Frequency synthesizer for integrated circuit radios
AssigneeBroadcom Corporation
InventorSeema B. Anand
Life of this patent
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Abstract
An integrated circuit radio transceiver and method therefor includes capacitive loop filter with selectable capacitive elements that are operable to adjust a signal level provided to a voltage controlled oscillator to control a frequency of an output signal of the oscillator. A plurality of switches are controlled by logic to define a discharge mode, a charge mode and charge sharing mode in which a plurality of capacitive elements share charge while generating the input voltage to the oscillator.
Claims26
An integrated circuit radio transceiver, comprising:
- a baseband processor for generating outgoing digital signals and for receiving and processing ingoing digital signals;
- front-end circuitry for producing outgoing RF based upon the outgoing digital signals and for producing the ingoing digital signals based upon received ingoing RF;
- and
- a two-stage loop filter within a frequency synthesizer of the front-end circuitry, the two-stage loop filter comprising:
- a signal level stage comprising first and second parallel coupled capacitive blocks;
- a selectable first switch operable to create a shorting signal path, the selectable first switch operably disposed across the first parallel coupled capacitive block and circuit common;
- a selectable second switch operably disposed between an input node of the selectable first switch and an input of the second parallel capacitive block;
- and
- logic operable to produce switch control signals to perform specified switching to open the selectable switch while closing the selectable switch to short the first parallel coupled capacitive block and to open the selectable switch while closing the second selectable switch to allow the first and second parallel coupled capacitive blocks to share charge.
A two-stage loop filter within a frequency synthesizer of front-end circuitry, the two-stage loop filter comprising:
- a signal level stage comprising first and second parallel coupled capacitive blocks;
- a selectable first switch operable to create a shorting signal path, the selectable first switch operably disposed across the first parallel coupled capacitive block and circuit common;
- a selectable second switch operably disposed between an input node of the selectable first switch and an input of the second parallel capacitive block;
- and
- logic operable to produce switch control signals to perform specified switching to open the selectable switch while closing the selectable switch to short the first parallel coupled capacitive block and to open the selectable switch while closing the second selectable switch to allow the first and second parallel coupled capacitive blocks to share charge.
A method for adjusting a frequency of oscillation in a frequency synthesizer of front-end circuitry of an integrated circuit radio transceiver wherein the frequency synthesizer comprises first and second parallel coupled capacitive blocks operably disposed to produce a signal to a voltage controlled oscillator, the method comprising:
- opening a connection between the first and second parallel coupled capacitive blocks and discharging the first parallel coupled capacitive block;
- charging the first parallel coupled capacitive block;
- closing the connection between the first and second parallel coupled capacitive blocks;
- equally distributing charge stored in the first and second parallel coupled capacitive blocks and producing a corresponding signal to the voltage controlled oscillator of the frequency synthesizer;
- and
- adjusting a capacitance of at least one of the first and second parallel coupled capacitive blocks to change a signal level of the corresponding signal produced to the voltage controlled oscillator.
Dependencies are inferred from the claim text.