CN100463374C

CN100463374C - Improved circuit of 1394b signal transmission line

Info

Publication number: CN100463374C
Application number: CNB2004100918791A
Authority: CN
Inventors: 许寿国
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Current assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Priority date: 2004-12-25
Filing date: 2004-12-25
Publication date: 2009-02-18
Anticipated expiration: 2024-12-25
Also published as: CN1794571A

Abstract

This invention provides an improved circuit of 1394b signal transmission line including a 1394b signal transmission drive circuit, a load circuit, a first signal line, a second signal line and a 1394b interface characterizing in including a first impedance, a second impedance and a third impedance, in which, the second impedance is serial between the interface and the first signal line, the third impedance is serial between the interface and the second signal line, one end of the first impedance is connected between the first signal line and the second impedance and the other end is between the second signal line and the third impedance.

Description

The improvement circuit of 1394b signal transmssion line

[technical field]

The invention relates to a kind of improvement circuit of 1394b signal transmssion line, particularly a kind of when its impedance does not reach requirements, it is carried out impedance-compensated circuit.

[background technology]

1394b is the up-to-date upgraded version of 1394 (Fire Wire) technology, is the household network standards that designs at multimedia video, audio frequency, control and computer specially.It realizes the high-performance home network by low-cost, safe CAT5 (five classes).The 1394b signal transmssion line is the downward compatibility expansion of 1394a technology.This novel revised edition can provide higher performance (up to 3200Mbps), longer distance (reaching 100 meters) and various wired media, to adapt to various application, as POF (plastic fiber), GOF (glass fibre), STP (Shielded Twisted Pair), UTP (unshielded twisted pair).For home network, 1394b signal transmssion line speed on the CAT5 of 100m cable can reach 100Mbps.

The thickness of general pcb board is thin more, its signal and performance are good more, there is the bus generation noise that runs up in the PCB of for example former use solid pressure sheet 2116, time of delay (Flight time) and rise time (Rise time) are longer, effect is undesirable, but if uses solid pressure sheet 1080 that the problems referred to above are improved.Because of the thickness of solid pressure sheet 2116 greater than 1080 thickness, so can reduce the thickness of whole PCB, the minimizing of PCB thickness can effectively reduce the noise of crosstalking of the bus that runs up, and use the folded structure of above-mentioned kind that live width and line-spacing are reduced, the impedance of lead and dielectric constant also with minimizing, thereby shorten time of delay (Flight time) and rise time (Rise time) and can obtain bigger wiring space (Routing room).But after being to use solid pressure sheet 1080, the line widths shrink of PCB, its respective impedance reduces thereupon, and then its total resistance value also diminishes, and does not reach the desired impedance of 1394b signal transmssion line.

See also Fig. 1, it is known 1394b signal transmssion line circuit.Foregoing circuit comprises a 1394b signal transmssion line drive circuit 101, a load circuit 102, one first holding wire 103, a secondary signal line 104 and a 1394b interface 105.After using solid pressure sheet 1080 its live width and/line-spacing becomes 4/10 (mil) by 5/15 (mil) of use solid pressure sheet 2116, then the resistance value at 1394b interface 105 places is the also minimizing thereupon of resistance value between contact a and the contact b, become present 100 ohm (values approximately) by original 108.5 ohm, and the desired impedance of 1394b signal transmssion line is 110+/-6 ohm, therefore cause that overshoot (overshoot) exceeds that the 1394b signal transmssion line allowed 10%, so how present problem to be solved for can use solid pressure sheet 1080 can make its impedance and overshoot value meet the demand of 1394b signal transmssion line again.

[summary of the invention]

The object of the present invention is to provide a kind of improvement circuit of 1394b signal transmssion line, particularly when its impedance not being reached require impedance, make improvements to reach the circuit of the required normal impedance value of 1394b.

The objective of the invention is to realize by following scheme: the present invention is a kind of improvement circuit of 1394b signal transmssion line, it comprises a 1394b signal transmssion line drive circuit, one load circuit, one first holding wire, one secondary signal line, one 1394b interface, comprise one first impedance in addition, one second impedance and one the 3rd impedance, wherein, second impedance is series between the above-mentioned 1394b interface and first holding wire, the 3rd impedance is series between 1394b interface and the secondary signal line, first impedance, one end is connected between first holding wire and second impedance, and the other end is connected between secondary signal line and the 3rd impedance.

The invention has the advantages that: when improving the PCB performance, also can make its resistance value reach requirements.

[description of drawings]

Fig. 1 is known 1394b signal transmssion line circuit diagram.

Fig. 2 improves the circuit diagram of circuit for 1394b signal transmssion line of the present invention.

Fig. 3 improves the equivalent circuit diagram of circuit for 1394b signal transmssion line of the present invention.

Fig. 4 improves another equivalent circuit diagram of circuit for 1394b signal transmssion line of the present invention.

Simulation result figure before Fig. 5 improves the back and improves for 1394b signal transmssion line of the present invention improves circuit.

[embodiment]

See also Fig. 2, it is the circuit diagram that 1394b signal transmssion line of the present invention improves circuit.Foregoing circuit comprises a 1394b signal transmssion line drive circuit 101, one load circuit 102, one first holding wire 103, an one secondary signal line 104 and a 1394b interface 105, comprise one first impedance R1 in addition, one second impedance R2 and one the 3rd impedance R3, wherein, the second impedance R2 is series between the above-mentioned 1394b interface 105 and first holding wire 103, the 3rd impedance R3 is series between 1394b interface 105 and the secondary signal line 104, the first impedance R1, one end is connected between first holding wire 103 and the second impedance R2, and the other end is connected between secondary signal line 104 and the 3rd impedance R3.The purpose that increases above-mentioned three impedances is to make that 1394b interface 105 places are that the impedance at contact c and contact d two ends becomes desired 110 ohm, below can according to the equation of equivalent circuit diagram gained try to achieve the first impedance R1, the second impedance R2 and the 3rd impedance R3 corresponding concrete resistance value;

See also Fig. 3, it is the equivalent circuit diagram that 1394b signal transmssion line of the present invention improves circuit.We can be resistance value equivalence between contact a and the contact b known impedance Rab at this, with the equivalent resistance of R2 and R3 is an equivalent impedance R4, then can get its annexation: the Rab and first resistance R 1 and connect with equivalent resistance R4 again after in parallel, can get equation 1:Rcd=Rab*R1/ (Rab+R1)+R4 according to the connection in series-parallel law of closed circuit impedance;

See also Fig. 4, it is another equivalent circuit diagram that 1394b signal transmssion line of the present invention improves circuit.At this can be known impedance Rcd with the equivalence of the resistance value between contact c and the contact d, it is in parallel with R1 again after Rcd connects with equiva lent impedance R4 then can getting its annexation, in like manner the connection in series-parallel law according to the closed circuit impedance can get equation 2:Rab=(Rcd+R4) * R1/ (Rcd+R4+R1), equation 1 and equation 2 simultaneous can be got R1=Rab*Sqrt (Rcd/ (Rcd-Rab)), R4=Sqrt (Rcd-Rab) * Rcd).Bring Rab=100 into, Rcd=110 can try to achieve R1=332 ohm; R4=33 ohm, then R2=R3=R4/2=16.5 ohm.

See also Fig. 5, its be 1394b signal transmssion line of the present invention improve after the improvement of circuit with improve before simulation result figure.Wherein Y-axis is represented the voltage of 1394b signal transmssion line, X-axis is a time shaft, waveform 501 does not improve preceding simulation curve for circuit, waveform 502 is the simulation curve of circuit after improving, the normal place of horizontal line 503 standard compliant simulation curve peak values, by finding out among this figure that overshoot value after circuit improves less than the overshoot value before improving, reaches the demand of 1394b signal transmssion line.

Claims

1. the improvement circuit of a 1394b signal transmssion line, foregoing circuit comprises a 1394b signal transmssion line drive circuit, one load circuit, one first holding wire, one secondary signal line, one 1394b interface, it is characterized in that: the improvement circuit of above-mentioned 1394b signal transmssion line also comprises one first impedance, one second impedance and one the 3rd impedance, wherein, above-mentioned second impedance is series between above-mentioned 1394b interface and above-mentioned first holding wire, above-mentioned the 3rd impedance is series between above-mentioned 1394b interface and the above-mentioned secondary signal line, above-mentioned first impedance, one end is connected between above-mentioned first holding wire and above-mentioned second impedance, and the other end is connected between above-mentioned secondary signal line and above-mentioned the 3rd impedance.

2. the improvement circuit of 1394b signal transmssion line as claimed in claim 1, it is characterized in that, be provided with a contact a between first holding wire and second impedance, be provided with a contact b between secondary signal line and the 3rd impedance, the impedance between contact a and the contact b is equating with the resistance value of 1394b interface with resistance value that above-mentioned first impedance, second impedance and the 3rd impedance connect the back gained.

3. as the improvement circuit of 1394b signal transmssion line as described in the claim 2, it is characterized in that, resistance value between contact a and the contact b is Rab, the resistance value of 1394b interface is Rcd, the resistance value of first impedance is R1, the resistance value of second impedance is R2, and the resistance value of the 3rd impedance is R3, then can get equation according to the annexation of the improvement circuit of above-mentioned 1394b signal transmssion line and the connection in series-parallel law of closed circuit:

Rab=(Rcd+R2+R3) * R1/ (Rcd+R2+R3+R1) reaches

Rcd＝Rab*R1/(Rab+R1)+R2+R3。

4. as the improvement circuit of 1394b signal transmssion line as described in the claim 3, it is characterized in that the improvement circuit of above-mentioned 1394b signal transmssion line is a difference channel, then can get: R2=R3, bring given value Rab and Rcd into above-mentioned equation, can get:

R1＝Rab*Sqrt(Rcd/(Rcd-Rab))；

R2＝R3＝Sqrt(Rcd-Rab)*Rcd/2。