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Method and apparatus for filter selection from a frequency synthesizer data
| Details |
Inventors: Eswein, Glenn William; Curran, Daniel James; Hamilton, Graham Stuart; Reardon, James Francis; O'Connor, John Francis;
Assignee: Conexant Systems, Inc. (Newport Beach, CA)
Primary Examiner: Cumming; William
Assistant Examiner:
Attorney, Agent or Firm: Foley & Lardner
Modern portable communications units, and in particular cellular telephones, can contain several frequency bands for receiving and several frequency bands for transmitting signals. Typically these units contain a baseband unit and a frequency synthesizer unit, which may be embodied as VLSI integrated circuits. The baseband unit commonly contains the user interfaces and control signals for controlling other portions of the circuitry. The second unit is sometimes called a frequency synthesizer unit. The second unit is dedicated to producing frequencies that are used by the communications system to create RF signals for broadcast and also to take RF signals and extract the modulated signal from them for decoding. As personal communications units have begun using an increasing number of bands it is often necessary to configure different filters to receive or broadcast the different bands. Typically, the baseband Integrated Circuit or separate circuitry does this filter configuration management. The data for filter switching, however, can be decoded from the data that is communicated across the serial bus to the frequency synthesizer integrated circuit. By allowing the frequency synthesizer Integrated Circuit to control the filtering as well as the frequency synthesizer functions, integrated circuit pins can be eliminated from the baseband integrated circuit. In addition, timing and latency problems involved with commanding the frequency change over a serial bus and switching filters directly are eliminated. |
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In the following description of preferred embodiments, reference is made to the accompanying drawings, which form a part thereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced.
It should be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.
In addition, the present disclosure is illustrated by use of examples referenced to portable communication unit such as a portable phone.
It is to be understood that, although the present invention is useful in the portable telephone art, the present invention is applicable to a variety of systems that employ frequency synthesis and filtering mechanisms.
Illustrative embodiments presented are by way of example and are not to be construed as limiting the usefulness or applicability of the present invention.
To realize a cost-efficient design, portable telephone manufacturers may attempt to minimize size, weight, complexity, and power consumption.
Embodiments of the present invention therefore relate to portable communication transceivers in which bandpass filters may be switched using frequency synthesizer data.
It should be noted, however, that frequency synthesizers and filtering stages that accompany them, according to embodiments of the present invention, are not unique to portable communications.
Frequency synthesizers and filtering stages may be employed in a variety of electronics, including both wireless transmission systems as well as wired systems.
For purposes of simplifying the present disclosure, however, preferred embodiments of the present invention are described in relation to personal wireless communications systems, including, but not limited to digital mobile telephones, digital cordless telephones and the like.
Such personal communications systems typically include one or more portable receiver/transmitter units.
A generalized representation of a system environment, according to an embodiment of the present invention, is shown in FIG
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Cell Phones 
