657:
200:
648:
microseconds. A chain of many sections in tandem will be required. For television purposes, a maximum frequency of 6 MHz might be chosen, which corresponds to a delay of 83ns. Again, many sections may be required to fully equalise. In general, much greater attention is paid to the routing and exact length of television cables because many more equaliser sections are required to remove the same delay difference as compared to audio.
704:
of 0.7 ns. The device operates at a temperature of 77 K. The layout of the components corresponds to the layout shown in the circuit diagram at the head of this article, except that the relative positions of L' and C' have been interchanged so that C' can be implemented as a capacitance to ground.
566:
There is one remaining degree of freedom that the designer can use to maximally linearise the phase/frequency response. This parameter is usually stated as the L/C ratio. As stated above, it is not practical to linearise the phase response above 180°, i.e. half a cycle, so once a maximum frequency
264:
action between the two halves of L, which had been steadily becoming more significant as the frequency increased, now becomes dominant. The winding of the coil is such that the secondary winding produces an inverted voltage to the primary. That is, at resonance the phase shift is now 180°. As the
265:
frequency continues to increase, the phase delay also continues to increase and the input and output start to come back into phase as a whole cycle delay is approached. At high frequencies L and L' approach open-circuit and C approaches short-circuit and the phase delay tends to level out at 360°.
230:
The network is used when it is required that two or more signals are matched to each other on some form of timing criterion. Delay is added to all other signals so that the total delay is matched to the signal which already has the longest delay. In television broadcasting, for instance, it is
231:
desirable that the timing of the television waveform synchronisation pulses from different sources are aligned as they reach studio control rooms or network switching centres. This ensures that cuts between sources do not result in disruption at the receivers. Another application occurs when
647:
For broadcast sound purposes, 15 kHz is often chosen as the maximum usable frequency on landlines. A delay equaliser designed to this specification can, therefore, insert a delay of 33μs. In reality, the differential delay that might be required to equalise may be many hundreds of
255:
the network introduces. At low frequencies L is low impedance and C' is high impedance and consequently the signal passes through the network with no shift in phase. As the frequency increases, the phase shift gradually increases, until at some frequency,
561:
319:
is constant at all frequencies over the band of operation. φ must, therefore, be kept linearly proportional to ω. With a suitable choice of parameters, the network phase shift can be made linear up to about 180° phase shift.
705:
One plate of this capacitor is the ground plane and it thus has a much simpler pattern (a simple rectangle) than the pattern of C which needs to be a series capacitor in the main transmission line.
323:
The network is terminated in a characteristic impedance (not shown in the circuit diagram), ideally a resistance R, which is the input impedance to the successive circuit or transmission line.
642:
398:
310:
439:
186:
243:. When the landlines are long and the two channels arrive by substantially different routes it can require many filter sections to fully equalise the delay.
484:. A third parameter is set by choosing a resonant frequency, this is set to (at least) the maximum frequency the network is required to operate at.
490:
179:
332:
172:
239:
to the studio centre. It is important that delay is equalised between the two stereo channels as a difference will destroy the
260:, the shunt branch of the circuit, L'C', goes in to resonance and causes the centre-tap of L to be short-circuited to ground.
215:
347:
of each other (ignoring the transformer action) which provides two parameters for calculating component values. These are
852:
673:
580:
837:
724:
672:
Losses in the circuit cause the maximum delay to be reduced, a problem that can be ameliorated with the use of
218:
whose purpose is to insert an (ideally) constant delay at all frequencies in the signal path. It is a class of
816:
801:
779:
770:
H. J. Chaloupka, S. Kolesov, "Design of lumped-element 2D RF devices", H. Weinstock, Martin
Nisenoff (eds),
353:
97:
278:
689:
847:
67:
62:
30:
842:
832:
719:
445:
108:
574:
is chosen, this sets the maximum delay that can be designed in to the circuit and is given by,
403:
120:
80:
792:
Jay C. Adrick, "Analog television transmitters", in, Edmund A. Williams (editor-in-chief),
677:
8:
693:
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232:
125:
37:
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775:
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19:
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42:
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714:
336:
211:
57:
47:
344:
240:
556:{\displaystyle \omega _{0}={\frac {1}{\sqrt {4LC}}}={\frac {1}{\sqrt {L'C'}}}}
826:
729:
700:
band and has a centre frequency of approximately 2.8 GHz and achieves a peak
340:
102:
52:
807:
Phillip R. Geffe, "LC filter design", in, John Taylor, Qiuting Huang (eds),
199:
219:
701:
261:
252:
158:
685:
460:
153:
148:
143:
697:
681:
456:
272:) with angular frequency (ω) is given by the simple relation,
661:
796:, 10th edition, pp. 1483-1484, Taylor & Francis, 2013
268:
The relationship between phase shift (φ) and time delay (T
794:
National
Association of Broadcasters Engineering Handbook
651:
331:
The four component values of the network provide four
660:
2.8 GHz superconducting bridged T delay equaliser in
583:
493:
406:
356:
281:
343:) that the L/C branch and the L'/C' branch are the
636:
555:
433:
392:
304:
824:
251:The operation is best explained in terms of the
688:technology. The traces are the superconductor
235:is connected by landline, for instance from an
637:{\displaystyle T_{D(max)}={\frac {1}{2f_{m}}}}
180:
187:
173:
676:. Such a circuit has been realised as a
301:
655:
198:
825:
393:{\displaystyle C'={\frac {4L}{R^{2}}}}
786:
652:Superconductor planar implementation
335:in the design. It is required from
305:{\displaystyle \phi =\omega T_{D}\,}
764:
13:
809:CRC Handbook of Electrical Filters
470:in the right half-plane such that
14:
864:
696:. The circuit is for use in the
444:Equivalently, every transmission
674:high-temperature superconductors
757:Chaloupka & Kolesov, p. 234
748:Chaloupka & Kolesov, p. 233
225:
751:
742:
604:
592:
1:
811:, pp. 76-77, CRC Press, 1997
735:
63:Optimum "L" (Legendre) filter
725:Bartlett's bisection theorem
246:
7:
772:Microwave Superconductivity
708:
690:yttrium barium copper oxide
463:must have a matching zero,
10:
869:
853:Electronic filter topology
680:planar implementation in
434:{\displaystyle L'=CR^{2}}
326:
208:bridged-T delay equaliser
115:Bridged T delay equaliser
31:Network synthesis filters
838:Image impedance filters
720:Lattice phase equaliser
81:Image impedance filters
48:Elliptic (Cauer) filter
669:
638:
557:
435:
394:
306:
203:
121:Composite image filter
692:and the substrate is
659:
639:
558:
436:
395:
315:It is required that T
307:
202:
98:General image filters
68:Linkwitz–Riley filter
581:
491:
404:
354:
279:
694:lanthanum aluminate
666:lanthanum aluminate
105:(constant R) filter
787:General references
670:
634:
553:
431:
390:
333:degrees of freedom
302:
233:stereophonic sound
216:bridged-T topology
214:circuit utilising
204:
38:Butterworth filter
22:electronic filters
848:Electronic design
774:, Springer, 2012
632:
551:
550:
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237:outside broadcast
210:is an electrical
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88:Constant k filter
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765:Cited references
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93:m-derived filter
43:Chebyshev filter
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843:Analog circuits
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715:All-pass filter
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126:mm'-type filter
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58:Gaussian filter
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833:Linear filters
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678:lumped-element
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567:of operation,
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138:Simple filters
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109:Lattice filter
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730:Zobel network
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53:Bessel filter
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20:Linear analog
18:
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808:
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771:
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671:
646:
568:
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449:
443:
337:image theory
330:
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314:
267:
250:
241:stereo image
229:
226:Applications
220:image filter
207:
205:
114:
702:group delay
262:Transformer
253:phase shift
827:Categories
817:0849389518
802:1136034102
780:9401004501
736:References
686:microstrip
461:half-plane
159:RLC filter
117:(all-pass)
111:(all-pass)
698:microwave
682:thin-film
668:substrate
496:ω
289:ω
283:ϕ
247:Operation
154:LC filter
149:RL filter
144:RC filter
709:See also
547:′
539:′
457:s-domain
412:′
362:′
455:in the
815:
800:
778:
684:using
327:Design
459:left
339:(see
813:ISBN
798:ISBN
776:ISBN
662:YBCO
446:pole
400:and
345:dual
206:The
664:on
829::
477:=−
448:,
222:.
819:.
804:.
782:.
627:m
623:f
619:2
615:1
610:=
605:)
602:x
599:a
596:m
593:(
590:D
586:T
572:m
569:f
544:C
536:L
531:1
526:=
520:C
517:L
514:4
510:1
505:=
500:0
482:z
479:s
475:p
472:s
468:z
465:s
453:p
450:s
427:2
423:R
419:C
416:=
409:L
384:2
380:R
375:L
372:4
366:=
359:C
317:D
297:D
293:T
286:=
270:D
258:0
256:ω
188:e
181:t
174:v
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