Pulse or digital communications – Transmitters – Amplitude modulation
Patent
1998-03-13
2000-06-20
Pham, Chi H.
Pulse or digital communications
Transmitters
Amplitude modulation
330285, 332106, 332159, H03C 152, H04L 2704
Patent
active
060786280
ABSTRACT:
A constant envelope modulator and transmit architecture for a wireless communication system is provided and a method for operating the same. The constant envelope modulator includes a differential encoder which receives data to be transmitted and creates in-phase and quadrature components of a modulation signal to be transmitted. The in-phase and quadrature components are passed through digital filters in order to give the modulation a particular shape. The in-phase and quadrature components of the modulation signal have both phase information and amplitude information on the modulation, where the constant envelope modulator removes the amplitude modulation (AM) information from the modulation signal to provide constant envelope in-phase and quadrature modulation signals and an accompanying AM envelope signal. The resultant constant envelope in-phase and quadrature modulation signals are combined at a radio frequency for transmission into a constant envelope phase modulation signal. The constant envelope phase modulation signal is fed through a non-linear power amplifier to bring the modulation signal to a proper output power level for transmission. The AM content of the modulation signal is then reintroduced into the constant envelope phase modulation signal at the non-linear power amplifier after the point of amplification of the constant envelope phase modulation signal in order to reintroduce the amplitude information into the signal. The constant envelope modulator and transmit architecture of the present invention allows the entire structure to be operated in an efficient, non-linear mode.
REFERENCES:
patent: 5579342 (1996-11-01), Crozier
patent: 5633893 (1997-05-01), Lampe et al.
patent: 5699383 (1997-12-01), Ichiyoshi
patent: 5793817 (1998-08-01), Wilson
patent: 5978421 (1999-11-01), Shoji
Clark Ricke W.
Griffith Scott
Conexant Systems Inc.
Pham Chi H.
Webster Bryan
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