Programmable ultrasound transmit beamformer integrated circuit and method

• US 8,013,640 B1
• Filed: 06/12/2009
• Issued: 09/06/2011
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Supertex Incorporated (Microchip Technology Incorporated)
• Inventors: Chu, Ching
• Primary Examiner(s): Donovan; Lincoln
• Assistant Examiner(s): JAGER, RYAN C
• Application Number:
  US12/484,107
• Time in Patent Office: 816 Days
• Field of Search: 327/106
• US Class Current: 327/106
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

An electrical waveform generating circuit has a programmable current source-driver. A digital switched current source is coupled to the programmable current source-driver and controlled by waveforms stored in the programmable current source-driver. A plurality of MOSFETs is coupled to the programmable current source driver. A center-tapped RF transformer is provided and has a primary coupled to the plurality of high voltage MOSFETs. A transducer is coupled to a secondary of the RF transformer.

Claims

1. An electrical waveform generating circuit comprising:

a programmable current source-driver;

a digital switched current source coupled to the programmable current source-driver and controlled by waveforms stored in the programmable current source-driver;

a plurality of MOSFETs coupled to the programmable current source driver;

a center-tapped RF transformer having a primary coupled to the plurality of high voltage MOSFETs;

a transducer coupled to a secondary of the RF transformer.

2. An electrical waveform generating circuit in accordance with claim 1 wherein the plurality of high voltage MOSFETs comprises:

a first pair of MOSFETS, wherein source terminals of each of the first pair of MOSFETS is coupled to the digital switched current source;

a second pair of MOSFETS, wherein the drain terminals of the first pair of MOSFETS are driving the source terminals of the second pair of MOSFETS, the gate terminals of the second pair of MOSFETS grounded for AC point of view and connected to a MOSFET voltage supply.

3. An electrical waveform generating circuit in accordance with claim 2 further comprising a pair of protection diodes, wherein the pair of protection diodes is coupled between the first pair of MOSFETs and the second pair of MOSFETs.

4. An electrical waveform generating circuit in accordance with claim 1 wherein the programmable current source-driver comprises:

a waveform memory coupled to the digital switched current source to control the switching current control circuit;

a digital to analog converter (DAC) coupled to the digital switched current source for setting-up full scale currents of the digital switched current source; and

a waveform memory which controls the switching current control circuit and can be read and write accessed via the plurality of pins of the serial port interface.

5. An electrical waveform generating circuit in accordance with claim 4 wherein the programmable current source-driver further comprises:

a serial port interface coupled DAC and the waveform generator to read and write data to the waveform memory;

control logic coupled to the serial port interface and the waveform memory; and

an address generator coupled to the serial port interface, to the control logic and to the waveform memory.

6. An electrical waveform generating circuit in accordance with claim 5 wherein the serial port interface has control registers for storing programmable features.

7. An electrical waveform generating circuit in accordance with claim 5 further comprising a transmitting frequency pre-scale being coupled to the serial port interface.

8. An electrical waveform generating circuit in accordance with claim 5 further wherein the diodes are Schottky type of fast reverse recovery diodes connected at a source driver output to power supply voltage rail to protect the output device of the source driver.

9. An electrical waveform generating circuit in accordance with claim 4 wherein the waveform memory comprises:

a sine-cosine look-up table coupled to the digital switched current source; and

a PWM control data memory coupled to the sine-cosine look-up table.

10. An electrical waveform generating circuit in accordance with claim 5 wherein the waveform memory comprises:

a sine-cosine look-up table coupled to the digital switched current source; and

a PWM control data memory coupled to the sine-cosine look-up table, the address generator, the serial port interface and the control logic.

11. An electrical waveform generating circuit in accordance with claim 1 further comprising a pair of resistive elements in parallel with the primarily of the transformer to absorb energy in a winding leakage inductance of the transformer.

12. An electrical waveform generating circuit in accordance with claim 1 further comprising a plurality of de-coupling capacitors, at least one de-coupling capacitor coupled to each power supply voltage in the electrical waveform generating circuit.

13. An electrical waveform generating circuit in accordance with claim 1 further comprising bypass capacitors coupled to the plurality of MOSFETS.

14. An electrical waveform generating circuit comprising:

a programmable current source-driver;

a digital switched current source coupled to the programmable current source-driver and controlled by waveforms stored in the programmable current source-driver;

a first pair of MOSFETS, wherein source terminals of each of the first pair of MOSFETS is coupled to the digital switched current source;

a second pair of MOSFETS, wherein the drain terminals of the first pair of MOSFETS are driving the source terminals of the second pair of MOSFETS, the gate terminals of the second pair of MOSFETS grounded for AC point of view and connected to a MOSFET voltage supply;

a pair of protection diodes, wherein the pair of protection diodes is coupled between the first pair of MOSFETs and the second pair of MOSFETs;

a center-tapped RF transformer having a primary coupled to the second pair of MOSFETs;

a transducer coupled to a secondary of the RF transformer.

15. An electrical waveform generating circuit in accordance with claim 14 wherein the programmable current source-driver comprises:

a waveform memory coupled to the digital switched current source to control the switching current control circuit;

a digital to analog converter (DAC) coupled to the digital switched current source for setting-up full scale currents of the digital switched current source; and

a waveform memory which controls the switching current control circuit and can be read and write accessed via the plurality of pins of the serial port interface.

16. An electrical waveform generating circuit in accordance with claim 15 wherein the programmable current source-driver further comprises:

a serial port interface coupled DAC and the waveform generator to read and write data to the waveform memory;

control logic coupled to the serial port interface and the waveform memory; and

an address generator coupled to the serial port interface, to the control logic and to the waveform memory.

17. An electrical waveform generating circuit in accordance with claim 16 further comprising a transmitting frequency pre-scale being coupled to the serial port interface.

18. An electrical waveform generating circuit in accordance with claim 15 wherein the waveform memory comprises:

a sine-cosine look-up table coupled to the digital switched current source; and

a PWM control data memory coupled to the sine-cosine look-up table.

19. An electrical waveform generating circuit in accordance with claim 16 wherein the waveform memory comprises:

a sine-cosine look-up table coupled to the digital switched current source; and

a PWM control data memory coupled to the sine-cosine look-up table, the address generator, the serial port interface and the control logic.

20. An electrical waveform generating circuit in accordance with claim 14 further comprising a pair of resistive elements in parallel with the primarily of the transformer to absorb energy in a winding leakage inductance of the transformer.