PRINTED CIRCUIT BOARD DESIGN OF A RF OSCILLATOR

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A high voltage RF oscillator circuit was previously constructed in the BU/NCRR mass spectrometry resource. This robust, tunable RF oscillator circuit could be used to cheaply drive multipole ion guides in FTICR. This project involved designing of a printed circuit board for the oscillator circuit in order to simplify construction and minimize debugging of these circuits. The circuit is laid out on a 2 layer PCB using the CAD tool, Layout Plus by Cadence Inc. The board outline is 5 by 4 (inches). The traces carrying high current dissipate a lot of heat (i2* R*t). These are made wider to prevent the melting of Cu tracks. Also, the nets which are at high potential (approx. 300 volts RF) can cause arcing or insulation breakdown between adjacent tracks. To prevent this, spacing between these H.V. traces is increased (approx. 200 mils for RF and 100 mils for DC). It has also been kept in mind to keep the RF components separate from the DC components in the layout of the circuit. A PCB has been developed, and tested, and several of them have been assembled. Currently, we are considering modifying the circuit to add a frequency stabilization and clamp circuit that were recently published as they appear that they will be useful in the future when we decide to adjust this oscillator for RF/DC operation. A paper was published in Reviews of Scientific Instrumentation regarding this work.