Patent ID: 7015749
Filing Date: 2006-03-21
Classification: H03L,H04L

Abstract:
1. A frequency discriminator for detecting phase shifts between sequential pulses in a frequency-shift keyed (FSK) signal having a nominal frequency, said frequency discriminator comprising: a peak-to-peak detector capable of receiving said FSK signal and limiting an amplitude of said FSK signal to produce a limited FSK signal; a first current controlled delay line capable of receiving said limited FSK signal and delaying said limited FSK signal by a desired time delay to thereby produce a time-delayed limited FSK signal; a first multiplier capable of receiving and multiplying said limited FSK signal and said time-delayed limited FSK signal to thereby produce an output product signal proportional to a phase shift between said limited FSK signal and said time-delayed limited FSK signal; and a delay locked loop comprising a second current controlled delay line substantially similar to said first current controlled delay line, wherein said delay locked loop receives a reference clock signal having a time period equal to said desired time delay and adjusts a control current level in said second current controlled delay line until a delay of said second current controlled delay line matches said time period of said reference clock signal, wherein said control current level is then used to adjust a delay of said first current controlled delay line.