Patent ID: 6188288
Filing Date: 2001-02-13
Classification: H03L

Abstract:
A frequency synthesizer comprising:A) a variable frequency oscillator completely contained on a single integrated circuit;B) first digital counter receiving input from said variable frequency oscillator, comprising;i) a digital output that represents the number of cycles of said input since the beginning of the synthesis cycle, andii) means to change the modulus of the counter;C) a digital multiplier, receiving input from said first digital counter, comprising:i) a digital output that represents the product of the output of said counter and a multiplication factor, andii) means to change said multiplication factor of said multiplier;D) a reference oscillator;E) second digital counter receiving input from said reference oscillator;F) a digital adder comprising;i) means for receiving output from said digital multiplier;ii) means for receiving output from said second counter;iii) an output representing the difference between said digital multiplier output and said second counter output;H) a digital filter capable of receiving an output of said digital adder;I) a digital to analog converter which receives a digital output from said digital filter and provides an analog output; andJ) a low pass filter which receives the output from said digital to analog converter and drives said variable frequency oscillator.