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RF Oscillator

RF Oscillator

A High Voltage RF Oscillator for Driving Multipole Ion Guides

1. Abstract.

2. Advantages.

3. Circuit diagrams.

4. Citation.

5. Note: obsolete part substitute.


Abstract:

A high voltage RF oscillator circuit has been designed and constructed for driving multipole ion guides. The circuit is tunable from 500 kHz to 1.5 MHz by changing a capacitor and provides 0-1000 Vpp that is controlled by a 0-10 V input using a negative feedback circuit. This inexpensive circuit uses a set of high voltage transistors oscillating in tandem and does not require tuning of the resonance drive frequency as the oscillator automatically resonates at the (LC)-1/2 frequency. Matrix-Assisted Laser Desorption/Ionization – Fourier Transform Mass Spectrometry mass spectra were acquired using this tunable RF oscillator circuit to allow transmission of protein ions in the 8.5-39 kDa range through the quadrupole ion guide from the ion source to the mass analyzer.

Net advantages:

1. It’s self tuning. No need to tune to the resonance frequency.

2. Simple control: 0-10 V input = 0-1000 Vpp output.

3. Resonance frequency is controlled by changing a capacitor.

4. It’s cheap. Should cost <$200 in parts.


Circuit diagrams:


Citations:

O’Connor, P. B.; Earle, W. E.; Costello, C. A. A High Voltage RF Oscillator for Driving Multipole Ion Guides J. Am. Soc. Mass Spectom. 2002, 13, 1370-1375. Link

Mathur, R.; O’Connor, P. B. Design and implementation of a high power rf oscillator on a printed circuit board for multipole ion guides Rev. Sci. Instrum. 2006, 77, 114101 link

note: if you can’t download the paper, please email me and I will send you the pdf file.


Notes:

As is unfortunately very common in the electronics industry, the primary transistor oscillator that is used in this circuit, the Panasonic 2SC5392 has gone obsolete. A prospective substitute is BUH51 from ON Semiconductor, we have tested this replacement.

To download the PCB layout files with the bill of material for the RF oscillator click here.