Method and apparatus for frequency synthesis in direct-conversion transmitters
First Claim
1. A transmitter circuit comprising:
- a first phase-locked loop configured to generate a first frequency signal that is non-harmonically related to a transmit frequency signal;
a first frequency divider configured to divide the first frequency signal to generate a mixing frequency signal for downconverting the transmit frequency signal into an intermediate frequency feedback signal;
a second frequency divider configured to generate an intermediate frequency reference signal by dividing the first frequency signal; and
a second phase-locked loop configured to generate the transmit frequency signal by phase-locking the intermediate frequency feedback signal to the intermediate frequency reference signal.
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Abstract
A method and apparatus for direct-conversion transmission generates a first frequency signal that is non-harmonically related to a transmit frequency signal, divides the first frequency signal to obtain a mixing frequency signal, divides the first frequency signal to obtain an intermediate frequency reference signal, generates the transmit frequency signal by using the mixing frequency signal to downconvert the transmit frequency signal into an intermediate frequency feedback signal, and phase-locks the intermediate frequency feedback signal to the intermediate frequency reference signal. The transmit frequency signal may be phase modulated, and may serve as an input to a saturated-mode power amplifier that can be configured for corresponding amplitude modulation. Alternatively, the un-modulated transmit frequency signal serves as the carrier signal input to a quadrature modulator, which imparts I/Q modulations to it, thereby producing a modulated carrier signal for input to a linear power amplifier.
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Citations
21 Claims
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1. A transmitter circuit comprising:
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a first phase-locked loop configured to generate a first frequency signal that is non-harmonically related to a transmit frequency signal; a first frequency divider configured to divide the first frequency signal to generate a mixing frequency signal for downconverting the transmit frequency signal into an intermediate frequency feedback signal; a second frequency divider configured to generate an intermediate frequency reference signal by dividing the first frequency signal; and a second phase-locked loop configured to generate the transmit frequency signal by phase-locking the intermediate frequency feedback signal to the intermediate frequency reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of direct-conversion transmission comprising:
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generating a first frequency signal that is non-harmonically related to a transmit frequency signal; dividing the first frequency signal to obtain a mixing frequency signal; dividing the first frequency signal to obtain an intermediate frequency reference signal; and generating the transmit frequency signal by using the mixing frequency signal to downconvert the transmit frequency signal into an intermediate frequency feedback signal and phase-locking the intermediate frequency feedback signal to the intermediate frequency reference signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A wireless communication device including a transmitter circuit that comprises:
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a first phase-locked loop configured to generate a first frequency signal that is non-harmonically related to a transmit frequency signal; a first frequency divider configured to divide the first frequency signal to generate a mixing frequency signal for downconverting the transmit frequency signal into an intermediate frequency feedback signal; a second frequency divider configured to generate an intermediate frequency reference signal by dividing the first frequency signal; and a second phase-locked loop configured to generate the transmit frequency signal by phase-locking the intermediate frequency feedback signal to the intermediate frequency reference signal.
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Specification