Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Phase shift by less than period of input
Reexamination Certificate
2000-01-28
2001-11-06
Cunningham, Terry D. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Phase shift by less than period of input
C327S236000, C327S238000, C327S254000
Reexamination Certificate
active
06313680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to phase splitters.
2. Description of Related Art
Phase splitters are required in a variety of applications. For example, in quadrature modulation, a phase splitter is used to split a local oscillator signal into sine and cosine components which are then mixed against in-phase and quadrature signal inputs to produce a single-side band output signal. With increasing demand for wireless services within limited bandwidths, higher performance phase splitters are required. Thus, new technology is needed to improve phase splitters.
SUMMARY OF THE INVENTION
This invention provides a phase splitter device that generates in-phase and quadrature outputs from an input signal. A first feedback loop of the phase splitter device ensures that a phase difference between the in-phase and quadrature outputs may be substantially a first set value (e.g., 90°). A second feedback loop of the phase splitter ensures that a difference between amplitudes of the in-phase and quadrature outputs may be substantially a second set value (e.g., zero).
The first feedback loop controls the phase difference between the phase of the inphase output and the phase of the quadrature output by generating a phase compare signal that is proportional to the phase difference. The phases of the in-phase and the quadrature outputs are adjusted until the phase difference is substantially equal to the first set value. The second feedback loop controls the amplitudes of the in-phase and quadrature outputs by generating an amplitude compare signal that is proportional to the difference between the amplitudes. The amplitudes are adjusted until the difference between the amplitudes is substantially equal to the second set value.
The in-phase output may be generated by a generator such as a high pass filter while the quadrature output may be generated by a generator such as a low pass filter, for example. Each of the generators may be controlled by a single control signal. The phase splitter device controls the amplitude difference and the phase difference between the in-phase and the quadrature outputs by a common mode of the control signals and a differential between the control signals, respectively. In this way, the phase splitter device generates in-phasing and quadrature outputs that have a phase difference and an amplitude difference that is substantially equal to the first and second set values (e.g., zero and 90°) using a single signal for the in-phase and quadrature output generators.
REFERENCES:
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patent: 5105168 (1992-04-01), DaSilva
patent: 5608796 (1997-03-01), Banu et al.
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patent: 6137999 (2000-10-01), Lovelace et al.
patent: 6157235 (2000-12-01), Bautista et al.
Havens Joseph Harold
McNeill Bruce Walter
Reid M. T. Homer
Agere Systems Guardian Corp.
Cunningham Terry D.
Oliff & Berridg,e PLC
Tra Quan
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