High Voltage Amplification Using Low Breakdown Voltage Devices

• US 20100301943A1
• Filed: 05/28/2009
• Published: 12/02/2010
• Est. Priority Date: 05/28/2009
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Goldfarb, Marc
• Granted Patent: US 8,179,196 B2
• Time in Patent Office: Days
• US Class Current: 330/277
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers

Abstract

Methods and apparatus for amplifying signals over a wide frequency range to generate high voltage outputs feature a pair of switching modules which are connected in series. Switching modules, e.g., field-effect transistors (FETs), operate based on the voltage difference between an amplified signal and a fixed DC signal at two of their terminals, thereby generating an output waveform that has peak-to-peak voltage higher than, e.g. twice, the breakdown voltage of the transistors within the amplifier. The DC signals applied at the switching modules may be varied using an AC signal to improve the risetime of the output waveform and achieve a faster operational speed of the amplifier.

Claims

1. A method of amplifying signals, the method comprising:

applying, at two different terminals of a first switching module, a first DC signal and a first AC signal varying within a first voltage range;

applying, at two different terminals of a second switching module, a second DC signal and a second AC signal varying within a second voltage range, wherein the second voltage range includes voltage values less than or equal to the voltage values of the first voltage range;

connecting the first switching module and the second switching module in series using their respective third terminals; and

obtaining an output signal from the connected switching modules, the output signal being responsive to the voltage difference between the first DC signal and the first AC signal, and to the voltage difference between the second DC signal and the second AC signal;

wherein the output signal varies between the highest voltage value of the first range and the lowest voltage value of the second range.

2. The method of claim 1 wherein the first AC signal and the second AC signal are in-phase.

3. The method of claim 1 further comprising:

varying the voltage at the first DC signal terminal using a 180 degree phase shifted version of the first AC signal; and

varying the voltage at the second DC signal terminal using a 180 degree phase shifted version of the second AC signal.

4. The method of claim 3, wherein the 180-degree phase shifted version of the first AC signal is DC blocked.

5. The method of claim 3, wherein the 180-degree phase shifted version of the second AC signal is DC blocked.

6. The method of claim 1, wherein at least one of the first switching module and the second switching module comprises a field-effect transistor (FET).

7. The method of claim 6, wherein the first switching module is a p-type FET.

8. The method of claim 6, wherein the second switching module is an n-type FET.

9. The method of claim 1 further comprising receiving the first AC signal from an inverter amplifier.

10. The method of claim 1 further comprising receiving the second AC signal from an inverter amplifier.

11. The method of claim 9, wherein a peak-to-peak voltage of the output signal is greater than a breakdown voltage of the transistors in the inverter amplifier.

12. The method of claim 10, wherein a peak-to-peak voltage of the output signal is greater than a breakdown voltage of the transistors in the inverter amplifier.

13. An apparatus for amplifying signals, the apparatus comprising:

a first switching module including a first terminal for applying a first DC signal, a second terminal for applying a first AC signal varying within a first voltage range, and a third terminal; and

a second switching module including a first terminal for applying a second DC signal, a second terminal for applying a second AC signal varying within a second voltage range, and a third terminal, wherein the second voltage range includes voltage values less than or equal to the voltage values of the first voltage range,

wherein the first switching module and the second switching module are connected in series using their respective third terminals, and an output signal is obtained from the series-connected switching modules; and

wherein the output signal is responsive to the voltage difference between the first DC signal and the first AC signal, and to the voltage difference between the second DC signal and the second AC signal, and varies between the highest voltage value of the first range and the lowest voltage value of the second range.

14. The apparatus of claim 13 wherein the first AC signal and the second AC signal are in-phase.

15. The apparatus of claim 13, wherein:

the voltage at the first DC signal terminal is varied using a 180 degree phase shifted version of the first AC signal; and

the voltage at the second DC signal terminal is varied using a 180 degree phase shifted version of the second AC signal.

16. The apparatus of claim 15 further comprising a first capacitor for DC blocking the 180-degree phase shifted version of the first AC signal.

17. The apparatus of claim 15 further comprising a second capacitor for DC blocking the 180-degree phase shifted version of the second AC signal.

18. The apparatus of claim 13, wherein at least one of the first switching module and the second switching module comprises a field-effect transistor (FET).

19. The apparatus of claim 18, wherein the first switching module is a p-type FET.

20. The apparatus of claim 18, wherein the second switching module is an n-type FET.

21. The apparatus of claim 13, wherein the first AC signal is received from an inverter amplifier.

22. The apparatus of claim 13, wherein the second AC signal is received from an inverter amplifier.

23. The apparatus of claim 21, wherein a peak-to-peak voltage of the output signal is greater than a breakdown voltage of the transistors in the inverter amplifier.

24. The apparatus of claim 22, wherein a peak-to-peak voltage of the output signal is greater than a breakdown voltage of the transistors in the inverter amplifier.

25. A method for increasing the switching speed of a switching module, the method comprising:

applying, at two different terminals of a switching module, a DC signal and an AC signal; and

varying the voltage at the DC signal terminal using a 180 degree phase shifted version of the AC signal.

26. The method of claim 25, wherein the 180-degree phase shifted version of the AC signal is DC blocked.