Radio frequency digital-to-analog converter (RFDAC) with dynamic impedance matching for high linearity
AssigneeQUALCOMM Incorporated
InventorsEdward Wai Yeung Liu, Vladimir Aparin
Life of this patent
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Abstract
Certain aspects of the present disclosure are directed to a radio frequency digital-to-analog converter (RFDAC). The RFDAC generally includes a plurality of digital-to-analog (DAC) unit cells. At least one DAC unit cell is capable of being configured in an active state or in a sleep state. For the at least one DAC unit cell, an output impedance of the DAC unit cell in the active state is equal to an output impedance of the DAC unit cell in the sleep state.
Claims30
A digital-to-analog converter (DAC) configured to output a radio frequency (RF) modulated signal, the DAC comprising a plurality of DAC unit cells, wherein, for at least one of the plurality of DAC unit cells:
- the DAC unit cell is capable of being configured in an active state or in a sleep state;
- an output impedance of the DAC unit cell in the active state is equal to an output impedance of the DAC unit cell in the sleep state;
- and
- the at least one of the plurality of DAC unit cells comprises:
- a capacitor;
- a first switch configured to selectively couple a terminal of the capacitor to a reference potential node;
- a second switch configured to selectively couple the terminal of the capacitor to a power supply rail;
- and
- a third switch configured to selectively couple the terminal of the capacitor to a common-mode voltage node.
A method for generating a radio frequency (RF) signal, the method comprising:
- receiving a digital signal;
- and
- converting the digital signal into the RF signal via a plurality of digital-to-analog (DAC) unit cells, comprising controlling at least one of the plurality of DAC unit cells, such that an output impedance of the at least one DAC unit cell when the DAC unit cell is in a sleep state is equivalent to an output impedance of the DAC unit cell when the DAC unit cell is in an active state, wherein:
- the output impedance of the at least one DAC unit cell when the DAC unit cell is in the sleep state is equal to an impedance of a passive network comprising one or more circuit elements;
- and
- during the sleep state, the passive network comprises:
- a capacitor;
- a switch with an on-resistance that matches the output impedance of the DAC unit cell in the active state;
- and
- a bias voltage source.
A wireless communication device comprising:
- a digital signal processor (DSP) configured to produce a digital signal;
- a digital-to-analog converter (DAC) configured to output a radio frequency (RF) modulated signal based on the digital signal from the DSP, the DAC comprising a plurality of DAC unit cells, wherein, for at least one of the plurality of DAC unit cells:
- the DAC unit cell is capable of being configured in an active state or in a sleep state;
- and
- an output impedance of the DAC unit cell in the active state is equal to an output impedance of the DAC unit cell in the sleep state;
- an antenna;
- and
- a transformer circuit having a first winding and a second winding, wherein the first winding is coupled to an output of each of the plurality of DAC unit cells and wherein the second winding is coupled to the antenna.
A digital-to-analog converter (DAC) configured to output a radio frequency (RF) modulated signal, the DAC comprising a plurality of DAC unit cells, the plurality of DAC unit cells comprising a capacitor array, wherein:
- for at least one of the plurality of DAC unit cells:
- the DAC unit cell is capable of being configured in an active state or in a sleep state;
- and
- an output impedance of the DAC unit cell in the active state is equal to an output impedance of the DAC unit cell in the sleep state;
- a first subset of the plurality of DAC unit cells is capable of being configured in the active state;
- a second subset of the plurality of DAC unit cells is capable of being configured in the sleep state;
- each of the DAC unit cells comprises a capacitor in the capacitor array;
- and
- for each of the first subset of the plurality of DAC unit cells in the active state, a terminal of the capacitor is selectively switched between a reference potential and a supply voltage at a carrier frequency of the RF modulated signal, based on a digital input to the DAC.
A digital-to-analog converter (DAC) configured to output a radio frequency (RF) modulated signal, the DAC comprising a plurality of DAC unit cells, wherein:
- the plurality of DAC unit cells comprises a capacitor array;
- for at least one of the plurality of DAC unit cells:
- the DAC unit cell is capable of being configured in an active state or in a sleep state;
- and
- an output impedance of the DAC unit cell in the active state is equal to an output impedance of the DAC unit cell in the sleep state;
- a first subset of the plurality of DAC unit cells is capable of being configured in the active state;
- a second subset of the plurality of DAC unit cells is capable of being configured in the sleep state;
- each of the DAC unit cells comprises a capacitor in the capacitor array;
- and
- for each DAC unit cell in the second subset of the plurality of DAC unit cells in the sleep state, a terminal of the capacitor is coupled to a common-mode voltage node.
Dependencies are inferred from the claim text.