RF power device having voltage controlled linearity

• US 5,898,198 A
• Filed: 08/06/1997
• Issued: 04/27/1999
• Est. Priority Date: 08/04/1997
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Spectrian Corp. (REMEC, Inc.)
• Inventors: Bartlow, Howard D., Herbert, Francois, Ng, Daniel, Parker, James R.
• Primary Examiner(s): MEIER, STEPHEN D
• Application Number:
  US08/906,741
• Time in Patent Office: 629 Days
• Field of Search: 257/319, 257/401, 257/316, 257/331
• US Class Current: 257/319
• CPC Class Codes: H01L 23/552 Protection against radiation, e.g. light or electromagnetic waves
• CPC Class Codes: H01L 23/585 comprising conductive layers or plates or strips or rods or rings H01L23/60, H01L23/62, H01L23/64, H01L23/66 take precedence
• CPC Class Codes: H01L 27/088 the components being field-effect transistors with insulated gate
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/7801 DMOS transistors, i.e. MISFETs with a channel accommodating body or base region adjoining a drain drift region lateral high-voltage MISFETs with channel well and drain offset region H01L29/7835
• CPC Class Codes: H01L 29/7816 Lateral DMOS transistors, i.e. LDMOS transistors
• CPC Class Codes: H01L 29/7835 with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A linear MOSFET device includes a shield plate positioned between a drain and an overlying gate. A voltage bias is applied to the shield plate to maintain linear operation of the device for RF power amplification. An AC ground is preferably connected to the shield plate. The voltage bias can be varied for matching of parallel connected devices, for responding to peak input signals, and for temperature compensation.

Claims

1. A linear MOSFET device comprising:

a semiconductor body having a major surface,

a source region of first conductivity-type abutting said surface,

a drain region of said first conductivity-type abutting said surface and spaced from said source region by a channel,

a control gate overlying said channel and part of said drain and insulated therefrom by a dielectric material,

a shield plate positioned between said gate and said drain and insulated therefrom, said shield plate underlying the gate with no overlap of the channel and positioned between the gate and drain to provide vertical shielding between the gate and the drain, and

a voltage source connected to said shield plate for providing a voltage bias thereto to increase the linearity of device operation by providing an effective AC ground.

2. The linear MOSFET device as defined by claim 1 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

3. The linear MOSFET device as defined by claim 1 wherein said channel is of second conductivity type opposite to said first conductivity type.

4. A linear MOSFET device as defined by claim 1 wherein said voltage source comprises a variable DC voltage source.

5. The linear MOSFET device as defined by claim 4 and further including an AC ground connection to said shield plate.

6. The linear MOSFET device as defined by claim 5 and further including a peak envelope detector coupled to a signal input to said gate and coupled to said shield plate, whereby DC voltage on the shield plate is changed in response to peak input signals.

7. The linear MOSFET device as defined by claim 5 and including at least one additional linear MOSFET device, said devices being connected in parallel for RF power amplification, said voltage source altering DC bias voltage for matching device operation parameters.

8. The linear MOSFET device as defined by claim 5 and further including at least one additional device, said additional device formed in a semiconductor substrate, a plurality of temperature sensor in said substrate, and means coupling said temperature sensors to a voltage source to vary voltage on a shield plate of said additional device to compensate for temperature differences of said devices.

9. The linear MOSFET device as defined by claim 5 wherein said device comprises a lateral MOSFET device.

10. The linear MOSFET device as defined by claim 5 wherein said device comprises a vertical MOSFET device.

11. The linear MOSFET device as defined by claim 1 wherein said device comprises a lateral MOSFET device.

12. The linear MOSFET device as defined by claim 1 wherein said device comprises a vertical MOSFET device.

13. A linear MOSFET device comprising:

a semiconductor body,

a source region in said body,

a drain region in said body and spaced from the source region by a channel,

a gate positioned over the channel and over a portion of the drain region,

a shield plate positioned under the gate and over a portion of the drain region to reduce gate-drain capacitance but with no overlap of the channel, and

a voltage source connected to the shield plate for providing a voltage bias thereto to increase linearity of device operation by providing an effective AC ground.

14. The linear MOSFET device as defined by claim 13 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

15. The linear MOSFET device as defined by claim 13 wherein the shield plate underlies the gate and is positioned between the gate and drain and provides vertical shielding between the gate and the drain.

16. The linear MOSFET as defined by claim 13 wherein said voltage source comprises a variable DC voltage source.

17. The linear MOSFET device as defined by claim 16 and further including an AC ground connection to said shield plate.

18. The linear MOSFET device as defined by claim 17 and further including a peak envelope detector coupled to a signal input to said gate and coupled to said shield plate, whereby DC voltage on the shield plate is changed in response to peak input signals.

19. The linear MOSFET device as defined by claim 17 and including at least one additional linear MOSFET device, said devices connected in parallel for RF power amplification, said voltage source altering DC bias voltage for matching device operation parameters.

20. The linear MOSFET device as defined by claim 17 and further including at least one additional device, said device formed in a common semiconductor substrate, a plurality temperature sensor in said substrate, and means coupling temperature sensor to a voltage source to vary voltage on a shield plate of said additional device to compensate for temperature differences of said devices.

21. The linear MOSFET device as defined by claim 17 wherein said device comprises a vertical MOSFET device.

22. The linear MOSFET device as defined by claim 17 wherein said device comprises a lateral MOSFET device.

23. The linear MOSFET device as defined by claim 13 wherein said device comprises a vertical MOSFET device.

24. The linear MOSFET device as defined by claim 13 wherein said device comprises a lateral MOSFET device.

25. A linear MOSFET device comprising:

a semiconductor body having a major surface,

a source region of first conductivity-type abutting said surface,

a drain region of said first conductivity-type abutting said surface and spaced from said source region by a channel,

a gate overlying said channel and part of said drain and insulated therefrom by a dielectric material,

a shield plate positioned between said gate and said drain and insulated therefrom,

a voltage source connected to said shield plate for providing a voltage bias thereto, and

a peak envelope detector coupled to a signal input to said gate and coupled to said shield plate, whereby DC voltage on the shield plate is changed in response to peak input signals.

26. The linear MOSFET device as defined by claim 25 wherein said voltage source comprises a variable DC voltage source.

27. The linear MOSFET device as defined by claim 26 and further including an AC ground connection to said shield plate.

28. The linear MOSFET device as defined by claim 25 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

29. A linear MOSFET device comprising:

a semiconductor body having a major surface,

a source region of first conductivity-type abutting said surface,

a drain region of said first conductivity-type abutting said surface and spaced from said source region by a channel,

a gate overlying said channel and part of said drain and insulated therefrom by a dielectric material,

a shield plate positioned between said gate and said drain and insulated therefrom but with no overlap of the channel,

a voltage source connected to said shield plate for providing a voltage bias thereto to increase linearity of device operation by providing an effective AC ground, and

at least one additional linear MOSFET device, said device being connected in parallel for RF power amplification, said voltage source altering DC bias voltage for matching device operation parameters.

30. The linear MOSFET device as defined by claim 29 wherein said voltage source comprises a variable DC voltage source.

31. The linear MOSFET device as defined by claim 30 and further including an AC ground connection to said shield plate.

32. The linear MOSFET device as defined by claim 29 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

33. A linear MOSFET device comprising:

a semiconductor body having a major surface,

a source region of first conductivity-type abutting said surface,

a drain region of said first conductivity-type abutting said surface and spaced from said source region by a channel,

a gate overlying said channel and part of said drain and insulated therefrom by a dielectric material,

a shield plate positioned between said gate and said drain and insulated therefrom,

a voltage source connected to said shield plate for providing a voltage bias thereto, and

at least one additional device, said additional device formed in a semiconductor substrate, at least one temperature sensor in said substrate, and means coupling said temperature sensor to a voltage source to vary voltage on a shield plate of said additional device to compensate for temperature differences of said devices.

34. The linear MOSFET device as defined by claim 33 wherein said voltage source comprises a variable DC voltage source.

35. The linear MOSFET device as defined by claim 34 and further including an AC ground connection to said shield plate.

36. The linear MOSFET device as defined by claim 33 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

37. A linear MOSFET device comprising:

a semiconductor body,

a source region in said body,

a drain region in said body and spaced from the source region by a channel,

a gate positioned over the channel and over a portion of the drain region,

a shield plate positioned under the gate and over a portion of the drain region to reduce gate-drain capacitance,

a voltage source connected to the shield plate for providing a voltage bias thereto, and

a peak envelope detector coupled to a signal input to said gate and coupled to said shield plate, whereby DC voltage on the shield plate is changed in response to peak input signals.

38. A linear MOSFET device as defined by claim 37 wherein said voltage source comprises a variable DC voltage source.

39. The linear MOSFET device as defined by claim 38 and further including an AC ground connection to said shield plate.

40. The linear MOSFET device as defined by claim 37 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

41. A linear MOSFET device comprising:

a semiconductor body,

a source region in said body,

a drain region in said body and spaced from the source region by a channel,

a gate positioned over the channel and over a portion of the drain region,

a shield plate positioned under the gate and over a portion of the drain region to reduce gate-drain capacitance but with no overlap of the channel,

a voltage source connected to the shield plate for providing a voltage bias thereto to increase linearity of device operation by providing an effective AC ground, and

at least one additional linear MOSFET device, said devices connected in parallel for RF power amplification, said voltage source altering DC bias voltage for matching device operation parameters.

42. A linear MOSFET device as defined by claim 41 wherein said voltage source comprises a variable DC voltage source.

43. The linear MOSFET device as defined by claim 42 and further including an AC ground connection to said shield plate.

44. The linear MOSFET device as defined by claim 41 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.

45. A linear MOSFET device comprising:

a semiconductor body,

a source region in said body,

a drain region in said body and spaced from the source region by a channel,

a gate positioned over the channel and over a portion of the drain region,

a shield plate positioned under the gate and over a portion of the drain region to reduce gate-drain capacitance,

a voltage source connected to the shield plate for providing a voltage bias thereto, and

at least one additional device, said additional device formed in a semiconductor substrate, at least one temperature sensor in said substrate, and means coupling said temperature sensor to a voltage source to vary voltage on a shield plate of said additional device to compensate for temperature differences of said devices.

46. A linear MOSFET device as defined by claim 45 wherein said voltage source comprises a variable DC voltage source.

47. The linear MOSFET device as defined by claim 46 and further including an AC ground connection to said shield plate.

48. The linear MOSFET device as defined by claim 45 wherein the shield plate is on said major surface and provides lateral shielding between the gate and the drain.