Published:2011/9/14 10:09:00 Author:Joyce | Keyword: PLL , Composite Oscillator | From:SeekIC
This is a PLL composite oscillator composed of CD4046. It constitutes of reference oscillator, phase comparator, loop filter, voltage-controlled oscillator and programmable frequency divider etc. The reference oscillator can divide the frequency of the output of crystal oscillator module OSC which is 1MHZ or 100 kHz to get a signal of 1 kHz. Then the signal will be compared by CD4046 with the output of frequency dividing circuit N. There are two phase comparators: PC1 and PC2 within CD4046. PC1 is XOR logic, and the duty ratio of output of A and B must be 1:1.
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