Fully integrated ALL- CMOS AM transmitter with automatic antenna tuning
First Claim
Patent Images
1. A transmitter comprising:
- an oscillator forming part of a phase-lock loop (PLL), the oscillator in combination with the phase-lock loop generating a transmit frequency of the transmitter in response to a frequency reference, the oscillator including a resonant network;
a modulator, a portion of said oscillator and said modulator being formed on a single monolithic chip, wherein part of the resonant network is formed on the monolithic chip, the resonant network of the oscillator being completed by an antenna formed external to the single monolithic chip, a resonance frequency of said resonant network being automatically tuned by the phase-lock loop to the transmit frequency, and wherein the oscillator includes a differential structure of varactor diodes for tuning a resonance point of the antenna to the frequency of the oscillator; and
a varactor charge pump formed on the single monolithic chip to provide a bias charge for varactor diodes in the differential structure of varactor diodes.
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Abstract
A monolithic AM transmitter is disclosed. An external antenna forms part of a resonance network so that the antenna resonance point is automatically tuned to the transmit frequency. This provides flexibility with no added cost to the transmitter.
34 Citations
40 Claims
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1. A transmitter comprising:
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an oscillator forming part of a phase-lock loop (PLL), the oscillator in combination with the phase-lock loop generating a transmit frequency of the transmitter in response to a frequency reference, the oscillator including a resonant network;
a modulator, a portion of said oscillator and said modulator being formed on a single monolithic chip, wherein part of the resonant network is formed on the monolithic chip, the resonant network of the oscillator being completed by an antenna formed external to the single monolithic chip, a resonance frequency of said resonant network being automatically tuned by the phase-lock loop to the transmit frequency, and wherein the oscillator includes a differential structure of varactor diodes for tuning a resonance point of the antenna to the frequency of the oscillator; and
a varactor charge pump formed on the single monolithic chip to provide a bias charge for varactor diodes in the differential structure of varactor diodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A transmitter comprising:
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an oscillator forming part of a phase-lock loop (PLL), the oscillator in combination with the phase-lock loop generating a transmit frequency of the transmitter in response to a frequency reference, the oscillator including a resonant network;
a modulator, a portion of said oscillator and said modulator being formed on a single monolithic chip, wherein part of the resonant network is formed on the monolithic chip, the resonant network of the oscillator being completed by an antenna formed external to the single monolithic chip, a resonance frequency of said resonant network being automatically tuned by the phase-look loop to the transmit frequency, wherein the phase-lock-loop further includes a phase detector and a loop filter, the loop filter being coupled between the phase detector and the oscillator, the phase detector and the loop filter being formed on the single monolithic chip; and
a track and hold circuit coupled between the loop filter and the oscillator, the track and hold circuit being formed on the single monolithic chip, the track and hold circuit holding the phase-lock-loop state prior to disabling the oscillator in the event of a ‘
space’
transmission. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A transmitter comprising:
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an oscillator forming part of a phase-lock loop (PLL), the oscillator generating a transmit frequency of the transmitter based on a reference frequency;
a modulator, a portion of the oscillator and the modulator being formed on a single monolithic chip;
a resonant network connected to the oscillator, the resonant network including an antenna external to the monolithic chip and a controllable variable capacitance formed on the monolithic chip, a resonance frequency of said resonant network being tuned to the transmit frequency; and
a controller for receiving a first signal generated internal to the monolithic chip, the first signal being related to a detected phase in a transmit signal, and, in response, controlling the variable capacitance to vary the capacitance of the variable capacitance so that the resonance frequency of the resonant network is the frequency of the oscillator. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method of operating a transmitter comprising:
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generating a transmit frequency of the transmitter by an oscillator forming part of a phase-lock loop (PLL), an oscillator frequency being based on a reference frequency, the oscillator being formed on a monolithic chip;
modulating the oscillator frequency;
the transmitter including a resonant network connected to the oscillator, the resonant network including an antenna external to the monolithic chip and a controllable variable capacitance formed on the monolithic chip, a resonance frequency of said resonant network being tuned to the transmit frequency; and
receiving, by a controller, a first signal generated internal to the monolithic chip, the first signal being related to a detected phase in a transmit signal, the controller controlling the variable capacitance to vary the capacitance of the variable capacitance so that the resonance frequency of the resonant network is the frequency of the oscillator.
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Specification