Electronic component for microwave frequency systems with control circuit to adjust capacitance
| 486 - Abstract of the offer: |
| The European Space Agency (ESA) is interested in licensing an electronic component with a micro electro-mechanical (MEM) trimming capacitor with electrodes movable with respect to each other. A MEMS external device is measuring the capacitance between the electrodes, and the difference between measured and set capacitance is determined. This measurement output will cause injection of electric charges into the MEMS device (or a separate control electrode) which alters the electrostatic force moving one electrode with respect to the other and so adjusting the capacitance of the MEMS device to the desired value. |
Description of the offer:
This invention relates to electronic components with adjustable micro-electromechanical capacitors. Variable capacitors are required in a large variety of electronic circuits, in the frequency range from dc to microwave frequencies. Examples are Wheatstone bridges, voltage controlled oscillators (VCO), tuning capacitors in frequency variable filters, RF-matching circuits for easy tuning, controllable delay lines, phase shifters, impedance matching circuits and RF-power detectors.
At present time, electronically adjustable delay lines are based on the use of semiconductor diodes such as varactors, Schottky diodes or tunnel diodes. These diodes operate on a wide frequency band and offer short response times, making it attractive to fast variable signal levels and short pulses. However, these semiconductor diodes suffer also from a number of disadvantages limiting their usage. They are not capable of resisting high voltages or high powers, and their characteristics are highly temperature sensitive. Additionally they create excessive thermal noise (active device), and suffer from parasitic ohmic resistance lowering the achievable RF-circuit quality factor. In contradiction, Micro-ElectroMechanical (MEM) components are consisting of metal electrodes (in its simplest form there is just a fixed and a mobile electrode, moved by an electric field which generates an electrostatic force) can be used as switches or variable capacitors, avoiding a few disadvantages of a semiconductor diode. In particular, such a MEM component has a high Q- factor and generates low noise (passive element). It usually comprises a fixed electrode and a mobile electrode, the position of which is adjusted using an electrostatic force generated by an electric field applied to the mobile electrode.
Innovations and advantages:
- The electrostatic force is not generated by voltage but charge control (eg. applying a pulsed current source).
- This variable capacitor concept based on charge control is best suited for super-high bandwidth RF-power (radio frequency power) detector. Not only a dc-voltage (direct voltage) causes an electrostatic attractive force, but also any ac-voltage.
Domain of Application:
- Spectrometry (RAMAN, LIBS), Remote sensing, Earth Observation, Measurements in Chemistry, Geology, Environment, Security.
- Chromatographs and related laboratory equipment (including spectrometers).
