RF-DAC based phase modulator
First Claim
1. A radio frequency (RF) phase modulator, comprising:
- a first RF digital-to-analog converter (RF-DAC) having a first pair of in-phase (I) and quadrature (Q) inputs configured to receive an I/Q digital baseband signal pair formatted according to a predetermined digital modulation scheme, a first plurality of local oscillator (LO) clock inputs configured to receive a first plurality of LO clock signals, and an RF output;
a second RF-DAC having a second pair of I and Q inputs configured to receive the I/Q digital baseband signal pair, a second plurality of LO clock inputs configured to receive a second plurality of LO clock signals of different phases relative to the first plurality of LO clock signals, and an RF output coupled to the RF output of the first RF-DAC; and
a third RF-DAC having a third pair of I and Q inputs configured to receive the I/Q digital baseband signal pair, a third plurality of LO clock inputs configured to receive a third plurality of LO clock signals of different phases relative to the second plurality of LO clock signals, and an RF output coupled to the RF outputs of the first and second RF-DACs.
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Accused Products
Abstract
A wideband, frequency agile, radio frequency digital-to-analog converter (RF-DAC) based phase modulator includes first, second, and third RF-DACs, each configured to upconvert an input I/Q digital baseband signal pair to a local oscillator (LO) frequency but with the first RF-DAC being driven by a first set of LO clocks, the second RF-DAC being driven by a second set of LO clocks that is forty-five degrees out of phase with respect to the first set of LO clocks, and the third RF-DAC being driven by a third set of LO clocks that is a further forty-five degrees out of phase with respect to the second set of LO clocks. First, second, and third upconverted analog signals produced by the first, second, and third RF-DACs are combined to reinforce the fundamental LO component while canceling 3rd-order and 5th-order LO harmonics.
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Citations
23 Claims
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1. A radio frequency (RF) phase modulator, comprising:
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a first RF digital-to-analog converter (RF-DAC) having a first pair of in-phase (I) and quadrature (Q) inputs configured to receive an I/Q digital baseband signal pair formatted according to a predetermined digital modulation scheme, a first plurality of local oscillator (LO) clock inputs configured to receive a first plurality of LO clock signals, and an RF output; a second RF-DAC having a second pair of I and Q inputs configured to receive the I/Q digital baseband signal pair, a second plurality of LO clock inputs configured to receive a second plurality of LO clock signals of different phases relative to the first plurality of LO clock signals, and an RF output coupled to the RF output of the first RF-DAC; and a third RF-DAC having a third pair of I and Q inputs configured to receive the I/Q digital baseband signal pair, a third plurality of LO clock inputs configured to receive a third plurality of LO clock signals of different phases relative to the second plurality of LO clock signals, and an RF output coupled to the RF outputs of the first and second RF-DACs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A harmonic rejection phase modulation method, comprising:
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receiving an input in-phase (I)/quadrature (Q) digital baseband signal pair formatted according to a predetermined digital modulation scheme; upconverting the input I/Q digital baseband signal pair to an LO frequency in accordance with a first set of LO clocks to produce a first upconverted I/Q digital signal; converting the first upconverted I/Q signal to a first upconverted analog signal; upconverting the input I/Q digital baseband signal pair to a LO frequency in accordance with a second set of LO clocks that is shifted in phase with respect to the first set of LO clocks to produce a second upconverted I/Q digital signal; converting the second upconverted I/Q signal to a second upconverted analog signal; upconverting the input I/Q digital baseband signal pair to a LO frequency in accordance with a third set of LO clocks that is shifted in phase with respect to the second set of LO clocks to produce a third upconverted I/Q digital signal; converting the third upconverted I/Q signal to a third upconverted analog signal; and combining the first, second, and third upconverted analog signals to produce a combined upconverted analog signal, said combining including constructively combining a fundamental LO component and destructively combining 3rd-order and 5th-order LO harmonics. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification