Direct digital synthesizer, direct digital synthesizer for transmission and detection, and MRI apparatus

• US 7,818,359 B2
• Filed: 09/18/2006
• Issued: 10/19/2010
• Est. Priority Date: 09/22/2005
• Status: Active Grant

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Yoshizawa, Nobuhiro
• Primary Examiner(s): Bullock, Jr.; Lewis A
• Assistant Examiner(s): HUGHES, KEVIN G
• Application Number:
  US11/532,686
• Publication Number:
  US 20070064834A1
• Time in Patent Office: 1,492 Days
• Field of Search: 708/290, 380/269, 348/14.13
• US Class Current: 708/290
• CPC Class Codes: G06F 1/0328 in which the phase increment is adjustable, e.g. by using an adder-accumulator
• CPC Class Codes: G06F 1/0342 for generating simultaneously two or more related waveforms, e.g. with different phase angles only

Abstract

In order to output amplitude data with the clock frequency higher than the clock frequency of phase data, the direct digital synthesizer for transmission and detection comprises: a transmitting phase for outputting a first phase data with a first clock frequency; a curtailing unit for outputting a second phase data with a second clock frequency smaller than the first clock frequency, and outputting additional data for compensating for phase information disappeared with curtailing process; an interpolating unit for outputting a third phase data with a third clock frequency larger than the first frequency by implementing interpolating process to the second phase data, and a detecting waveform for outputting amplitude data in accordance with the third phase data. The detecting signal amplitude data can be outputted with the third clock frequency higher than the second clock frequency of the second phase data transmitted.

Claims

1. A direct digital synthesizer for transmission and detection, comprising:

a transmitting phase accumulator for outputting phase data (P1) with a clock frequency f1;

a transmitting waveform LUT for outputting transmitting signal amplitude data (T) in accordance with said phase data (P1);

a curtailing device for outputting phase data (P2) with a clock frequency f2 (<

f1) by implementing curtailing process to said phase data (P1) and also outputting additional data (A) for compensating for phase information disappeared with said curtailing process;

wherein said additional data (A) is assigned the binary value indicating which phase region said phase data (P2) belongs according to ‘

00’

=0°

to 360°

, ‘

01’

=360°

to 720°

, ‘

10’

=−

360°

to −

720°

, and ‘

11’

=−

360°

to 0° and

said additional data (A) is assigned according to 360°

times an integer where ‘

00’

is integer 0, ‘

01’

is integer 2, ‘

10’

is integer −

2, and ‘

11’

is integer −

1;

an interpolating device for outputting phase data (P3) with a clock frequency f3 (>

f2) by implementing interpolating process in accordance with said phase data (P2) and said additional data (A) outputted from said curtailing device;

and a detecting waveform LUT for outputting detecting signal amplitude data (S) in accordance with said phase data (P3) outputted from said interpolating device.

2. The direct digital synthesizer according to claim 1, wherein a first space where said transmitting phase accumulator, said transmitting waveform LUT, and said curtailing device are provided is spatially separated from a second space where said interpolating device and said detecting waveform LUT are provided.

3. The direct digital synthesizer for transmission and detection according to claim 1, wherein the clock frequency f1 is 40 MHz, the phase data (P1) of clock frequency f1 is 12 bits, the transmitting signal amplitude data (T) is 14 bits, the clock frequency f2 is 10 MHz, the phase data (P2) of clock frequency f2 is 12 bits, the additional data (A) is 2 bits, the clock frequency f3 is 80 MHz, the phase data (P3) of clock frequency f3 is 12 bits, and the detecting signal amplitude data (S) is 14 bits.

14. The MRI apparatus comprising the direct digital synthesizer for transmission and detection according to claim 1.

4. A direct digital synthesizer for transmission and detection, comprising:

a transmitting phase accumulator for outputting phase data (P1) with a clock frequency 1;

a transmitting waveform LUT for outputting transmitting signal amplitude data (T) in accordance with said phase data (P1);

a difference phase accumulator for outputting difference phase data (A1) with the clock frequency f1;

an adding device for outputting phase data (P1′

) with the clock frequency f1 by adding said phase data (P1) and said difference phase data (A1);

a curtailing device for outputting phase data (P2) with a clock frequency f2 (<

f1) by implementing curtailing process to said phase data (P1′

) outputted from said adding device and also outputting additional data (A) for compensating for phase information disappeared with said curtailing process;

wherein said additional data (A) is assigned the binary value indicating which phase region said phase data (P2) belongs according to ‘

00’

=0°

to 360°

, ‘

01’

=360°

to 720°

, ‘

10’

=−

360°

to −

720°

, and ‘

11’

=−

360°

to 0° and

said additional data (A) is assigned according to 360°

times an integer where ‘

00’

is integer 0, ‘

01’

is integer 2, ‘

10’

is integer −

2, and ‘

11’

is integer −

1;

an interpolating device for outputting phase data (P3) with a clock frequency f3 (>

f2) by implementing interpolating process in accordance with said phase data (P2) and said additional data (A) outputted from said curtailing device;

and a detecting waveform LUT for outputting detecting signal amplitude data (S) in accordance with said phase data (P3) outputted from said interpolating device.

5. The direct digital synthesizer for transmission and detection according to claim 4, wherein a first space where said transmitting phase accumulator, said transmitting waveform LUT, said difference phase accumulator, and said curtailing device are provided is spatially separated from a second space where said interpolating device and said detecting waveform LUT are provided.

6. The direct digital synthesizer for transmission and detection according to claim 4 wherein, the clock frequency f1 is 40 MHz, the phase data (P1) of clock frequency f1 is 12 bits, the transmitting signal amplitude data (T) is 14 bits, the difference phase data (Δ

1) is 12 bits, the phase data (P1′

) outputted from said adding device is 12 bits, the clock frequency f2 is 10 MHz, the phase data (P2) of clock frequency f2 is 12 bits, the additional data (A) is 2 bits, the clock frequency f3 is 80 MHz, the phase data (P3) of clock frequency f3 is 12 bits, and the detecting signal amplitude data (S) is 14 bits.

17. The MRI apparatus comprising the direct digital synthesizer for transmission and detection according to claim 4.

7. A direct digital synthesizer for transmission and detection, comprising:

a transmitting phase accumulator for outputting phase data (P1) with a clock frequency f1;

a transmitting waveform LUT for outputting transmitting signal amplitude data (T) in accordance with said phase data (P1);

a curtailing device for outputting phase data (P2) with a clock frequency f2 (<

f1) by implementing curtailing process to said phase data (P1) and also outputting additional data (A) for compensating for phase information disappeared with said curtailing process;

wherein said additional data (A) is assigned the binary value indicating which phase region said phase data (P2) belongs according to ‘

00’

=0°

to 360°

, ‘

01’

=360°

to 720°

, ‘

10’

=−

360°

to −

720°

, and ‘

11’

=−

360°

to 0° and

said additional data (A) is assigned according to 360°

times an integer where ‘

00’

is integer 0, ‘

01’

is integer 2, ‘

10’

is integer −

2, and ‘

11’

is integer −

1;

a difference outputting device for outputting difference data (V2) of said phase data (P2);

an absolute value outputting device for recovering and outputting said phase data (P2) from said difference data (V2);

an interpolating device for outputting phase data (P3) with a clock frequency f3 (>

f2) by implementing interpolating process in accordance with said phase data (P2) and said additional data (A) outputted from said absolute value outputting device;

and a detecting waveform LUT for outputting detecting signal amplitude data (S) in accordance with said phase data (P3) outputted from said interpolating device.

8. The direct digital synthesizer for transmission and detection according to claim 7, wherein a first space where said transmitting phase accumulator, said transmitting waveform LUT, said curtailing device, and said difference outputting device are provided is spatially separated from a second space where said absolute value outputting device, said interpolating device, and said detecting waveform LUT are provided.

9. The direct digital synthesizer for transmission and detection according to claim 7, wherein the clock frequency f1 is 40 MHz, the phase data (P1) of clock frequency f1 is 12 bits, the transmitting signal amplitude data (T) is 14 bits, the clock frequency f2 is 10 MHz, the phase data (P2) of clock frequency f2 is 12 bits, the additional data (A) is 2 bits, the clock frequency f3 is 80 MHz, the phase data (P3) of clock frequency f3 is 12 bits, and detecting signal amplitude data (S) is 14 bits.

13. The direct digital synthesizer for transmission and detection according to claim 7, wherein said difference outputting device is an MRI (Magnetic Resonance Imaging) apparatus which outputs difference data only in the predetermined period including the detecting period.

15. The MRI apparatus comprising the direct digital synthesizer for transmission and detection according to claim 7.

10. A direct digital synthesizer for transmission and detection, comprising:

a transmitting phase accumulator for outputting phase data (P1) with a clock frequency f1;

a transmitting waveform LUT for outputting transmitting signal amplitude data (T) in accordance with said phase data (P1);

a difference phase accumulator for outputting difference data (A1) with the clock frequency f1;

an adding device for outputting phase data (P1′

) with the clock frequency f1 by adding said phase data (P1) and said difference phase data (A1);

an curtailing device for outputting phase data (P2) with a clock frequency f2 (<

f1) by implementing curtailing process to said phase data (P1′

) outputted from said adding device and also outputting additional data (A) for compensating for phase information disappeared with said curtailing process;

wherein said additional data (A) is assigned the binary value indicating which phase region said phase data (P2) belongs according to ‘

00’

=0°

to 360°

, ‘

01’

=360°

to 720°

, ‘

10’

=−

360°

to −

720°

, and ‘

11’

=−

360°

to 0° and

said additional data (A) is assigned according to 360°

times an integer where ‘

00’

is integer 0, ‘

01’

is integer 2, ‘

10’

is integer −

2, and ‘

11’

is integer −

1;

a difference outputting device for outputting difference data (V2) of said phase data (P2);

an absolute value outputting device for recovering and outputting said phase data (P2) from said difference data (V2);

an interpolating device for outputting phase data (P3) with a clock frequency f3 (>

f2) by implementing curtailing process in accordance with said phase data (P2) and said additional data (A) outputted from said absolute value outputting device;

and a detecting waveform LUT for outputting detecting signal amplitude data (S) in accordance with said phase data (P3) outputted from said interpolating device.

11. The direct digital synthesizer for transmission and detection according to claim 10, wherein a first space where said transmitting phase accumulator, said transmitting waveform LUT, said difference phase accumulator, said curtailing device, and said difference outputting device are provided is spatially separated from a second space where said absolute value outputting device, said interpolating device, and said detecting waveform LUT are provided.

12. The direct digital synthesizer for transmission and detection according to claim 10, wherein the clock frequency f1 is 40 MHz, the phase data (P1) of clock frequency f1 is 12 bits, the transmitting signal amplitude data (T) is 14 bits, the difference phase data (Δ

1) is 12 bits, the phase data (P1′

) outputted from said adding device is 12 bits, the clock frequency f2 is 10 MHz, the phase data (P2) of clock frequency f2 is 12 bits, the additional data (A) is 2 bits, the clock frequency f3 is 80 MHz, the phase data (P3) of clock frequency f3 is 12 bits, and the detecting signal amplitude data (S) is 14 bits.

16. The direct digital synthesizer for transmission and detection according to claim 10, wherein said difference outputting device is an MRI (Magnetic Resonance Imaging) apparatus which outputs difference data only in the predetermined period including the detecting period.

18. The MRI apparatus comprising the direct digital synthesizer for transmission and detection according to claim 10.