Systems and methods for measuring the frequency of signals generated by high frequency medical devices

• US 9,529,025 B2
• Filed: 05/21/2013
• Issued: 12/27/2016
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Moul, Wayne L., Behnke, Robert J. II, Frushour, Scott E. M., Jensen, Jeffrey L.
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): NGUYEN, TRUNG Q
• Application Number:
  US13/898,632
• Publication Number:
  US 20140002056A1
• Time in Patent Office: 1,316 Days
• Field of Search: 324/76.11, 324 7639- 7654, 324/76.68, 324/85, 324/520, 324/633, 324/667, 324/674, 324/681, 324/727, 324/600
• US Class Current: 1/1
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00773 Sensed parameters
• CPC Class Codes: A61B 2018/00845 Frequency
• CPC Class Codes: A61B 2018/00869 Phase
• CPC Class Codes: A61B 2018/128 generating two or more frequencies
• CPC Class Codes: A61B 2018/1823 Generators therefor
• CPC Class Codes: G01R 23/00 Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
• CPC Class Codes: G01R 23/02 Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
• CPC Class Codes: G01R 23/145 by heterodyning or by beat-frequency comparison with the harmonic of an oscillator
• CPC Class Codes: G01R 25/00 Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
• CPC Class Codes: G01R 25/02 in circuits having distributed constants

Abstract

Systems and corresponding methods for determining characteristics of an output signal generated by a high-frequency medical device using low-frequency measurement systems are disclosed. A digital measurement system includes an oscillator, a mixer, and a controller coupled to each other. The oscillator provides a reference signal having a second frequency. The mixer generates a down-converted signal based on the output signal and the reference signal. The controller then determines a characteristic of the output signal (e.g., frequency or phase) based on the down-converted signal. An analog measurement system includes a filter having a center frequency, a rectifier, and a controller. The filter filters the output signal and the rectifier rectifies the filtered signal. The controller samples the rectified signal and determines a characteristic of the output signal based on the level of the rectified signal. The reference signal controller may adjust a characteristic of the output signal based on the determined frequency and/or phase of the output signal.

Claims

1. A system for measuring a characteristic of an output signal generated by a generator, the output signal having a first frequency, the system comprising:

an oscillator configured to provide a reference signal having a second frequency;

a first mixer configured to generate a first down-converted signal based on the output signal and the reference signal;

an amplifier configured to amplify the output signal;

a second mixer configured to generate a second, down-converted signal based on the amplified output signal and the reference signal; and

a controller configured to;

operate at a clock frequency lower than the first frequency;

determine a frequency of the output signal based on the first down-converted signal; and

determine a phase of the amplified output signal based on the second, down-converted signal.

2. The system according to claim 1, wherein the output signal is a digital signal or an analog signal.

3. The system according to claim 1, wherein the controller is further configured to control the output signal based on the determined frequency of the output signal.

4. The system according to claim 1, wherein the reference signal is a signal having a fixed or variable frequency.

5. The system according to claim 1, wherein the second frequency is set to a frequency such that the difference between the first and second frequencies is less than the clock frequency of the generator.

6. The system according to claim 1, wherein the second frequency is set equal to the first frequency.

7. The system according to claim 1, wherein the second frequency is set to a frequency offset from the first frequency.

8. The system according to claim 1, wherein the output signal is a DC value when the output signal and the reference signal are locked to the same frequency.

9. The system according to claim 1, further comprising one or more sensors coupled to an output of the amplifier, the one or more sensors configured to sense the amplified output signal and provide the sensed, amplified output signal to the second mixer.

10. A system for measuring a high frequency output signal generated by a generator, the system comprising:

a first filter having a first center frequency, the first filter configured to filter the output signal to obtain a first filtered signal;

a first rectifier configured to rectify the first filtered signal to obtain a first rectified signal;

an amplifier configured to amplify the output signal;

a second filter having a second center frequency, the second filter configured to filter the amplified signal to obtain a second filtered signal;

a second rectifier configured to rectify the second filtered signal to obtain a second rectified signal; and

a microprocessor configured to;

sample the first rectified signal;

determine a frequency of the output signal based on the level of the first rectified signal;

sample the second rectified signal; and

determine a phase of the amplified output signal based on a level of the second rectified signal.

11. The system according to claim 10, wherein the first filter is a notch filter or a band-pass filter.

12. The system according to claim 10, wherein the first filter is configured to attenuate the output signal as the frequency of the output signal moves away from the first center frequency.

13. A method for measuring a characteristic of a high frequency output signal generated by a generator, the output signal having a first frequency that is higher than a clock frequency of a processor of the generator, the method comprising:

generating a reference signal having a second frequency;

mixing the output signal and the reference signal to generate a first down-converted signal;

determining the characteristic of the output signal based on the first down-converted signal;

amplifying the output signal;

mixing the amplified output signal and the reference signal to obtain a second down-converted signal; and

determining a phase of the amplified output signal based on the second down-converted signal.

14. The method according to claim 13, wherein the characteristic is frequency or phase reference signal.

15. The method according to claim 14, further comprising verifying whether the characteristic of the output signal is within a predetermined range.

16. The method according to claim 14, further comprising adjusting the first frequency of the output signal to achieve a desired output impedance of the generator.