phase locked loop

Discussion in 'Homework Help' started by lava_123, Jul 2, 2013.

  1. lava_123

    Thread Starter New Member

    Jun 15, 2013
    24
    0
    guys i really need some help analysing this question. i've attached a picture of the circuit. the circuit shows a 565 ic. the question is to find the tracking frequency range of the pll. but i'm having a tough time even understanding the circuit. i know that the 12k resistor is the external resistor Rt of the pll. 0.01uF is the timing capacitor of the pll. everything is well understood except for 0.001uF capacitor at the top. what is the role of that. i dont quite know how to start analysing the problem.

    the only thing i can think of doing is finding out the free running frequency of the pll which would be given by
    f0= 0.25/(Rt*Ct) where Rt is the external resistor and Ct is the timing capacitor

    and i also know the 10uF resistor at the top along with an internal resistor of 3.6k would make a low pass filter. but i dont know what that 0.001uF capacitor is doing. if anyone can understand the significance of that please tell me.

    thanks :)
     
  2. lava_123

    Thread Starter New Member

    Jun 15, 2013
    24
    0
    hey guys i got the answer... the 0.001 uF b/w pin 7 and 8
    doesnt have any significance in calculations. apparently its added to eliminate noise.
     
Loading...