Chopper mixer telemetry circuit

Patent metadata

Field	Value
Publication number	US-9449501-B2
Application number	US-201414296206-A
Country	US
Kind code	B2
Filing date	Jun 4, 2014
Priority date	Apr 30, 2007
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

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.

First claim

The invention claimed is:

1. A wireless receiver comprising:
a first mixer amplifier that receives a telemetry signal modulated at a clock frequency, amplifies the telemetry signal 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 receives the same telemetry signal as the first mixer amplifier, 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; and
circuitry that produces a third output signal based on the first and second output signals.

2. The receiver of claim 1 , wherein the receiver resides within an implantable medical device.

3. The receiver of claim 2 , wherein the implantable medical device includes one of a cardiac pacemaker, a cardiac defibrillator, an electrical neurostimulator, and an implantable drug delivery device.

4. The receiver of claim 1 , wherein the first mixer amplifier includes a first integrator that integrates the first demodulated signal to extract the portion of the first demodulated signal to produce the first output signal, and wherein the second mixer amplifier includes a second integrator that integrates the second demodulated signal to extract the portion of the second demodulated signal to produce the second output signal.

5. The receiver of claim 1 , wherein the circuitry comprises quadrature reconstruction circuitry that combines the first and second output signals to produce the third output signal, the third output signal being an amplified representation of the telemetry signal.

6. The receiver of claim 5 , wherein the quadrature reconstruction circuitry comprises a first squaring unit that squares the first output signal, a second squaring unit that squares the second output signal, a summing unit that sums the squared first and second output signals, and a root unit that produces a square root of the sum as the third output signal.

7. The receiver of claim 6 , further comprising a decoder that decodes the third output signal.

8. The receiver of claim 1 , further comprising an antenna that receives the telemetry signal and presents the telemetry signal to the first and second mixer amplifiers.

9. A method comprising:
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 same modulated telemetry signal that was amplified to produce the first amplified signal to produce a second amplified signal;
demodulating the second 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; and
producing a third output signal based on the first and second output signals.

10. The method of claim 8 , further comprising receiving the wireless, modulated telemetry signal in an implantable medical device.

11. The method of claim 10 , wherein the implantable medical device includes one of a cardiac pacemaker, a cardiac defibrillator, an electrical neurostimulator, and an implantable drug delivery device.

12. The method of claim 8 , wherein extracting a portion of the first demodulated signal comprises integrating the first demodulated signal to produce the first output signal, and extracting a portion of the second demodulated signal comprises integrating the second demodulated signal to produce the second output signal.

13. The method of claim 8 , wherein producing the third output signal based on the first and second output signals comprises:
combining the first and second output signals to produce the third output signal.

14. The method of claim 13 , wherein combining the first and second output signals comprises squaring the first output signal, squaring the second output signal, summing the squared first and second output signals, and producing a square root of the sum as the third output signal.

15. The method of claim 14 , further comprising decoding the third output signal.

16. The method of claim 8 , further comprising receiving the telemetry signal via an antenna and presenting the telemetry signal to the first and second mixer amplifiers.

17. An apparatus comprising:
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 same modulated telemetry signal that was amplified to produce the first amplified signal to produce a second amplified signal;
means for demodulating the second 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; and
means for producing a third output signal based on the first and second output signals.

18. The apparatus of claim 17 , wherein the means for producing the third output signal comprises:
means for combining the first and second output signals to produce the third output signal.

19. The apparatus of claim 17 , further comprising means for delivering medical therapy.

20. The apparatus of claim 17 , further comprising means for sensing one or more physiological conditions.

21. An implantable medical device (IMD) comprising:
a first mixer amplifier that receives a telemetry signal modulated at a clock frequency, amplifies the telemetry signal 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 receives the same telemetry signal as the first mixer amplifier, 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; and
quadrature reconstruction circuitry that combines the first and second output signals to produce a third output signal, the third output signal being an amplified representation of the telemetry signal.

22. The IMD of claim 21 , further comprising:
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 am

Assignees

• Medtronic Inc
• Medtronics Inc

Inventors

• Grevious John J
• Denison Timothy J

Classifications

• A61N1/37252

  Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data · CPC title

• A61N1/37223

  Circuits for electromagnetic coupling · CPC title

• A61M5/172

  electrical or electronic {(A61M5/16804, A61M5/16831 take precedence)} · CPC title

• G08C17/02 Primary

  using a radio link · CPC title

• H03F3/393

  with field-effect devices · CPC title