Chopper mixer telemetry circuit
First Claim
1. A wireless receiver comprising:
- a first mixer amplifier that amplifies a telemetry signal modulated at a clock frequency to produce a first amplified signal, demodulates the first amplified signal at the clock frequency to produce a first demodulated signal, and extracts a portion of the first demodulated signal to produce a first output signal;
a second mixer amplifier that amplifies the telemetry signal to produce a second amplified signal, demodulates the second amplified signal at the clock frequency to produce a second demodulated signal that is approximately 90 degrees out of phase with the first demodulated signal, and extracts a portion of the second demodulated signal to produce a second output signal;
a first modulator that modulates an amplitude of the first output signal at the clock frequency;
a second modulator that modulates an amplitude of the second output signal at the clock frequency;
a first feedback path that applies the first modulated output signal as a first feedback signal to the first mixer amplifier;
a second feedback path that applies the second modulated output signal as a second feedback signal to the second mixer amplifier; and
circuitry that combines the first and second output signals to produce a third output signal.
1 Assignment
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Accused Products
Abstract
This disclosure describes a chopper mixer telemetry circuit for use in a wireless receiver. The receiver may be located in an implantable medical device (IMD) or external programmer. The chopper mixer telemetry circuit may include a mixer amplifier that operates as a synchronous demodulator to provide selective extraction of wireless signals received from a transmitter while suppressing out-of-band noise that can undermine the reliability of the telemetry link between an IMD or programmer and another device. The mixer amplifier may utilize parallel signal paths to convert the received telemetry signal into an in-phase (I) signal component and a quadrature (Q) signal component and recombine the I and Q signal components to reconstruct the total signal independently of the phase mismatch between the transmitter and receiver. Each signal path may include a chopper-stabilized mixer amplifier that amplifies telemetry signals within a desired band while suppressing out-of-band noise.
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Citations
24 Claims
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1. A wireless receiver comprising:
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a first mixer amplifier that amplifies a telemetry signal modulated at a clock frequency to produce a first amplified signal, demodulates the first amplified signal at the clock frequency to produce a first demodulated signal, and extracts a portion of the first demodulated signal to produce a first output signal; a second mixer amplifier that amplifies the telemetry signal to produce a second amplified signal, demodulates the second amplified signal at the clock frequency to produce a second demodulated signal that is approximately 90 degrees out of phase with the first demodulated signal, and extracts a portion of the second demodulated signal to produce a second output signal; a first modulator that modulates an amplitude of the first output signal at the clock frequency; a second modulator that modulates an amplitude of the second output signal at the clock frequency; a first feedback path that applies the first modulated output signal as a first feedback signal to the first mixer amplifier; a second feedback path that applies the second modulated output signal as a second feedback signal to the second mixer amplifier; and circuitry that combines the first and second output signals to produce a third output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising:
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receiving a wireless, modulated telemetry signal; amplifying the modulated telemetry signal to produce a first amplified signal; demodulating the first amplified signal at a clock frequency to produce a first demodulated signal; extracting a portion of the first demodulated signal to produce a first output signal; amplifying the modulated telemetry signal to produce a second amplified signal; demodulating the first amplified signal at the clock frequency to produce a second demodulated signal that is 90 degrees out of phase with the first demodulated signal; extracting a portion of the second demodulated signal to produce a second output signal; modulating an amplitude of the first output signal at the clock frequency to produce a first modulated output signal; modulating an amplitude of the second output signal at the clock frequency to produce a second modulated output signal; applying the first modulated output signal as a first feedback signal to a version of the modulated telemetry signal used to the produce the first amplified signal; applying the second modulated output signal as a second feedback signal to a version of the modulated telemetry signal used to produce the second amplified signal; and combining the first and second output signals to produce a third output signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An apparatus comprising:
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means for receiving a wireless, modulated telemetry signal; means for amplifying the modulated telemetry signal to produce a first amplified signal; means for demodulating the first amplified signal at a clock frequency to produce a first demodulated signal; means for extracting a portion of the first demodulated signal to produce a first output signal; means for amplifying the modulated telemetry signal to produce a second amplified signal; means for demodulating the first amplified signal at the clock frequency to produce a second demodulated signal that is 90 degrees out of phase with the first demodulated signal; means for extracting a portion of the second demodulated signal to produce a second output signal; means for modulating an amplitude of the first output signal at the clock frequency to produce a first modulated output signal; means for modulating an amplitude of the second output signal at the clock frequency to produce a second modulated output signal; means for applying the first modulated output signal as a first feedback signal to the modulated, differential telemetry signal; means for applying the second modulated output signal as a second feedback signal to the modulated, differential telemetry signal; and means for combining the first and second output signals to produce a third output signal. - View Dependent Claims (23, 24)
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Specification