Mobile wireless communications device including sensing transistor and hysteretic comparator and related methods

• US 8,494,468 B1
• Filed: 01/27/2012
• Issued: 07/23/2013
• Est. Priority Date: 01/27/2012
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: Muhammad, Khurram, Ryu, Seong-Ryong
• Primary Examiner(s): SMITH, CREIGHTON H
• Application Number:
  US13/360,414
• Publication Number:
  US 20130196719A1
• Time in Patent Office: 543 Days
• Field of Search: 455/195.1, 455/108, 330/136
• US Class Current: 455/195.1
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2200/432 Two or more amplifiers of different type are coupled in parallel at the input or output, e.g. a class D and a linear amplifier, a class B and a class A amplifier
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/462 the current being sensed
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/2173 of the bridge type
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/04 Circuits

Abstract

A mobile wireless communications device may include a portable housing, and a supply modulator carried by the portable housing. The supply modulator may include an output node, a linear amplifier coupled to the output node, and a switching amplifier also coupled to the output node. The switching amplifier may include at least one sensing transistor configured to sense current output from the linear amplifier and generate a drive voltage, and a hysteretic comparator coupled to the at least one sensing transistor and configured to be driven by the drive voltage. The mobile wireless communications device may also include a radio frequency (RF) power amplifier coupled to the output node of the supply modulator, and a wireless transceiver carried by the portable housing and coupled to the RF power amplifier.

Claims

1. A mobile wireless communications device comprising:

a portable housing;

a supply modulator carried by said portable housing and comprising

an output node,

a linear amplifier coupled to said output node, and

a switching amplifier also coupled to said output node and comprising

at least one sensing transistor configured to sense current output from said linear amplifier and generate a drive voltage, and

a hysteretic comparator coupled to said at least one sensing transistor and configured to be driven by the drive voltage;

a radio frequency (RF) power amplifier coupled to said output node of said supply modulator; and

a wireless transceiver carried by said portable housing and coupled to said RF power amplifier.

2. The mobile wireless communications device of claim 1, wherein said switching amplifier further comprises at least one current conveyor circuit coupled to said at least one sensing transistor and configured to control a bias of said at least one sensing transistor.

3. The mobile wireless communications device of claim 1, wherein said linear amplifier comprises an operational transconductance amplifier and at least one transistor coupled thereto.

4. The mobile wireless communications device of claim 1, wherein said switching amplifier further comprises a buffer coupled between said hysteretic comparator and said output node.

5. The mobile wireless communications device of claim 4, wherein said buffer comprises a pair of transistors having respective control terminals coupled to each other.

6. The mobile wireless communications device of claim 4, wherein said switching amplifier further comprises at least one inductor coupled between said output node and said buffer.

7. The mobile wireless communications device of claim 1, wherein said wireless transceiver comprises a cellular transceiver.

8. A supply modulator to be carried by a portable housing of a mobile wireless communications device comprising a radio frequency (RF) power amplifier and a wireless transceiver carried by the portable housing and coupled to the RF power amplifier, the supply modulator comprising:

an output node coupled to be coupled to the RF power amplifier;

a linear amplifier coupled to said output node; and

a switching amplifier also coupled to said output node and comprising

at least one sensing transistor configured to sense current output from said linear amplifier and generate a drive voltage, and

a hysteretic comparator coupled to said at least one sensing transistor and configured to be driven by the drive voltage.

9. The supply modulator of claim 8, wherein said switching amplifier further comprises at least one current conveyor circuit coupled to said at least one sensing transistor and configured to control a bias of said at least one sensing transistor.

10. The supply modulator of claim 8, wherein said linear amplifier comprises an operational transconductance amplifier and at least one transistor coupled thereto.

11. The supply modulator of claim 8, wherein said switching amplifier further comprises a buffer coupled between said hysteretic comparator and said output node.

12. The supply modulator of claim 11, wherein said buffer comprises a pair of transistors having respective control terminals coupled to each other.

13. The supply modulator of claim 11, wherein said switching amplifier further comprises at least one inductor coupled between said output node and said buffer.

14. A method of operating a supply modulator for a power amplifier of a mobile wireless communications device, the supply modulator comprising an output node, a linear amplifier coupled to the output node, and a switching amplifier coupled to the linear amplifier, method comprising:

using the switching amplifier to

sense current output from the linear amplifier via at least one sensing transistor,

generate a drive voltage via the at least one sensing transistor, and

drive a hysteretic comparator coupled to the at least one sensing transistor with the drive voltage.

15. The method of claim 14, wherein the switching amplifier further comprises at least one current conveyor circuit coupled to the at least one sensing transistor;

and wherein the switching amplifier is used to control a bias of the at least one sensing transistor.

16. The method of claim 14, wherein the switching amplifier further comprises a buffer coupled between the hysteretic comparator and the output node.

17. The method of claim 16, wherein the buffer comprises a pair of transistors having respective control terminals coupled to each other.

18. The method of claim 16, wherein the switching amplifier further comprises at least one inductor coupled between the output node and the buffer.