Load Matching Detector

For using continuous fractional voltage tracking (CFVT) it is crucial to know both, the optimal voltage fraction \(\varepsilon _\text {opt}\), and the actual transducer’s open-circuit voltage \(V_\text {g,oc}\). Therefore, this chapter presents a novel fully-analog load matching detector, which merges these two requirements: it is programmable for the needed \(\varepsilon _\text {opt}\), monitors a proportional measure to \(V_\text {g,oc}\left( t \right) \), and links both to a single output signal. This output signal indicates either the presence of an over-load or under-load condition. Thus, this detector can directly control a wide range of switch-mode converters. The review shows common methods to determine \(\varepsilon _\text {opt}\), and further related techniques for programming an input resistance of a SMPS for reasons of harvesting at the MPP. The details of the detection principle are explained, is followed by the circuit implementation with focus on low current consumption and wide voltage range operation. Simulation results of continuous tracking for both kinds of sources, AC and DC, show the efficient \(\,\mu \)W power operation.