Technique for improving modulation performance of translational loop RF transmitters
First Claim
1. A method in a transceiver, comprising:
- comparing an analog signal that includes phase information and error pre-compensation information to a reference signal;
generating an oscillation based upon the comparison; and
down converting the oscillation to create the reference signal and producing the reference signal for the comparison step.
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Accused Products
Abstract
A transmit signal generated by the baseband processor in a translational loop type RF transmitter is “pre-distorted” so as to counter act magnitude distortion and group delay variation imposed by a narrow PLL signal filter. The pre-distortion occurs in two steps: a magnitude equalizer in the baseband processor pre-distorts the amplitude of the transmit signal according to the inverse of the PLL signal filter magnitude response, and a group delay equalizer linearizes the phase response of the entire transmitter chain, i.e., pre-distorts the transmit signal such that the combined phase response of magnitude equalizer, group delay equalizer, and PLL signal filter is linear. With such pre-distortion, a loop filter is provided for with component values that define a relatively small bandwidth for the loop filter to filter spurious tones that result from an IF reference feedthrough to a voltage controlled oscillator of the translational loop.
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Citations
20 Claims
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1. A method in a transceiver, comprising:
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comparing an analog signal that includes phase information and error pre-compensation information to a reference signal; generating an oscillation based upon the comparison; and down converting the oscillation to create the reference signal and producing the reference signal for the comparison step. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method in a transceiver, comprising:
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comparing an upconverted analog signal that includes phase information and error pre-compensation information to a reference signal produced by a reference signal generator; generating an oscillation based upon the comparison; down converting the oscillation to create an upconversion mixer signal; producing the upconversion mixer signal to a mixer; and mixing the upconversion mixer signal with an analog signal contain information and pre-compensation components to create the upconverted analog signal that includes phase information and error pre-compensation information. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method in a transceiver, comprising:
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digitally producing a magnitude response to counteract a down stream magnitude error; digitally producing a delay response to counteract a down stream delay error; producing a digital information signal based upon digital data; combining the digital information signal with the digital delay response and digital magnitude response having a phase value that corresponds to the digital data and the delay response to produce a pre-compensated digital data signal; producing an analog signal based upon the pre-compensated digital data signal; and generating an RF signal based upon the analog signal, which RF signal is characterized by a frequency that reflects a value of the digital data. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification