Patent US4717896A successfully refreshed from Google Patents.
US4717896A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Balun
Assignee: AND YET INC 3060 BUENA VISTA WAY BERKELEY 94708
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Filing: 1985-03-21
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Granted: 1988-01-05
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Expires: 2005-03-21
Abstract
Abstract The present invention comprises a balun for intercoupling an at least partially unbalanced line and a substantially balanced line having similar line impedances which is capable of passing differential signals over a wide bandwidth while substantially attenuating any common mode signals. The balun comprises a pair of transformers with bifilar windings, each connected as a choke. Each conductor of the unbalanced line is coupled to a different one of two substantially identical inductances of the first transformer and the other side of each inductance is coupled through the second transformer to a different one of the two conductors of the balanced line. Each of the connections between the two transformers is coupled to ground with a substantially identical capacitance. The capacitance in conjunction with the inductance acts to filter out the common mode signals while allowing the differential mode signals to pass through the balun. The capacitance is coupled to each transmission line by a transformer with sufficient inductance to prevent differential signals in either direction from being shunted to ground. Preferably, a resistor is added in parallel to each of the capacitances to provide for common mode attenuation at the resonant frequency of the system capacitance and inductances.
Inventors
- 👤 Martin H. Graham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:16
CPC Classifications
H; H03; H03H; H03H7/00; H03H7/42
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
313 words
A balun for coupling a signal of a predetermined bandwidth between an at least partially unbalanced two-conductor line having a first and a second conductor and a balanced two-conductor line having a first and second conductor, comprising: a first inductance adapted to have a first lead coupled to the first conductor of said unbalanced line; a second inductance adapted to have a first lead coupled to the second conductor of said unbalanced line, said second inductance sharing a common core with said first inductance and having a substantially equal value to said first inductance; a third inductance having a first lead coupled to a second lead of said first inductance and adapted to have a second lead coupled to a first conductor of said balanced line; a fourth inductance having a first lead coupled to a second lead of said second inductance and adapted to have a second lead coupled to a second conductor of said balanced line, said fourth inductance sharing a common core with said third inductance and having a substantially equal value to said third inductance; a first capacitance coupling said second lead of said first inductance to ground; a second capacitance coupling said second lead of said second inductance to ground, said second capacitance being substantially equal in value to said first capacitance; a first resistance coupled in parallel with said first capacitance; and a second resistance coupled in parallel with said second capacitance, said second resistance being substantially equal in value to said first resistance; the combined parallel impedance of said first and second resistances and said first and second capacitance being lower than the open circuit impedance of said first and second inductances, and said third and fourth inductances over said predetermined bandwidth, and the series impedance of said first resistance and capacitance, and said second resistance and capacitance being higher than the impedance of said lines.
Claim 2
Dependent Claim
313 words
A balun for coupling a signal of a predetermined bandwidth between an at least partially unbalanced two-conductor line having a first and a second conductor and a balanced two-conductor line having a first and second conductor, comprising: a first inductance adapted to have a first lead coupled to the first conductor of said unbalanced line; a second inductance adapted to have a first lead coupled to the second conductor of said unbalanced line, said second inductance sharing a common core with said first inductance and having a substantially equal value to said first inductance; a third inductance having a first lead coupled to a second lead of said first inductance and adapted to have a second lead coupled to a first conductor of said balanced line; a fourth inductance having a first lead coupled to a second lead of said second inductance and adapted to have a second lead coupled to a second conductor of said balanced line, said fourth inductance sharing a common core with said third inductance and having a substantially equal value to said third inductance; a first capacitance coupling said second lead of said first inductance to ground; a second capacitance coupling said second lead of said second inductance to ground, said second capacitance being substantially equal in value to said first capacitance; a first resistance coupled in parallel with said first capacitance; and a second resistance coupled in parallel with said second capacitance, said second resistance being substantially equal in value to said first resistance; the combined parallel impedance of said first and second resistances and said first and second capacitance being lower than the open circuit impedance of said first and second inductances, and said third and fourth inductances over said predetermined bandwidth, and the series impedance of said first resistance and capacitance, and said second resistance and capacitance being higher than the impedance of said lines.
Claim 3
Dependent Claim
442 words
A balun for coupling a plurality of at least partially unbalanced two-conductor lines to a plurality of balanced two-conductor lines, each partially unbalanced two-conductor line having a first and a second conductor and each corresponding balanced two-conductor line having a first and second conductor, comprising: a first inductance adapted to have a first lead coupled to the first conductor of a first one of said unbalanced lines; a second inductance adapted to have a first lead coupled to the second conductor of said first one of said unbalanced lines and to a second conductor of a second unbalanced line, said seciond inductance sharing a common core with said first inductance and having a substantially equal value to said first inductance; a third inductance adapted to have a first lead coupled to the first conductor of said second unbalanced line, said third inductance sharing a common core with said first and second inductances and having a substantially equal value to said first inductance; a fourth inductance coupled at a first lead to a second lead of said first inductance and adapted to have a second lead coupled to a first conductor of a first one of said balanced lines; a fifth inductance having a first lead coupled to a second lead of said second inductance and adapted to have a second lead coupled to a second conductor of said corresponding first balanced line and to a second conductor of a corresponding second one of said balanced lines, said fifth inductance sharing a common core with said fourth inductance and having a substantially equal value to said fourth inductance; a sixth inductance having a first lead coupled to a second lead of said third inductance and adapted to have a second lead coupled to a first conductor of said corresponding second balanced line, said sixth inductance sharing a common core with said fourth and fifth inductances and having a substantially equal value to said fourth inductance; a first capacitance coupling said second lead of said first inductance to ground; a second capacitance coupling said second lead of said second inductance to ground, said second capacitance being substantially equal in value to said first capacitance; a third capacitance coupling said second lead of said third inductance to ground, said third capacitance being substantially equal in value to said first capacitance; a first resistance coupled in parallel with said first capacitance; a second resistance coupled in parallel with said second capacitance, said second resistance being substantially equal in value to said first resistance; and a third resistance coupled in parallel with said third capacitance, said third resistance being substantially equal in value to said first resistance.
Claim 4
Dependent Claim
442 words
A balun for coupling a plurality of at least partially unbalanced two-conductor lines to a plurality of balanced two-conductor lines, each partially unbalanced two-conductor line having a first and a second conductor and each corresponding balanced two-conductor line having a first and second conductor, comprising: a first inductance adapted to have a first lead coupled to the first conductor of a first one of said unbalanced lines; a second inductance adapted to have a first lead coupled to the second conductor of said first one of said unbalanced lines and to a second conductor of a second unbalanced line, said seciond inductance sharing a common core with said first inductance and having a substantially equal value to said first inductance; a third inductance adapted to have a first lead coupled to the first conductor of said second unbalanced line, said third inductance sharing a common core with said first and second inductances and having a substantially equal value to said first inductance; a fourth inductance coupled at a first lead to a second lead of said first inductance and adapted to have a second lead coupled to a first conductor of a first one of said balanced lines; a fifth inductance having a first lead coupled to a second lead of said second inductance and adapted to have a second lead coupled to a second conductor of said corresponding first balanced line and to a second conductor of a corresponding second one of said balanced lines, said fifth inductance sharing a common core with said fourth inductance and having a substantially equal value to said fourth inductance; a sixth inductance having a first lead coupled to a second lead of said third inductance and adapted to have a second lead coupled to a first conductor of said corresponding second balanced line, said sixth inductance sharing a common core with said fourth and fifth inductances and having a substantially equal value to said fourth inductance; a first capacitance coupling said second lead of said first inductance to ground; a second capacitance coupling said second lead of said second inductance to ground, said second capacitance being substantially equal in value to said first capacitance; a third capacitance coupling said second lead of said third inductance to ground, said third capacitance being substantially equal in value to said first capacitance; a first resistance coupled in parallel with said first capacitance; a second resistance coupled in parallel with said second capacitance, said second resistance being substantially equal in value to said first resistance; and a third resistance coupled in parallel with said third capacitance, said third resistance being substantially equal in value to said first resistance.
References Cited (Backward Citations)
US1759332A
Cited
US1866525A
Cited
US2084740A
Cited
US2172923A
Cited
US2238260A
Cited
US2272701A
Cited
US2272731A
Cited
US2412609A
Cited
US2727149A
Cited
US2934721A
Cited
US3114120A
Cited
US3195076A
Cited
US3305800A
Cited
US3357023A
Cited
US3594672A
Cited
US3611233A
Cited
US3629759A
Cited
US3609613A
Cited
US3717808A
Cited
US3716806A
Cited
US3766499A
Cited
US3778759A
Cited
US3783415A
Cited
US3882432A
Cited
US4428018A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-01-04 | 1991-07-06 | 1992-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-04 | 1995-07-06 | 1996-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-04 | 1999-07-06 | 2000-01-05 | $7700.00 | Window Closed / Lapsed |