PLL as Frequency Multiplier

Experiment 8

Aim:

To construct the circuit of PLL as frequency multiplier using IC 567.

Apparatus Required:

Theory:

Here the frequency divider is inserted between the VCO and the phase comparator. Since the output of driver is lock to the input frequency fin, the VCO is actually running at a multiple of the input frequency. The desired amount of multiplication can be obtained by selecting a proper divide by N network. For example to obtain the output frequency f out = 5 fin a divide by 5 network is needed. A small capacitor typically 1000pf is connected between pins 7&8 to eliminate possible oscillations.

Circuit Diagram

Internal Block Diagram of IC-567

Observations

Procedure

1. Connections are made as per the circuit diagram.

2. Supply is given and the input is given through audio oscillator. Multiplied output frequency is measured

Link to experiment

Go here and select Experiment 8

Demonstration Video