WO2002052717A2 - Feed-forward amplifier loop control utilizing if signal processing - Google Patents
Feed-forward amplifier loop control utilizing if signal processing Download PDFInfo
- Publication number
- WO2002052717A2 WO2002052717A2 PCT/US2001/050336 US0150336W WO02052717A2 WO 2002052717 A2 WO2002052717 A2 WO 2002052717A2 US 0150336 W US0150336 W US 0150336W WO 02052717 A2 WO02052717 A2 WO 02052717A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- amplifier arrangement
- loop
- amplifier
- phase
- 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
- H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
-
- 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
Definitions
- the present invention relates to a feed-forward amplifier, and particularly relates to a feed-forward signal cancellation control loop therein, as
- the first is a signal
- the first method is signal adaptive and the second
- Pilot systems inject an internally
- control of the first loop i.e., the signal cancellation loop
- the signal cancellation loop is adaptive.
- a typical pilot application is to inject a pilot signal at the input of an amplifier.
- the signal is split into two paths, one active (amplified) and one passive (delayed).
- the active signal is
- design goal of the signal cancellation loop is to minimize the power at the signal
- the adaptive method may employ a power detector to detect the average level at the signal
- a micro-controller adjusts the phase and amplitude or complex
- the controller must generate a complex
- control signal (i.e., real and imaginary parts) control signal whereas only amplitude information is
- the controller must adjust phase and amplitude by trial and error to
- sampling period it is of utmost importance that the sampling period be longer than any
- the nulling algorithm will not be able to determine if
- a lower signal level is the result of a controller change or signal envelope change
- the outputs to the complex amplitude controllers are
- diodes have a definite threshold voltage and below that voltage, there is no output
- diodes such as described are used in a signal
- the loop can cancel the signal or balance the loop. This limits the dynamic range at low operating levels. Possible solutions employ the use of limiting amplifiers for at least the reference input to the loop. Although resulting in improved
- feed-forward amplifiers is the application of a pilot signal injected somewhere in
- the principle is to detect the pilot signal at the system output
- pilot is nulled when the distortion cancellation path (error amp)
- phase and amplitude response is
- the detected pilot was used as an indication of loop balance or
- pilot signal into quadrature components that could be used directly to control the gain and phase.
- the direction and amplitude of the control signals are extracted directly without computation or
- the pilot receiver output contained the two signals that represented phase and amplitude information.
- the invention uses a CW pilot that is offset form local oscillator with which the pilot is mixed.
- pilot at its offset frequency is injected into the main amplifier path.
- receiver consisting of a down converter, band pass filtered IF amplifier and
- the detector detects the pilot.
- the down converter converts the pilot signal to an IF signal at a frequency equal to the offset.
- the IF signal contains all the amplitude
- the IF signal is subjected to digital
- the detected pilot is used as an indication of loop balance or null.
- Resulting sampled signals are integrated and applied to amplitude and phase (or I and Q) controllers to adjust the magnitude and
- the invention utilizes a quadrature method for analyzing the pilot
- the pilot signal is separated into quadrature components that could be used
- a high frequency active mixer that is capable of operating above 2
- GHz is used in signal cancellation loop design.
- An example of such a device is Motorola's MC13143D chip that utilizes a dual cross-coupled differential pairs of
- Figure 1 is a block diagram of a feed-forward amplifier according to the invention, showing a signal cancellation loop and an error loop controller.
- Figure 2 is a block diagram of the signal cancellation loop which utilizes a Cartesian loop method using linear mixers.
- Figure 3 is a block diagram illustrating the error loop controller.
- Figure 4 is a schematic block diagram emphasizing the frequency spectrum for the continuous wave IF pilot signal utilized according to the present invention.
- FIG. 1 shows a feed-forward amplifier 10 according to the invention.
- RF input signal 11 is sampled by directional coupler 12 at approximately 10 dB down such that substantially all (approximately 90%) of the RF signal continues along delay line 13.
- the signal sampled by directional coupler 12 is fed to a complex (i.e., real and imaginary parts) modulator 14 and, following injection of the pilot signal from directional coupler 30, the signal is amplified at main amplifier 15.
- the RF input it continues to propagate through delay line 13 where it is sampled by directional coupler 16 where it is fed as a reference to first loop 17 which is hereinafter referred to as a signal cancellation loop.
- the output of main amplifier 15 is sampled by a sampling directional coupler 19 and coupled back into the RF input and
- the distortion component is sampled by directional coupler
- signal cancellation loop is to minimize the main signal, and it does so as described more fully below.
- the remaining signal that is essentially a distortion signal is propagated through complex modulator 22 and amplified by the error amplifier 24
- Directional coupler 26 injects typically at 10 dB
- a directional coupler 28 At the output 27 of main amplifier 15, a directional coupler 28
- the signal from directional coupler 28 functions as a pilot input signal to error loop controller 29, which controls complex
- the complex modulator 22 is
- Complex modulators 14 and 22 can be IQ modulators, or they can
- Figure 2 is a detailed block diagram of a signal cancellation
- a high frequency linear mixer 31 is used to overcome many of the
- Such device is Motorola's MC13143D chip that utilizes a dual cross coupled
- no threshold to overcome when processing signals can result in improvement of at least 10 (I O dB) in operating dynamic range over the diode method of signal mixing or detection.
- FIG. 3 is a detailed block diagram of the error loop control block
- a CW pilot signal is injected 28 into the main amplifier 15 chain. Any pilot
- the pilot signal 28 is therefore preferably injected at an intermediate stage of the main amplifier chain where there is less chance that the pilot will leak into the input of the error path.
- the pilot may also be
- the pilot is injected at 30 to 50 dB below the desired system signal
- injection levels Although other injection levels may be used, too high a level will result in excessive pilot leakage and insufficient injection level can cause inadequate loop control.
- a band-pass filter 38 attenuates the output signal in order to prevent overdriving of the mixer 39.
- the output signal is attenuated by 10 or 20 dB.
- the pilot is reduced or nulled by the control circuitry approximately another 30 dB during normal loop operation, the down converter utilized is preferably one that has a wide dynamic range.
- the IF signal typically less than 500 micro volts, is amplified and band-passed, preferably by a relatively high gain low frequency (typically 100 KHz or less) IF amplifier 33.
- a dual off the shelf operational amplifier is satisfactory for this application.
- the resulting output signal of the IF amplifier 33 is applied to two signal samplers 34 that are controlled by a digital processor controller 35.
- the signal samplers 34 are preferably CMOS analog switches driven from 5-volt logic levels, but can also be any other analog or digital switches.
- the samplers 34 extract amplitude and phase or I and Q information from the IF signal.
- the sampled signals are integrated by control integrators 40, and applied to the appropriate amplitude and phase (or I and Q controllers) to adjust the magnitude and phase of the error path to be identical to the main delay line path 35.
- Digital controller assembly 35 generates a master reference signal for use by synthesizer 36, base-band generator 41, and sampling switches 34, and
- the master reference signal is divided down to 250 KHz. This 250 KHz signal is applied to an eight-bit counter. The eight bit outputs are applied to a ROM (read only memory). An adder shifts the count by 6 bits (count of 64). This shifted eight-bit word is applied to another identical ROM. Both ROMs contain code that is a sine conversion table. Digital to analog converters output two approximately 1 KHz sine waves of equal amplitude and phase offset by 90 degrees 43. The resulting sine and cosine waveforms 43 are applied to the I and Q inputs of a vector modulator 41.
- the base-band signals 43 meet the requirements for generating a single sideband suppressed carrier or a frequency offset, which is used in the present application as the pilot signal.
- the eight bit counter and the shifted eight-bit counter output is also directed to four eight bit comparators.
- An output port of the micro-controller controls and sets the reference number.
- the micro-controller sets an eight bit number incrementing or decrementing from 0-255.
- the eight bit output of the comparators is used to drive a dual flip-flop that generates waveforms for the sampling switches.
- the micro-controller by incrementing this eight bit word reference word, allows continuous 360-degree phase adjustment between the sampling signals and the base-band signals. This phase offset adjustment allows the micro-controller to adjust timing signals so the samplers extract the proper phase and amplitude information to lock the loop.
- phase offset Once phase offset has been correctly determined, the eight bit offset number is stored in non- volatile memory in the controller to be recalled upon power on. Since timing or phase alignment process is accomplished at base-band, it is usually not required to use manual, voltage controlled RF frequency phase shifters or trimming of cable lengths to accomplish calibration. With 360-degree
- integration nodes is an indication that an individual loop (Amplitude or Phase) is
- a primary function of the micro-controller upon power-up is to
- phase offset data is sent to the adders.
- micro-controller functions of the micro-controller are an internal system
- interface is used communicate loop control system status, control external manual
- micro-controller interface functions are to shut off other system components in the event of a control loop failure and during routine calibration.
- the microcontroller takes action. If either one of the first loop (signal cancellation) status lines show an out of lock condition, the micro-controller
- main amplifier 15 will be turned on and the loop status checked again. If it is still out of lock, the main amplifier 15 is turned off. This process can be programmed
- the error amplifier 24 is turned on and loop status is again checked. If the loop is still
- the auto calibration procedure may be repeated several times as with the
- the micro-controller can provide auto calibration either on a periodic basic, on power up, upon loop lock fail and during factory alignment and
- the microcontroller Upon an external command or a status signal, the microcontroller will turn off the error amplifier 24. The two status lines will be monitored. The
- microcontroller will increment the phase offset until phase status read zero that is
- the microcontroller turns on the error amplifier 24 and monitors loop status voltages. Both voltages will drop to zero
- This process is preferably
- Figure 4 is a schematic block diagram emphasizing the frequency
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/362,755 US6897723B2 (en) | 2000-12-22 | 2001-12-21 | Feed-forward amplifier loop control utilizing if signal processing |
EP01991548A EP1346473A4 (en) | 2000-12-22 | 2001-12-21 | Feed-forward amplifier loop control utilizing if signal processing |
KR10-2003-7008378A KR20030090616A (en) | 2000-12-22 | 2001-12-21 | Feed-forward amplifier loop control utilizing if signal processing |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US25766100P | 2000-12-22 | 2000-12-22 | |
US60/257,661 | 2000-12-22 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002052717A2 true WO2002052717A2 (en) | 2002-07-04 |
WO2002052717A3 WO2002052717A3 (en) | 2003-04-03 |
Family
ID=22977213
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/050336 WO2002052717A2 (en) | 2000-12-22 | 2001-12-21 | Feed-forward amplifier loop control utilizing if signal processing |
PCT/US2001/050560 WO2002052718A2 (en) | 2000-12-22 | 2001-12-22 | Feed-forward amplifier loop control utilizing if signal processing |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/050560 WO2002052718A2 (en) | 2000-12-22 | 2001-12-22 | Feed-forward amplifier loop control utilizing if signal processing |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1346473A4 (en) |
KR (1) | KR20030090616A (en) |
CN (1) | CN1483242A (en) |
TW (1) | TW525344B (en) |
WO (2) | WO2002052717A2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1437825A1 (en) * | 2002-12-27 | 2004-07-14 | Nokia Corporation | Intermodulation product cancellation in communication systems |
CN100449938C (en) * | 2002-07-05 | 2009-01-07 | 中兴通讯股份有限公司 | Error loop self-adaptive cancellation control method for feedforward linear power amplifier |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7756493B2 (en) * | 2005-04-05 | 2010-07-13 | Powerwave Technologies, Inc. | Feed forward amplifier system and method using the pilot frequency from a positive feedback pilot generation and detection circuit to improve second loop convergence |
US20090196133A1 (en) * | 2008-02-04 | 2009-08-06 | Chia-Wei Liang | Signal processing apparatus for optical disc and method thereof |
JP2019526951A (en) * | 2016-06-10 | 2019-09-19 | エイ・ティ・アンド・ティ インテレクチュアル プロパティ アイ,エル.ピー. | Method and apparatus for use with a wireless distributed antenna system having an in-band reference signal |
CN107395163A (en) * | 2017-07-10 | 2017-11-24 | 东南大学 | The analog delay line circuit of Digital Circuit Control |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5768699A (en) * | 1995-10-20 | 1998-06-16 | Aml Communications, Inc. | Amplifier with detuned test signal cancellation for improved wide-band frequency response |
US5977826A (en) * | 1998-03-13 | 1999-11-02 | Behan; Scott T. | Cascaded error correction in a feed forward amplifier |
US6169450B1 (en) * | 1998-11-13 | 2001-01-02 | Powerwave Technologies, Inc. | Feed forward compensation using phase and time modulation |
US6275106B1 (en) * | 2000-02-25 | 2001-08-14 | Spectrian Corporation | Spectral distortion monitor for controlling pre-distortion and feed-forward linearization of rf power amplifier |
US6359508B1 (en) * | 2000-08-17 | 2002-03-19 | Spectrian Corporation | Distortion detection apparatus for controlling predistortion, carrier cancellation and feed-forward cancellation in linear RF power amplifiers |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5999048A (en) * | 1998-01-13 | 1999-12-07 | Lucent Technologies Inc. | Method and apparatus for spread spectrum pilot extraction for RF amplifiers |
US6553211B1 (en) * | 1998-08-20 | 2003-04-22 | Lucent Technologies Inc. | Method and apparatus for adjusting pilot signal relative to input signal |
-
2001
- 2001-12-21 WO PCT/US2001/050336 patent/WO2002052717A2/en not_active Application Discontinuation
- 2001-12-21 CN CNA018211461A patent/CN1483242A/en active Pending
- 2001-12-21 TW TW090132096A patent/TW525344B/en not_active IP Right Cessation
- 2001-12-21 EP EP01991548A patent/EP1346473A4/en not_active Withdrawn
- 2001-12-21 KR KR10-2003-7008378A patent/KR20030090616A/en not_active Application Discontinuation
- 2001-12-22 WO PCT/US2001/050560 patent/WO2002052718A2/en not_active Application Discontinuation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5768699A (en) * | 1995-10-20 | 1998-06-16 | Aml Communications, Inc. | Amplifier with detuned test signal cancellation for improved wide-band frequency response |
US5977826A (en) * | 1998-03-13 | 1999-11-02 | Behan; Scott T. | Cascaded error correction in a feed forward amplifier |
US6169450B1 (en) * | 1998-11-13 | 2001-01-02 | Powerwave Technologies, Inc. | Feed forward compensation using phase and time modulation |
US6275106B1 (en) * | 2000-02-25 | 2001-08-14 | Spectrian Corporation | Spectral distortion monitor for controlling pre-distortion and feed-forward linearization of rf power amplifier |
US6359508B1 (en) * | 2000-08-17 | 2002-03-19 | Spectrian Corporation | Distortion detection apparatus for controlling predistortion, carrier cancellation and feed-forward cancellation in linear RF power amplifiers |
Non-Patent Citations (1)
Title |
---|
See also references of EP1346473A2 * |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100449938C (en) * | 2002-07-05 | 2009-01-07 | 中兴通讯股份有限公司 | Error loop self-adaptive cancellation control method for feedforward linear power amplifier |
EP1437825A1 (en) * | 2002-12-27 | 2004-07-14 | Nokia Corporation | Intermodulation product cancellation in communication systems |
US7313370B2 (en) | 2002-12-27 | 2007-12-25 | Nokia Siemens Networks Oy | Intermodulation product cancellation in communications |
Also Published As
Publication number | Publication date |
---|---|
EP1346473A2 (en) | 2003-09-24 |
KR20030090616A (en) | 2003-11-28 |
WO2002052718A2 (en) | 2002-07-04 |
TW525344B (en) | 2003-03-21 |
EP1346473A4 (en) | 2004-08-04 |
WO2002052717A3 (en) | 2003-04-03 |
CN1483242A (en) | 2004-03-17 |
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