WO1997044894A1 - Error path control for feed-forward amplifier - Google Patents
Error path control for feed-forward amplifier Download PDFInfo
- Publication number
- WO1997044894A1 WO1997044894A1 PCT/US1997/002367 US9702367W WO9744894A1 WO 1997044894 A1 WO1997044894 A1 WO 1997044894A1 US 9702367 W US9702367 W US 9702367W WO 9744894 A1 WO9744894 A1 WO 9744894A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- feed
- forward amplifier
- error
- carrier
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3223—Modifications of amplifiers to reduce non-linear distortion using feed-forward
- H03F1/3229—Modifications of amplifiers to reduce non-linear distortion using feed-forward using a loop for error extraction and another loop for error subtraction
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/451—Indexing scheme relating to amplifiers the amplifier being a radio frequency amplifier
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2201/00—Indexing scheme relating to details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements covered by H03F1/00
- H03F2201/32—Indexing scheme relating to modifications of amplifiers to reduce non-linear distortion
- H03F2201/3212—Using a control circuit to adjust amplitude and phase of a signal in a signal path
Definitions
- the present invention relates generally to feed- forward amplifiers and more particularly, to controlling an error path in a feed-forward amplifier.
- the methods used to tune the error path in feed ⁇ forward amplifiers have limitations imposed by the dynamic range of the detector used to form the basis for controlling the error path.
- the input level to the pilot tone receiver must be maintained at a sufficiently low level to ensure that the IM generated in the pilot tone receiver is below that of the corrected LPA. While this is not very difficult to overcome in relaxed intermodulation (IM) product environments, strict IM products requirements can present a more difficult problem.
- IM intermodulation
- FIG. 1 Such a prior art feed ⁇ forward amplifier is shown in FIG. 1.
- a signal 101 is input into a radio frequency (RF) coupler 103 which has as an output a signal entering a main gain /phase control block 106.
- Output from the block 106 is input into a main amp 109 which has an output into another RF coupler 112.
- the main amp 109 is a Class AB amplifier as is well known in the art.
- the main gain /phase control block 106 and the main amp 109 generally comprise a main path 107 for the signal 101 to propagate.
- the amount of time delay presented by the main delay block 115 is approximately equal to the amount of time delay the input signal 101 experiences as it propagates through the main path 107.
- the signal exiting the main delay block 115 enters RF coupler 118.
- Also input into RF coupler 118 is an output from RF coupler 112. Since each signal entering RF coupler 118 is substantially in phase, the main signal component in each of the input signals will be canceled, thus leaving
- the error signal 119 exiting the RF coupler 118 is input into an error path 123 which generally comprises an error gain/phase control 121 and an error amplifier 124.
- the error amp 124 is a Class A amplifier as is well known in the art.
- the error gain /phase control block 121 provides fine tune adjustment of both the gain and the phase of the error signal 119 exiting the RF coupler 118. Exiting the error amp 124 is thus an error signal which has been gain and phase controlled by a controller 137.
- the controller 137 includes a down converter 139 and an analog-to-digital (A/D) 136.
- the signal exiting the RF coupler 127 is a signal which contains both a main signal component and an error component, and this signal is input into an error delay block 127 which provides a time delay which is substantially equal to the time delay the error signal 119 experiences as it propagates through the error path 123.
- the signal exiting the error delay block 127 is input into the RF coupler 130, as is the gain and phase controlled error signal exiting the error amplifier 124. Again, since each signal entering the RF coupler 130 is in phase, the two signals entering the RF coupler 130 will be combined such that the error signal is substantially canceled.
- the signal 131 exiting the RF coupler 130 has (theoretically) only the main component of the original input signal therein.
- Signal 131 is input into the RF coupler 133 which provides not only the eventual output signal but also a signal 134 used by the controller 137 to eventually control the error path 123.
- A/D converter 136 to control the error path 123 is required.
- the A/D converter 136 must be a minimum of a 12-bit A/D converter.
- the down conversion process would also be required to have IM performance more than the desired IM performance of the overall feed-forward LPA - typically -60 dBc IM performance for the AMPS cellular band.
- FIG. 1 generally depicts a prior art feed-forward amplifier.
- FIG. 2 generally depicts a feed-forward amplifier having improved error path control in accordance with the invention.
- FIG. 3 generally depicts an alternate embodiment of a feed-forward amplifier having improved error path control in accordance with the invention.
- a feed-forward amplifier bases control of an error path within the feed-forward amplifier on an output signal after performing carrier cancellation to remove the carrier signal.
- the feed-forward amplifier implements couplers, a carrier cancellation gain /phase control block and a carrier cancellation delay block to cancel the carrier signal.
- FIG. 2 generally depicts a feed-forward amplifier 200 having improved error path control in accordance with the invention.
- FIG. 2 has a substantial number of blocks in common with FIG. 1, and thus like blocks are identified with like numerals. Different from FIG.
- a means for canceling 207 the carrier signal such means including the RF coupler 203, a carrier cancellation gain /phase control block 206, a carrier cancellation block 209 and another RF coupler 212.
- the signal coupled off of the RF coupler 133 is not directly input into the means for controlling 216, but is instead input into the RF coupler 212.
- the signal 219 exiting the RF coupler 212 does not have the main component of the input signal (i.e., the carrier signal) therein. In fact, the signal exiting the RF coupler 212 has only an error signal therein.
- the means for controlling 216 of FIG. 2 no longer suffers from the effects of a wide dynamic control signal as in the prior art.
- A/D converter 215 can be implemented as a much smaller A/D converter.
- an 8- bit converter can thus be implemented to provide improved control of the error path in accordance with the invention.
- FIG. 3 generally depicts an alternate embodiment of a feed-forward amplifier having improved error path control in accordance with the invention.
- a switchable attenuator 303 is implemented to disable the means for canceling 207 from the circuitry, thus allowing for easy identification of the desired carrier frequencies.
- the desired carriers will be much larger than the IM products and thus easily identifiable for use in subsequent intermodulation (IM) product determination.
- IM intermodulation
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU19595/97A AU1959597A (en) | 1996-05-17 | 1997-02-13 | Error path control for feed-forward amplifier |
JP9542314A JPH11509716A (en) | 1996-05-17 | 1997-02-13 | Method and apparatus for improving the error path control of a forward amplifier |
EP97907638A EP0839405A1 (en) | 1996-05-17 | 1997-02-13 | Error path control for feed-forward amplifier |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US64935796A | 1996-05-17 | 1996-05-17 | |
US08/649,357 | 1996-05-17 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997044894A1 true WO1997044894A1 (en) | 1997-11-27 |
Family
ID=24604442
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1997/002367 WO1997044894A1 (en) | 1996-05-17 | 1997-02-13 | Error path control for feed-forward amplifier |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0839405A1 (en) |
JP (1) | JPH11509716A (en) |
KR (1) | KR19990022835A (en) |
AU (1) | AU1959597A (en) |
CA (1) | CA2227313A1 (en) |
WO (1) | WO1997044894A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6456160B1 (en) | 1999-09-01 | 2002-09-24 | Mitsubishi Denki Kabushiki Kaisha | Feedforward amplifier |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4389618A (en) * | 1981-04-15 | 1983-06-21 | The United States Of America As Represented By The Secretary Of The Navy | Adaptive feed-forward system |
GB2167256A (en) * | 1984-11-17 | 1986-05-21 | Racal Communications Equip | Feedforward amplifiers |
US5485120A (en) * | 1994-07-28 | 1996-01-16 | Aval Communications Inc. | Feed-forward power amplifier system with adaptive control and control method |
US5570063A (en) * | 1995-05-18 | 1996-10-29 | Spectrian, Inc. | RF power amplifier with signal predistortion for improved linearity |
-
1997
- 1997-02-13 EP EP97907638A patent/EP0839405A1/en not_active Withdrawn
- 1997-02-13 KR KR1019970709304A patent/KR19990022835A/en not_active Application Discontinuation
- 1997-02-13 WO PCT/US1997/002367 patent/WO1997044894A1/en not_active Application Discontinuation
- 1997-02-13 CA CA002227313A patent/CA2227313A1/en not_active Abandoned
- 1997-02-13 AU AU19595/97A patent/AU1959597A/en not_active Abandoned
- 1997-02-13 JP JP9542314A patent/JPH11509716A/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4389618A (en) * | 1981-04-15 | 1983-06-21 | The United States Of America As Represented By The Secretary Of The Navy | Adaptive feed-forward system |
GB2167256A (en) * | 1984-11-17 | 1986-05-21 | Racal Communications Equip | Feedforward amplifiers |
US5485120A (en) * | 1994-07-28 | 1996-01-16 | Aval Communications Inc. | Feed-forward power amplifier system with adaptive control and control method |
US5570063A (en) * | 1995-05-18 | 1996-10-29 | Spectrian, Inc. | RF power amplifier with signal predistortion for improved linearity |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6456160B1 (en) | 1999-09-01 | 2002-09-24 | Mitsubishi Denki Kabushiki Kaisha | Feedforward amplifier |
Also Published As
Publication number | Publication date |
---|---|
AU1959597A (en) | 1997-12-09 |
CA2227313A1 (en) | 1997-11-27 |
KR19990022835A (en) | 1999-03-25 |
EP0839405A1 (en) | 1998-05-06 |
JPH11509716A (en) | 1999-08-24 |
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