Electron paramagnetic resonance (EPR) systems with active cancellation

Patent metadata

Field	Value
Publication number	US-10663541-B2
Application number	US-201615574302-A
Country	US
Kind code	B2
Filing date	May 18, 2016
Priority date	May 18, 2015
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

An active cancellation system may be utilized to cancel interference, such as from transmitter leakage or self-interference in a transceiver of an electron paramagnetic resonance (EPR) spectrometer. The active cancellation system may be inserted between the transmitter and receiver. The active cancellation system may receive the output of the transmitter, and generate a cancellation signal with the same amplitude, but phase shifted relative to the self-interference signal. The cancellation system may include an attenuator/amplitude tuner, buffer, VQ generator, and phase shifter.

First claim

What is claimed is:

1. An active cancellation system comprising:
an attenuator/amplitude tuner receiving an output signal of a transmitter, wherein the attenuator/amplitude tuner provides attenuation and amplitude tuning of the output signal to produce a signal for cancellation of a TX self-interference signal;
a buffer receiving the signal from the attenuator/amplitude tuner, wherein the buffer provides additional amplitude tuning; and
a phase shifter receiving a buffer output signal from the buffer, wherein the buffer output signal is phase shifted to 180° relative to the TX self-interference signal to form a cancellation signal that is outputted to a receiver, wherein the cancellation signal is injected after a low-noise amplifier (LNA) of the receiver to minimize a noise figure (NF) degradation of the receiver due to active cancellation circuitry.

2. The system of claim 1 , where the buffer output signal is a differential signal, and the active cancellation system further comprises an I/Q generator receiving the differential signal from the buffer, wherein the I/Q generator converts the differential signal into a quadrature signal; and
wherein further the phase shifter receives the quadrature signal from the I/Q generator, and the quadrature signal is phase shifted to produce the cancellation signal.

3. The system of claim 1 , wherein the attenuator/amplitude tuner comprises a voltage divider or an active transistor-based circuit for attenuation.

4. The system of claim 3 , wherein an amplitude tuner is merged with an attenuator, and the amplitude tuner comprises two varactors.

5. The system of claim 1 , wherein the buffer comprises high breakdown transistors.

6. The system of claim 1 , wherein a load impedance of the buffer can be varied to provide additional amplitude tuning.

7. The system of claim 2 , wherein the phase shifter assigns different weights to I and Q signals.

8. The system of claim 7 , wherein the phase shifter combines the I and Q signals to provide the cancellation signal.

9. The system of claim 1 , wherein the transmitter and the receiver are components of a single-chip transceiver.

10. The system of claim 9 , wherein the single-chip transceiver is part of an Electron Paramagnetic Resonance (EPR) spectrometer.

11. The system of claim 1 , wherein the cancellation signal cancels power leakage or self-interference from the transmitter.

12. An active cancellation method comprising:
receiving an output signal of a transmitter;
attenuating the output signal and tuning an amplitude of the output signal to produce a signal for cancellation of a TX self-interference signal;
buffering the signal after attenuating and tuning steps to provide additional amplitude tuning to output a buffer output signal;
phase shifting the buffer output signal 180° relative to a TX self-interference signal to provide a cancellation signal; and
outputting the cancellation signal to a receiver based on the TX self-interference signal caused by the transmitter, wherein the cancellation signal is injected after a low-noise amplifier (LNA) of the receiver to minimize a noise figure (NF) degradation of the receiver due to active cancellation circuitry.

13. The method of claim 12 , where the buffer output signal is a differential signal and the phase shifting step is implemented by receiving the differential signal and converting the differential signal into a quadrature signal;
phase shifting the quadrature signal;
combining branches of the quadrature signal to produce the cancellation signal.

14. The method of claim 12 , wherein the attenuating and the tuning of the amplitude steps are performed with an attenuator/amplitude tuner that comprises a voltage divider.

15. The method of claim 14 , wherein an amplitude tuner is merged with an attenuator, the amplitude tuner comprises two varactors.

16. The method of claim 12 , wherein the buffering is performed with a buffer comprising high breakdown transistors.

17. The method of claim 12 , wherein a load impedance of a buffer providing the buffering can be varied to provide additional amplitude tuning.

18. The method of claim 13 , wherein the phase shifting step assigns different weights to I and Q signals.

19. The method of claim 18 , wherein the phase shifting combines the I and Q signals to provide the cancellation signal.

20. The method of claim 12 , wherein the transmitter and the receiver are components of a single-chip transceiver.

21. The method of claim 20 , wherein the single-chip transceiver is part of an Electron Paramagnetic Resonance (EPR) spectrometer.

22. The method of claim 12 , wherein the cancellation signal cancels power-leakage or self-interference from the transmitter.

Assignees

• Univ Rice William M

Inventors

• Babakhani Aydin
• Yang Xuebei

Classifications

• G01R33/60 Primary

  using electron paramagnetic resonance (G01R33/24, G01R33/62 take precedence) · CPC title

• G01R33/24

  for measuring direction or magnitude of magnetic fields or magnetic flux · CPC title

• G01R33/3607 Primary

  RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal · CPC title

• G01R33/62

  using double resonance (G01R33/24 takes precedence) · CPC title

• G01R33/64

  using cyclotron resonance (G01R33/24 takes precedence) · CPC title