Patent ID: 7474709

Claim:
A frequency shift keying (FSK) modulator comprises: a phase-locked loop operably coupled to generate a first oscillation from a reference oscillation; a frequency divider module operably coupled to divide the first oscillation to produce a second oscillation; an image-rejection mixer operably coupled to mix the second oscillation with a low intermediate oscillation to produce a mixed data signal, wherein the image-rejection mixer includes: a first mixer operably coupled to mix the second oscillation with the low intermediate oscillation to produce a first mixed oscillation; a first phase-shift module operably coupled to phase-shift the second oscillation to produce a phase-shifted second oscillation; a second phase-shift module operably coupled to phase-shift the low intermediate frequency (IF) oscillation to produce a phase-shifted low IF oscillation; a second mixer operably coupled to mix the phase-shifted second oscillation with the phase-shifted low intermediate oscillation to produce a second mixed oscillation; and a mixer summing module operably coupled to sum the first mixed oscillation with the second mixed oscillation to produce the mixed data signal; and a summing module operably coupled to sum the mixed data signal with the first oscillation to produce an FSK modulated signal.