This document discusses the components used to generate accurate and variable frequencies for a local oscillator super heterodyne receiver and signal generator. A crystal oscillator provides a reference frequency which is then multiplied using a voltage controlled oscillator and divider to generate the output frequency. A phase detector compares the feedback and voltage controlled oscillator frequencies and a loop filter integrates any voltage difference to control the voltage controlled oscillator frequency.

2. Generate accurate and variable frequencies for :
 Local oscillator super heterodyne receiver
 Signal generator

3.  Crystal Oscillator – Provide reference frequency
 Voltage control oscillator (VCO) – Generate
frequency
 Divider – Control multiplication of generated
frequency from reference frequency
 Loop filter/LP filter – Integrate/Averageing
voltage from phase detector
 Phase Detector (PD)– Compare feedback
frequency and frequency generated by VCO.
Produce voltage if the these frequency differ.

4. Fvco= N Divider x Fref
*Most charge pump component build together with Phase detector in single
package
* P Counter = N Divider