3G radio
AssigneeAnalog Devices, Inc.
InventorsSimon Atkinson, Palle Birk, Jonathan Richard Strange
Life of this patent
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Abstract
A dual mode transmitter for GSM and UMTS operation is provided. The GSM and UMTS paths share an oscillator and an intermediate frequency stage. Also, with the exceptio of the final stage of power amplification, the transmitter is provided as an integrated device.
Claims32
A transmitter for GSM and UMTS comprising
- an in-phase/quadrature up-converter for mixing in-phase and quadrature inputs with an intermediate frequency local oscillator signal;
- a GSM path including a phase locked loop;
- and
- a UMTS path;
- wherein
- a frequency generator is further provided to generate a first signal at a frequency F1, and
- the first signal is supplied as an input to an image reject mixer in the GSM path, to a mixer in the UMTS path, and as an input to divider which divides the first signal by three to create an intermediate frequency local oscillator signal which is supplied to the in-phase/quadrature up converter;
- and wherein the image reject mixer in the GSM path is controllable to select either an upper or lower side band such that the GSM path operates at either (1+⅓)F1 or (1−⅓)F1;
- and wherein the mixer in the UMTS path selects the upper side band so as to have a output at (1+⅓)F1.
A multi-mode transmitter operable for UMTS and GSM transmissions, comprising:
- a. a signal input for receiving a signal to be up converted on to a carrier signal by the transmitter;
- b. an oscillator for generating a first radio frequency signal having a frequency F1, where F1 is 1.5 or ¾ times a desired carrier frequency FC;
- c. a first divider for receiving the first radio frequency signal F1 and dividing it by three so as to form an intermediate frequency, IF, having a frequency substantially at 0.25 or 0.5 times the desired carrier frequency;
- d. at least one mixer for mixing the signal from the signal input with the intermediate frequency local oscillator signal to create a modulated intermediate frequency signal;
- e. a GSM path responsive to the modulated intermediate frequency signal;
- and
- f. a UMTS path responsive to the modulated intermediate frequency signal;
- wherein
- the GSM path comprises a voltage controlled oscillator within a phase locked loop, the phase locked loop including an image reject mixer receiving at a first input thereof the output of the voltage controlled oscillator, and at second inputs thereof the first radio frequency signal, such that it selectively outputs either the upper or lower side band of the mixing of the signals supplied to it as a signal in the phase locked loop;
- and
- wherein
- the UMTS path comprises at least one variable gain amplifier and a mixer for mixing the first radio frequency signal with the intermediate signal and outputting one of the side bands of the mixing process.
A transmitter for use in mobile telephony, the transmitter comprising a first transmitter portion for performing phase or frequency modulation, and a second portion of performing at least amplitude modulation, and wherein the first and second transmitter portions are provided with a first locally generated radio frequency signal from a shared oscillator such that the output frequency of the first and second portions is determined by the locally generated radio frequency signal.
Dependencies are inferred from the claim text.