Patent ID: 6671332
Filing Date: 2003-12-30
Classification: H04L

Abstract:
A circuit for providing phase shifted I and Q output signals from a received FSK modulated signal, comprising:means for receiving an FSK modulated signal; first, second and third mixers, coupled to receive the FSK modulated signal in phase from the receiving means; a local oscillator, generating an oscillator signal; phase shifting means coupled to the oscillator, for providing first, second and third versions of the oscillator signal, the second version of the oscillator signal being phase shifted from the first version of the oscillator signal, the third version of the oscillator signal likewise being phase shifted from the second version of the oscillator signal, the first second and third versions of the oscillator signal each being provided to one of the first, second and third mixers to produce first, second and third mixer output signals which are likewise phase shifted; a first summing circuit coupled to receive the first and second mixer output signals and providing an I output signal corresponding to the difference between the first and second mixer output signals; and a second summing circuit coupled to receive the second and third mixer output signals and providing a Q output signal corresponding to the difference between the second and third mixer output signals.