Patent ID: 7061991
Filing Date: 2006-06-13
Classification: H04L

Abstract:
1. A waveshaping circuit that shapes a first waveform to decrease a ratio of peak power to average power in the first waveform such that an available power of a radio frequency power amplifier can be efficiently used, where the shaping of the first waveform is substantially free from spectral pollution, the waveshaping circuit comprising: a preconditioning circuit adapted to receive an input symbol stream, the preconditioning circuit configured to compare data in the input symbol stream to a first reference and to modify the data in the input symbol stream by applying a first impulse to the input symbol stream selected to at least partially reduce the magnitude of a signal peak in the first waveform when the input symbol stream exceeds the first reference, the preconditioning circuit further configured to provide the modified symbol stream to a pulse-shaping filter, which maps the modified symbol stream to a baseband stream, where the pulse-shaping filter is configured to provide the baseband stream to a mixer, which upconverts the baseband stream by multiplication with an oscillator signal from a digital numerically controlled oscillator to an upconverted signal; a pulse generator adapted to receive the upconverted signal and to receive phase information from the digital numerically controlled oscillator, the pulse generator configured to generate a band-limited pulse when the pulse generator detects that the upconverted signal has a signal crest above a predetermined threshold, where the band-limited pulse is substantially limited to a frequency band allocated to the input symbol stream; a delay circuit configured to delay the upconverted signal to generate a delayed upconverted signal, where an amount of delay is approximately equal to a latency in the pulse generator; and a summing circuit adapted to sum the band-limited pulse from the pulse generator with the delayed upconverted signal from the delay circuit to generate the first waveform.