An electronically tuneable inductance with extended frequency range
The extension of the usable frequency range of an electronically tuneable inductance circuit is investigated. By means of numerical and analytical studies, the transistor-internal reverse transfer capacitance can be identified as a frequency-limiting element, which must be minimised. This is achieved by circuitry-wise compensation of the capacitive effect by introducing an additional inductance. The concept is verified through measurements of the practical implementation and shows an extension of the frequency range by two octaves throughout the VHF range, which proves beneficial for applications such as broadband matched and tuneable transmission lines, amplifier circuits, oscillators, or filters.
Experimental proof-of-principle of a passive, nearly reciprocal, transistor-based tuneable RF inductance
An innovative approach for tuneable reactances using the example of electronic inductances is introduced and the operation principle affirmed by measurement. Hitherto solutions for variable inductances often lack applicability in serial paths or do not exhibit passive behaviour. The presented circuit shows, even though transistor-based, a passive and reciprocal tuneable inductive behaviour at its terminals over a broad range of biasing conditions and frequencies. Thereby it accommodates more degrees-of-freedom in circuit design and possibilities for interesting applications, e.g., in integrated circuit design for a multitude of relevant applications in sensing and mobile communications. A test board was implemented and measured, confirming the principle-of-operation in agreement with numerical simulations, demonstrating a transistor-based, passive, tuneable, nearly reciprocal inductance over a frequency range larger than a decade.
Prediction of net pressure on pressure equalized cavities
Abstract A numerical model has been developed for prediction of net pressure on pressure equalized cavities. The results based on this model show good agreement with those obtained from mock-up tests. Parametric studies verify that reductions in cladding load are possible, with proper design of curtain walls.