Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-12-22
2001-06-19
Nguyen, Lee (Department: 2683)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S232100, C455S333000, C455S553100
Reexamination Certificate
active
06249686
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to radio frequency integrated circuits, and more particularly to a multi-mode RF integrated for use in a mobile radio or similar application.
There is a need for integrated circuits for applications such as mobile radio including but not limited to cellular telephones that can operate in more than one mode. For example, as the mobile radio and cellular telephone infrastructures move from predominantly analog to digital modes of operation, there is a need for mobile radios that operate in both of these modes, analog and digital. Dual mode portable telephones that operate in the cellular and PCS modes of operation allow a user to use the phone in the cellular band of frequencies or in the PCS band of frequencies depending on the user's location.
Dual mode operation also permits the radio frequency integrated circuits (RFICs) to be reconfigured, such as by inserting or removing amplifiers from the received signal path, so that weak signals can be amplified sufficiently by inserting the low noise amplifier in the path, or strong signals can be received without distortion by removing the low noise amplifier from the single path when the received signal strength is adequate for processing without it.
The need for additional functionality in RF integrated circuits, particularly the need for multiple mode RFICs conflicts with the demand for ever smaller systems. Mobile radios generally, and cellular telephones in particular are already very compact, and the demand for ever smaller phones continues to grow.
As phones become smaller, the physical requirements for smaller and smaller RFICs grows as well. One of the requirements for reducing the size of RFICs is to reduce the pin count. Adding additional features, such as multiple modes or functions as, heretofore, required that new control connections and additional pins be added to the IC to select among multiple modes or control the multiple functions. The addition of pins is inconsistent with the reduction in size of RFICs, and it is to this problem the present invention is addressed.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a radio frequency integrated circuit having multiple modes of operation and/or multiple functions.
It is another object of the invention to provide a multi mode or multi function RFIC having no additional control pins for selecting the mode or activating and deactivating the function.
It is another object of the invention to provide a multi mode or multi function RFIC that automatically determines the appropriate mode of operation and/or whether to activate or deactivate the function based on detecting signals within the RF integrated circuit, and using the state of those signals to control the mode or function of the RF integrated circuit without the need for the application of an external control signal and, more important, without the need for an extra pin through which the control signal is applied.
Briefly stated in accordance with a presently preferred embodiment of the invention, an RF integrated circuit for a cellular telephone set includes an improved control circuit for switching between at least two modes of operation, depending upon a characteristic of a signal received by the integrated circuit, the RF integrated circuit including a first input for receiving a first RF signal, when the integrated circuit is in a first mode; a second input for receiving a second input signal when the integrated circuit is in a second mode; and a detector on the integrated circuit couples to the first and second inputs for detecting the presence of the first and second RF signals, and producing an output signal at a logic port of the detector, depending on the state of the first and second RF signals; and a controller on the integrated circuit connected to the detector for switching the integrated circuit between the first mode and the second mode in response to the output signal without the need for the application of an external control signal to the integrated circuit.
In accordance with another aspect of the invention, the integrated circuit includes a first RF amplifier on the integrated circuit and operative in a first mode, the RF amplifier having a first control input for activating the amplifier, the integrated circuit also including a second RF amplifier on the integrated circuit operative in the second mode, and having a second control input for activating the second RF amplifier, the first and second control inputs connected to the controller, so that the first RF amplifier is activated in the first mode, and the second RF amplifier is activated in the second mode.
In accordance with yet another aspect of the invention, an RF processor integrated circuit is provided for a cellular telephone that can operate in a PCS mode and a cellular mode, and a controller for switching between modes without the application of an external control signal from a source off the chip.
In accordance with another aspect of the invention, an autonomous RF integrated circuit includes a controllable attenuator in a signal path of the integrated circuit, and a detector responsive to the received signal level for generating the signal output related to the received signal level, the attenuator having a control input connected to the detector for changing the attenuation of the attenuator in response to the strength of the received signal.
In accordance with another aspect of the invention, an autonomous RF processor integrated circuit includes a low noise amplifier and a detector responsive to the received signal level for selectively inserting the low noise amplifier in the signal path, or of removing it where the received signal strength is adequate for processing without the amplifier.
REFERENCES:
patent: 5004934 (1991-04-01), Furauta
patent: 5420911 (1995-05-01), Dahlin et al.
patent: 5519887 (1996-05-01), Lieu
patent: 5533099 (1996-07-01), Byrne
patent: 5694414 (1997-12-01), Smith
patent: 5694614 (1997-12-01), Bennett
patent: 5745523 (1998-04-01), Dent et al.
patent: 6134453 (2000-10-01), Sainton et al.
Dvorkin Vladimir
Wong Michael G.
Halajian Dicran
Nguyen Lee
Philips Electronics N.A. Corp.
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