Modulators – Phase shift keying modulator or quadrature amplitude modulator – Including discrete semiconductor device
Reexamination Certificate
2001-11-27
2003-07-01
Pascal, Robert (Department: 2817)
Modulators
Phase shift keying modulator or quadrature amplitude modulator
Including discrete semiconductor device
C332S109000
Reexamination Certificate
active
06587010
ABSTRACT:
FIELD OF THE INVENTION
In general, the present invention relates to the field of communication systems. More specifically, the present invention relates to the generation of modulated radio frequency (“RF”) signals from a linear mixing of signals.
BACKGROUND OF THE INVENTION
A direct-launch modulated signal source as known in the art includes a modulation signal source having a pair of digital-to-analog converter and low-pass filter combinations for providing both an in-phase baseband signal I and a quadrature baseband signal Q in analog form. The baseband signals I and Q are thereafter mixed with clock signals from a local oscillator, and then summed whereby the baseband signals I and Q are amplitude modulated and phase modulated. Since the baseband signals I and Q are in analog form, the mixers and a receiving power amplifier of the modulation signal source must be linear. This is a disadvantage of prior art direct-launch modulated signal sources, because linear power amplifiers are power inefficient.
A LINC modulated signal source as known in the art also includes a modulation signal source having a pair of digital-to-analog converter and low-pass filter combinations for providing the baseband signals I and Q in analog form. The prior art LINC modulated signal source provides the baseband signals I and Q to a pair of LINC synthesizers in order to generate two phase signals. A pair of phase modulators receive the phase signals, respectively, in order to generate two phase-modulated constant-envelope RF signals that must be amplified with high efficiency. The two RF signals are thereafter summed to obtain a desired amplitude modulated and phase modulated signal. The drawbacks of a prior art LINC modulated signal source is a complexity of the LINC synthesizers, a wide band requirement of the phase modulators, and a power efficient requirement of the signal combiner.
Thus, there is a need for a more efficient and less complex method to modulate a baseband signal containing amplitude- and/or phase-modulation to an RF frequency.
SUMMARY OF THE INVENTION
One form of the present invention is a modulated signal method. First, a baseband signal in digital form and a clock signal are received. Second, a pulse modulated signal in digital form is provided in response to a reception of the baseband signal and a reception of the clock signal, wherein the clock signal and the pulse modulated signal are synchronized.
A second form of the present invention is a modulated signal source comprising an oscillator and a pulse signal modulator. The oscillator is operable to provide a clock signal. The pulse signal modulator is operable to provide a pulse modulated signal in digital form in response to a reception of a baseband signal and the clock signal, wherein the clock signal and the pulse modulated signal are synchronized.
REFERENCES:
patent: 4084137 (1978-04-01), Welti
patent: 5838210 (1998-11-01), Midya et al.
patent: 5880644 (1999-03-01), Schmidt et al.
patent: 6246738 (2001-06-01), Acimovic et al.
“Integral Noise Shaping for Quantization of Pulse Width Modulation”: Pallab Midya & Matt Miller; Motorola Labs, Schaumburg, Illinois and Mark Sandler, Kings College, London. An audio engineering society preprint, presented at the 109thConvention Sep. 22-25, 2000 in Los Angeles, California, USA.
“Prediction Correction Algorith for Natural Pulse Width Modulation”: Pallab Midya, Bill Roeckner, Pat Rakers, & Poojan Wagh; Motorola Labs, Schaumburg, Illinois. An audio engineering society preprint, presented at the 109thConvention Sep. 22-25, 2000 in Los Angeles, California, USA.
Midya Pallab
Rakers Patrick
Wagh Poojan A.
Chang Joseph
Haas Kenneth A.
Motorola Inc.
Pascal Robert
LandOfFree
Modulated radio frequency signal generation method and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Modulated radio frequency signal generation method and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modulated radio frequency signal generation method and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3045759