LC Tunable Oscillator

1
LC Tunable Oscillator
ELG4135 Electronics III Project

• Team Members
• Hubert Mamba
• Fu Jingyi
• Wang Jian

2
Introduction

• Tuned oscillators are largely used in data
  transmissions and radio communications.
• In RF circuits, mainly LC oscillators are used
  and their frequency is, most of the time,
  controlled using a variable-capacitance (varicap)
  diode . This method is a little bit complicated
  and costly .
• We present a single grounded resistance tunable
  sinusoidal oscillator that
• requires only three transistors, some passive
  components and no variable-capacitance and
• the oscillating frequency is controlled through a
  grounded resistor. Another grounded resistor
  independently controls the condition of
  oscillation.

3
Main Objective

• The main objective of this project is to
  investigate the performance of the new method
  (Single grounded resistance tunable Sinusoidal
  Oscillator).
• The usual method (VCO) requires the use of
  variable-capacitance diode to control the
  oscillating frequency value. This VCO is
  expensive and complicated to fabricate.

Differential VCO (Collpitt) Oscillator. (from
Lucio Carlo Rodoni http//n.ethz.ch/student/rodo
nil/da/bericht/node28.html
4
Main Objective (contd)

• The alternative (new)
• method requires no
• variable-capacitance, it
• is not expensive and is
• easy to implement. Its
• circuit diagram is shown
• in the figure bellow.