise characterization, which, although linear, requires multiple impedances to be presented at the source to enable simultaneous solution of an over-determined system that yields the four noise parameters. Load-pull is the most common method globally for RF and MW power amplifier (PA) design, transistor characterization, semiconductor process development, and ruggedness analysis.…
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
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