Radio frequency (RF) transmit system for digital RF current source

Patent metadata

Field	Value
Publication number	US-10591560-B2
Application number	US-201715708620-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Sep 21, 2016
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

Example embodiments include a radio frequency (RF) transmit system for a digital RF current source, the system including a magnetic resonance imaging (MRI) system control console operably connected to at least one digital RF current source amplifier. The at least one digital RF current source amplifier is operably connected to an RF transmission coil. The MRI system control console provides a digital control signal to the at least one digital RF current source amplifier. The MRI system control console provides a master RF current source clock signal to the at least one digital RF current source amplifier. The digital RF current source amplifier provides an alternating current to the RF transmission coil.

First claim

What is claimed is:

1. A digital radio frequency (RF) current source for a magnetic resonance imaging (MRI) system, the digital RF current source comprising:
a plurality of class D amplifiers, where a member of the plurality of class D amplifiers has a first terminal and a second terminal, where the member of the plurality of class D amplifiers is configured to operate as a switch, and where the member of the plurality of class D amplifiers is configured to receive a digital input signal at the first terminal, where the digital input signal is a dithered input signal or a noise-shaped input signal;
a plurality of transmission lines, where a member of the plurality of transmission lines has a length, and where the member of the plurality of transmission lines is electrically connected to the member of the plurality of class D amplifiers at the second terminal; and
an MRI RF coil configured to transmit or receive an RF signal;
where the plurality of class D amplifiers is electrically coupled in parallel to the MRI RF coil with the plurality of transmission lines.

2. The digital RF current source of claim 1 , where a first member of the plurality of class D amplifiers is configured to be controlled independently of a second, different member of the plurality of class D amplifiers.

3. The digital RF current source of claim 2 , where a member of the plurality of class D amplifiers, upon receiving a digital input having a first value, is controlled to enter a first position.

4. The digital RF current source of claim 3 , where the member of the plurality of class D amplifiers, upon being controlled to enter the first position, receives a positive DC voltage.

5. The digital RF current source of claim 4 , where the member of the plurality of class D amplifiers, upon receiving a digital input having a second, different value, is controlled to enter a second, different position, and where the member of the plurality of class D amplifiers, upon being controlled to enter the second, different position, is connected to ground.

6. The digital RF current source of claim 5 , where the member of the plurality of class D amplifiers, upon receiving a digital input having a third, different value, is controlled to enter a third, different position, and where the member of the plurality of class D amplifiers, upon being controlled to enter the third, different position, receives a negative DC voltage.

7. The digital RF current source of claim 4 , where the member of the plurality of class D amplifiers, upon receiving a digital input having a second, different value, or a third different value, is controlled to enter a second, different position, where the member of the plurality of class D amplifiers, upon being controlled to enter the second, different position, is connected to ground.

8. The digital RF current source of claim 1 , where the length of a member of the plurality of transmission lines is one quarter wavelength (λ/4) of the RF signal or an odd integer multiple of λ/4 of the RF signal.

9. The digital RF current source of claim 8 , where the length of a first member of the plurality of transmission lines is within a threshold of the length of a second member of the plurality of transmission lines, and where a phase delay between the plurality of class D amplifiers is a function of the length.

10. The digital RF current source of claim 8 , where the member of the plurality of transmission lines is a co-axial cable.

11. A digital radio frequency (RF) current source for a magnetic resonance imaging (MRI) system, the digital RF current source comprising:
a noise source;
a dithering component electrically coupled to the noise source, where the dithering component generates a dithered RF input signal by combining noise received from the noise source with an RF input signal;
an analog-to-digital converter (ADC) configured to receive the dithered RF input signal, where the ADC has a range and a reference, and where the ADC generates a sampled signal by sampling the dithered RF input signal;
a noise shaping filter electrically connected to the ADC, where the noise shaping filter generates a noise shaped signal based, at least in part, on the sampled signal;
an ADC to digital input decoder electrically connected to the noise shaping filter, where the ADC to digital input decoder converts the noise shaped signal to a digital input signal;
a plurality of class D amplifiers electrically connected in parallel to the ADC to digital input decoder, where a member of the plurality of class D amplifiers has a first terminal and a second terminal, where the member of the plurality of class D amplifiers is configured to operate as a switch, where the member of the plurality of class D amplifiers is configured to receive the digital input signal at the first terminal, and where a first member of the plurality of class D amplifiers is configured to be controlled independently of a second, different member of the plurality of class D amplifiers;
a plurality of transmission lines, where a member of the plurality of transmission lines has a length, and where the member of the plurality of transmission lines is electrically connected to the member of the plurality of class D amplifiers at the second terminal; and
an MRI RF coil configured to transmit or receive an RF signal;
where the plurality of class D amplifiers is electrically coupled in parallel to the MRI RF coil with the plurality of transmission lines.

12. The digital RF current source of claim 11 , where the ADC adjusts the range and reference based, at least in part, on the negative maximum amplitude of the dithered RF input signal or the positive maximum amplitude of the dithered RF input signal.

13. The digital RF current source of claim 11 , where a member of the plurality of class D amplifiers, upon receiving a digital input having a first value, is controlled to enter a first position.

14. The digital RF current source of claim 13 , where the member of the plurality of class D amplifiers, upon being controlled to enter the first position, receives a positive DC voltage.

15. The digital RF current source of claim 11 , where the member of the plurality of class D amplifiers, upon receiving a digital input having a second, different value, is controlled to enter a second, different position, and where the member of the plurality of class D amplifiers, upon being controlled to enter the second, different position, is connected to ground.

16. The digital RF current source of claim 15 , where the member of the plurality of class D amplifiers, upon receiving a digital input having a third, different value, is controlled to enter a third, different position, and where the member of the plurality of class D amplifiers, upon being controlled to enter the third, different position, receives a negative DC voltage.

17. The digital RF current source of claim 11 , where the length of a member of the plurality of transmission lines is one quarter wavelength (λ/4) of the RF signal or an odd integer multiple of λ/4 of the RF signal.

18. The digital RF current source of claim 17 , where the length of a first member of the plurality of transmission lines is within a threshold of the length of a second member of the plurality of transmission lines, and where a phase delay between the plurality of class D amplifiers is a function of the length.

19. The digital RF current source of claim 11 , where a member of the plurality of class D amplifiers comprises an ultrasound pulser integrated circuit configured to receive the digital inp

Assignees

• Quality Electrodynamics Llc

Inventors

• Yang Xiaoyu

Classifications

• G01R33/3607

  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

• G01R33/3614 Primary

  RF power amplifiers · CPC title

• H03F3/217

  Class D power amplifiers; Switching amplifiers · CPC title

• H03F3/2175

  using analogue-digital or digital-analogue conversion (H03F3/2173 takes precedence) · CPC title

• G01R33/3415

  comprising arrays of sub-coils {, i.e. phased-array coils with flexible receiver channels} · CPC title