US4588958A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Adjustable reflective predistortion circuit
Assignee: Lockheed Martin Corp
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Filing: 1985-03-29
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Granted: 1986-05-13
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Expires: 2005-03-29
Abstract
Abstract A predistortion circuit of the reflective type uses antiparallel-connected diodes for the desired amplitude and phase nonlinearity. If the signal applied to the diodes is of not of the correct magnitude, the desired nonlinearity will not be obtained. The magnitude of the signal applied to the diodes is increased or decreased as required by an impedance transforming circuit. The impedance transforming circuit is tuned for the frequencies of interest. The overall distortion is reduced by applying a direct bias to the diode pair.
Inventors
- 👤 Allen Katz
- 👤 Rajagopalan Sudarsanam
- 👤 Donald E. Aubert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:43
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/32; H03F1/3241; H03F1/3276; H03G; H03G7/00
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
264 words
A predistorted AC amplifier arrangement comprising: a directional coupler including first, second, third and fourth ports, said first and second ports being arranged for coupling signals therebetween with reference phase shift, said third and fourth ports being arranged for coupling signals therebetween with reference phase shift, said first and third ports being arranged for coupling signals therebetween with a phase-shift in quadrature with said reference phase shift, and said second and fourth ports being arranged for coupling signals therebetween with a phase shift in quadrature with said reference phase shift; a source of signal coupled to said first port; an amplifier coupled to said fourth port for receiving signals to be amplified, said amplifier having incremental gain which decreases at increasing signal ouput levels, whereby large-amplitude output signals experience a relative compression; a reactive network coupled to said second port, said reactive network comprising capacitive means coupled in parallel with a first end of a transmission line including a second end which is open-circuited; antiparallel-connected diodes having an input-output voltage characteristic similar to that of said amplifier but at a different impedance level; bias means for biasing said antiparallel-connected diodes with a direct current for adjusting said input-output voltage characteristic to match said incremental gain; and impedance transforming means coupled to said third port and to said antiparallel-connected diodes for coupling the impedance-transformed input-output voltage characteristic of said antiparallel-connected diodes to said third port whereby the reflected signals from said reactive network and said antiparallel-connected diodes add at said fourth port in such a fashion as to be predistorted to offset said relative compression.
Claim 2
Dependent Claim
264 words
A predistorted AC amplifier arrangement comprising: a directional coupler including first, second, third and fourth ports, said first and second ports being arranged for coupling signals therebetween with reference phase shift, said third and fourth ports being arranged for coupling signals therebetween with reference phase shift, said first and third ports being arranged for coupling signals therebetween with a phase-shift in quadrature with said reference phase shift, and said second and fourth ports being arranged for coupling signals therebetween with a phase shift in quadrature with said reference phase shift; a source of signal coupled to said first port; an amplifier coupled to said fourth port for receiving signals to be amplified, said amplifier having incremental gain which decreases at increasing signal ouput levels, whereby large-amplitude output signals experience a relative compression; a reactive network coupled to said second port, said reactive network comprising capacitive means coupled in parallel with a first end of a transmission line including a second end which is open-circuited; antiparallel-connected diodes having an input-output voltage characteristic similar to that of said amplifier but at a different impedance level; bias means for biasing said antiparallel-connected diodes with a direct current for adjusting said input-output voltage characteristic to match said incremental gain; and impedance transforming means coupled to said third port and to said antiparallel-connected diodes for coupling the impedance-transformed input-output voltage characteristic of said antiparallel-connected diodes to said third port whereby the reflected signals from said reactive network and said antiparallel-connected diodes add at said fourth port in such a fashion as to be predistorted to offset said relative compression.
Claim 3
Dependent Claim
27 words
An arrangement according to claim 1 wherein said transmission line has an impedance at said second end which is lower than the impedance at said first end.
Claim 4
Dependent Claim
32 words
An arrangement according to claim 2 wherein said impedance transforming means is tuned and comprises a length of second transmission line and capacitive means loading the center of said second transmission line.
Claim 5
Dependent Claim
27 words
An arrangement according to claim 1 wherein said impedance transforming means comprises a length of transmission line and capacitive means loading the center of said transmission line.
Claim 6
Dependent Claim
27 words
An arrangement according to claim 4 wherein said length of transmission line has a lower characteristic impedance than the input and output impedances of said directional coupler.
Claim 7
Dependent Claim
193 words
A predistortion arrangement, comprising: an amplifier exhibiting nonlinearity of its output signals at a desired output signal level, and having a gain which together with said desired output level defines a desired input signal level, and also being characterized for operation at a predetermined input and output impedance level; a circuit coupled to said amplifier for generating an input signal at said input signal level, including a two-terminal device having a nonlinear transfer characteristic, said nonlinear transfer characteristic including a first region exhibiting nonlinearity less than that of said amplifier at said desired output level, a second region exhibiting nonlinearity substantially equal to that of said amplifier at said desired output level, and a third region exhibiting nonlinearity greater than that of said amplifier of said desired output level, said nonlinear device operating in one of said first and third regions when driven from said predetermined impedance level to produce said input signal at said input signal level; and signal transforming means coupled to said device for setting the signal level across said device during operation to produce said input signal at said input signal level to establish operation in said second region.
Claim 8
Dependent Claim
193 words
A predistortion arrangement, comprising: an amplifier exhibiting nonlinearity of its output signals at a desired output signal level, and having a gain which together with said desired output level defines a desired input signal level, and also being characterized for operation at a predetermined input and output impedance level; a circuit coupled to said amplifier for generating an input signal at said input signal level, including a two-terminal device having a nonlinear transfer characteristic, said nonlinear transfer characteristic including a first region exhibiting nonlinearity less than that of said amplifier at said desired output level, a second region exhibiting nonlinearity substantially equal to that of said amplifier at said desired output level, and a third region exhibiting nonlinearity greater than that of said amplifier of said desired output level, said nonlinear device operating in one of said first and third regions when driven from said predetermined impedance level to produce said input signal at said input signal level; and signal transforming means coupled to said device for setting the signal level across said device during operation to produce said input signal at said input signal level to establish operation in said second region.
Claim 9
Dependent Claim
33 words
An arrangement according to claim 6 wherein said circuit further comprises: bias means coupled to said two-terminal device for establishing one of a direct voltage across and a direct current through said device.
Claim 10
Dependent Claim
14 words
An arrangement according to claim 6, wherein said two-terminal device comprises a first diode.
Claim 11
Dependent Claim
17 words
An arrangement according to claim 8, further comprising a second diode antiparallel coupled with said first diode.
Claim 12
Dependent Claim
75 words
An arrangement according to claim 6 wherein said circuit further comprises: a quadrature directional coupler including a signal input port and second, third and fourth ports; a substantially reactive linear termination coupled to said second port; coupling means coupled to said third port and by way of said signal transforming means to said two-terminal device; and second coupling means coupled to said fourth port and to said amplifier for coupling predistorted signals to said amplifier.
Claim 13
Dependent Claim
34 words
An arrangement according to claim 10 further comprising bias means coupled to said two-terminal device for establishing one of a direct voltage across said two-terminal device and a direct current through said two-terminal device.
Claim 14
Dependent Claim
14 words
An arrangement according to claim 11 wherein said two-terminal device comprises a first diode.
Claim 15
Dependent Claim
19 words
An arrangement according to claim 12 wherein said two-terminal device comprises a second diode antiparallel-connected with said first diode.
Claim 16
Dependent Claim
211 words
An arrangement comprising: a source of signals to be amplified; an amplifier having gain and exhibiting nonlinearity of its output signals at a desired output signal level, said gain and output signal level together determining the input signal level necessary at an input terminal; a nonlinear circuit coupled to said source of signals and to said input terminal of said amplifier for predistorting said signals from said source and for coupling predistorted signals to said input terminal of said amplifier, said nonlinear circuit including a nonlinear device having a transfer characteristic including a first region exhibiting nonlinearity less than said nonlinearity of said amplifier at said desired output signal level, a second region exhibiting nonlinearity substantially equal to said nonlinearity of said amplifier at said desired output signal level, and a third region exhibiting nonlinearity greater than said nonlinearity of said amplifier at said desired output signal level, said nonlinear device operating in said first region in response to said input signal level whereby predistortion is not adequate; and signal transforming and coupling means coupled to said source, to said input terminal of said amplifier and to said device for transforming said input signal level to a level for operating said device in said second region whereby said distortion is compensated.
Claim 17
Dependent Claim
211 words
An arrangement comprising: a source of signals to be amplified; an amplifier having gain and exhibiting nonlinearity of its output signals at a desired output signal level, said gain and output signal level together determining the input signal level necessary at an input terminal; a nonlinear circuit coupled to said source of signals and to said input terminal of said amplifier for predistorting said signals from said source and for coupling predistorted signals to said input terminal of said amplifier, said nonlinear circuit including a nonlinear device having a transfer characteristic including a first region exhibiting nonlinearity less than said nonlinearity of said amplifier at said desired output signal level, a second region exhibiting nonlinearity substantially equal to said nonlinearity of said amplifier at said desired output signal level, and a third region exhibiting nonlinearity greater than said nonlinearity of said amplifier at said desired output signal level, said nonlinear device operating in said first region in response to said input signal level whereby predistortion is not adequate; and signal transforming and coupling means coupled to said source, to said input terminal of said amplifier and to said device for transforming said input signal level to a level for operating said device in said second region whereby said distortion is compensated.
Claim 18
Dependent Claim
65 words
An arrangement according to claim 14 wherein said amplifier has a large gain whereby a relatively small input signal level is required whereby said nonlinear device would operate in said first region in the absence of an impedance transformation, and wherein said signal transforming and coupling means transforms said input level to a higher signal level for operating said nonlinear device in said second region.
Claim 19
Dependent Claim
30 words
An arrangement according to claim 15 wherein said nonlinear device comprises a diode and said higher signal level creates a greater voltage excursion across the transfer characteristic of said diode.
Claim 20
Dependent Claim
28 words
An arrangement according to claim 16 further comprising biasing means coupled to said diode for producing one of a direct voltage and a direct current through said diode.
Claim 21
Dependent Claim
17 words
An arrangement according to claim 17 further comprising a second diode antiparallel connected with said first-mentioned diode.
Claim 22
Dependent Claim
78 words
An arrangement according to claim 18 wherein said nonlinear circuit further comprises: a four-port 90° directiona coupler having a first port coupled to said source of signal to be amplified, a second port coupled to said input terminal of said amplifier, a third port coupled to said first and second diodes by way of said signal transforming and coupling means, and a fourth port; and an open-circuited transmission line having an input end coupled to said fourth port.
Claim 23
Dependent Claim
30 words
An arrangement according to claim 19 wherein said signal transforming and coupling means comprises a tuned transmission line coupled to said third port and to said first and second diodes.
Claim 24
Dependent Claim
178 words
A predistortion circuit comprising: a four port 90° directional coupler having first, second, third and fourth ports, said first port being adapted for receiving signals to be predistorted; a tapered transmission line having a first end coupled to said second port and a second end open-circuited; first voltage variable capacitance means coupled in parallel with said first end of said tapered transmission line; first control means coupled to said first voltage variable capacitance means for controlling the voltage thereacross; second transmission line means having a first end coupled to said third port and also having a second end; second voltage variable capacitance means coupled across said second transmission line means at a point along its length; second control means coupled to said second voltage variable capacitance means for controlling the voltage thereacross; first and second antiparallel connected diodes coupled across said second end of said second transmission line means; and third control means coupled to said antiparallel connected diodes for controlling the bias applied thereto, whereby predistorted signals are generated at said fourth port of said directional coupler.
Claim 25
Dependent Claim
178 words
A predistortion circuit comprising: a four port 90° directional coupler having first, second, third and fourth ports, said first port being adapted for receiving signals to be predistorted; a tapered transmission line having a first end coupled to said second port and a second end open-circuited; first voltage variable capacitance means coupled in parallel with said first end of said tapered transmission line; first control means coupled to said first voltage variable capacitance means for controlling the voltage thereacross; second transmission line means having a first end coupled to said third port and also having a second end; second voltage variable capacitance means coupled across said second transmission line means at a point along its length; second control means coupled to said second voltage variable capacitance means for controlling the voltage thereacross; first and second antiparallel connected diodes coupled across said second end of said second transmission line means; and third control means coupled to said antiparallel connected diodes for controlling the bias applied thereto, whereby predistorted signals are generated at said fourth port of said directional coupler.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-12 | 1989-11-11 | 1990-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-12 | 1993-11-11 | 1994-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-12 | 1997-11-11 | 1998-05-13 | $7700.00 | Window Closed / Lapsed |