CN101588412A - Transmission duplex interface circuit suitable for compound impedance medium - Google Patents

Abstract

The invention discloses a transmission duplex interface circuit suitable for a compound impedance medium, comprising an output power amplifier (1), an impedance matching network module, a balance network module, a cancellation network module, an output interface circuit and an input power amplifier (6). The transmission duplex interface circuit suitable for the compound impedance medium is characterized in that the impedance matching network module comprises a transformer, and the cancellation network module comprises two butted transformers. The transmission duplex interface circuit is particularly suitable for application to transmission media with extremely complicated load impedance characteristics and variance, can realize cancellation in a wideband range and overcomes the defects of a bridge-type anti-sidetone technology.

Description

A kind of transmission duplex interface circuit of suitable compound impedance medium

Technical field

The present invention relates to a kind of interface circuit, especially relate to a kind of transmission duplex interface circuit of suitable compound impedance medium.

Background technology

The mesolow power-line carrier communication is by the electric power networks of power supply, carry out transfer of data with power cable or overhead transmission line resource, owing to be that what to utilize that power line carries out that transfer of data adopts is a kind of shared media (power line) communication technology, its communication mode usually adopts time-division or frequency division mode of operation, power signal sends to media (power line), receiving the far-end carrier signal from media (power line) all is same interface circuit, communicator is in order to send to high-power carrier signal on the power line, and need fall to the signal suppressing of this machine receiving terminal sending the high-power signal string, usually need to adopt the transmitting-receiving cancellation techniques, make the high-power carrier signal that sends can not produce and disturb or burn out receiving circuit receiving circuit.

Transmission duplex interface circuit is common circuit in telephone set, wireless transceiver, and at telephone-switching network, transmission duplex interface circuit adopts bridge-type anti-sidetone interface circuit, by a balancing network, reduces the sidetone that produces when sending words in own receiver.The impedance matching that bridge-type anti-sidetone Technology Need is good, yet, in power line communication, line impedance changes, and particularly in very wide range of frequency bandwidths, is difficult to accomplish impedance matching, therefore, bridge-type anti-sidetone technology can't be promoted the use of in power line communication apparatus.

Summary of the invention

1, goal of the invention

The present invention is directed to the deficiencies in the prior art, propose a kind of transmission duplex interface circuit of suitable compound impedance medium, to adapt to shared media (as the power line carrier signal) duplex communication function.Also can understand the realization technology that the present invention proposes, also the duplex communication of the impedance matching network interface of the communicator of suitable " two wires " shared medium.

2, technical scheme

Circuit disclosed in this invention comprises that 3, one of 2, one balancing networks of 1, one impedance matching network of 1 output amplifier offset 5, one input amplifiers 6 of 4, one output interface circuits of network.The output impedance of output amplifier 1 is generally very little, by impedance matching network 2, realizes impedance conversion; The function of balancing network 3 is by offseting network 4, to produce suitable " offset " voltage for offseting network 3 for this machine power output signal; Otherwise,, produce suitable " reinforcement " voltage for offseting network 3 for the received signal that comes from output interface circuit 5; The function that offsets network 4 realizes the voltage signal of balancing network output " offseting " voltage signal and output interface circuit 5 feedbacks to offset, to output to the signal of an input amplifier 6 as far as possible little by offseting network 4 for this machine of making power output signal, and signal attenuation reaches more than the 20dB; Otherwise for the received signal that comes from output interface circuit 5, by offseting network 3, signal attenuation is very little.

Power amplifier 1 signal outputs to impedance matching network 2, and to offseting network 4, the one road to output interface circuit 5, sends signal to (load impedance) on the circuit through balancing network 3, a road.Output interface circuit 5 one tunnel outputs on the circuit, and one the tunnel feeds back to and offsets network 4, and the power output signal is through after offseting network 4 and offseting, and the power output residue signal is delivered to input amplifier 6.The power signal of power amplifier 1 output outputs on the circuit through output interface circuit 5, the signal 3～5dB that generally decays; And by offseting the signal of network 2 to input interface circuit 4, offset the back decay and reach more than the 30dB.Conversely, the signal that comes from far-end is through output interface circuit 5, the signal that is input to the input interface circuit 4 that the passes through 3～5dB that only decays.

Wherein, impedance matching network is made of an impedance conversion transformer and offsets network and be made of the butt joint of two transformers.

To be balanced network module be made of the source electrode coil of a transformer the further scheme of the present invention.

Circuit has three functions: 1) output signal is through balancing network 3, and its power attenuation is as far as possible little, makes that the signal power that outputs in the load is big as far as possible; 2) output signal realizes offseting of this machine power output signal through balancing network 3 with offset network 4, makes that the power signal of this machine of arrival input is very little, reaches the effect of protection input circuit; 3) come from the received signal of output interface circuit 5, by offseting network 3, its signal attenuation is very little, guarantees the big as far as possible of received signal.

3, beneficial effect

It is that load impedance characteristic is very complicated that the present invention is particularly suitable for, and the transmission medium that changes, as the application on the power line carrier communication, variation for load impedance influences less to the result who offsets, its main feature is to realize offseting in broad frequency range, has overcome the deficiency of bridge-type anti-sidetone technology.

Description of drawings

Fig. 1 is a circuit function schematic diagram of the present invention;

Fig. 2 is the schematic diagram of the embodiment of the invention one;

Fig. 3 is the schematic diagram of the embodiment of the invention two;

Fig. 4 is the circuit theory diagrams of the embodiment of the invention two.

Embodiment

Embodiment one

As shown in Figure 2, one of concrete case that a kind of transmission duplex interface circuit of suitable compound impedance medium is implemented, it is characterized in that: this transmission duplex interface circuit is made up of three transformers, impedance matching network is made of an impedance conversion transformer 7 (n1:n2), balancing network 11 is made of an impedance (75 ohm), offsets network and is made of transformer 8 (n3:n4) and transformer 10 (n5:n6) butt joint.The power signal of output amplifier 1 connects impedance conversion transformer 7 (n1:n2) source class, and 7 levels one tunnel of impedance transformer connect the source class of transformer 8, and the no-load voltage ratio of transformer 8 is 1: 1.Another road of 7 levels of impedance transformer connects the source class and the output interface circuit 12 of transformer 10 by balancing network 11, and the no-load voltage ratio of transformer 10 is 2: 1.The secondary of secondary and transformer 10 of transformer 8 docked.

According to the present invention, offset network for the decay more than this acc power signal generation 30dB, and, only produce the additional attenuation about 3dB coming from the received signal of far-end.It realizes that principle is as follows:

The power signal of output amplifier 1 send impedance transformer 7,7 levels one tunnel of impedance transformer are sent the source class of the transformer 8 that offsets network, another road is by the source class of balancing network 11 to transformer 10, transformer 8 and 10 secondary with connecting, in theory, about 75 ohm of output load impedance, therefore, the power signal level reduces half by the source class of balancing network 11 (impedance is 75 ohm) to transformer 10, and boosting to increase through transformer 10 again is twice.In offseting network, the secondary of transformer 8 and 10 transformers connects together, after the serial connection, two transformers transform to secondary voltage level and equate, polarity is the side mutually, thereby realizes the counteracting fully of this acc power signal level, makes that the input end signal of delivering to input amplifier 9 is zero.

Yet, when specifically implementing,, can not be 75 ohm because the impedance operator of media (for example power line) is very complicated, therefore, deliver to the power signal level of input amplifier input after this acc power signal cancellation and can not offset fully.On the other hand, in this transmission duplex interface circuit, because balancing network 11 is made of a resistance (75 ohm), the power output signal has been decayed half by behind the balancing network 11.

Implement two:

As shown in Figure 3, two of the concrete case study on implementation that a kind of transmission duplex interface circuit of suitable compound impedance medium is implemented, it is characterized in that: this transmission duplex interface circuit is made up of three transformers, impedance matching network is made of an impedance conversion transformer 14 (n1:n2), balancing network 15 is made of transformer 15 (n3:n4) source class coil, offsets network and is made of transformer 15 (n3:n4) and the secondary butt joint of transformer 16 (n5:n6).The power signal of output amplifier 13 connects impedance transformer 14 (n1:n2) source class, 14 levels one tunnel of impedance transformer connect the source class of transformer 8, another road connects the source class and the output interface circuit 18 of transformer 16 by the source class coil of transformer 15, the secondary of secondary and transformer 16 of transformer 15 docked, and realizes offseting of this acc power signal.

According to the present invention, the power output signal has only decayed 1/10th by behind the balancing network 15 in theory, makes that the power signal that outputs in the load is 9/10ths.Because balancing network 15 uses transformer, overcome the problem that adopts resistance to cause heating, on the other hand, offset network for the decay more than this acc power signal generation 30dB, and, only produce the additional attenuation about 3dB coming from the received signal of far-end.Its concrete enforcement principle is as follows:

The power signal of output amplifier 13 send impedance conversion transformer 14,14 levels one tunnel of impedance conversion transformer are sent the source class of the transformer 15 that offsets network, be connected to the source class of transformer 16 by transformer 15 source class coils, transformer 16 secondary coils oppositely dock with end with the secondary of transformer 16, constitute to offset network.The no-load voltage ratio of transformer 15 is 1: 10, and transformer 16 no-load voltage ratios are 2: 1.The power signal level is by the source class of balancing network 15 to transformer 16, and decay 1/10th makes the power signal level that arrives the output interface end reach 90%.The design principle of case of the present invention is as follows:

Fig. 4 is the circuit theory diagrams of the embodiment of the invention two, according to Fig. 4, is the fundamental analysis key points in design with three functions of the present invention.1) output signal is through balancing network 3, and its power attenuation is as far as possible little, makes that the signal power that outputs in the load is big as far as possible; 2) output signal is through balancing network 3 with offset network 4, realizes that this machine power output signal to the offseting of input circuit, makes that the power signal of this machine of arrival input is very little, reaches the input circuit effect of protecting; 3) come from the received signal of output interface circuit 5, by offseting network 3, its signal attenuation is very little, guarantees the big as far as possible of received signal.

According to three functions of the present invention 1) and 2), the input signal of circuit of the present invention is power output signal U ₀, M ₁And M ₂Represent the mutual inductive impedance of transformer 15 and 16 respectively, Z ₁₁And Z ₁₂Represent the impedance of transformer 15 source class and secondary coil respectively, Z ₂₁And Z ₂₂Represent the impedance of transformer 16 source class and secondary coil respectively, set up electric current and voltage equation (1) and (2) of circuit of the present invention, separate this equation and get:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="A2008100249680010H2.png"\; state="\{\{state\}\}">U</figure-callout>}}_0=({\mathrm{<figure-callout\; id="11"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{11}+Z_{21})I_2+(M_2-M_1)I_2---\left(1\right)\\ ({\mathrm{<figure-callout\; id="12"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{12}+Z_{22})I_2+(M_2-M_1)I_1=0---\left(2\right)\end{array}\right.$

${\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A2008100249680010H2.png"\; state="\{\{state\}\}">M</figure-callout>}}_1={\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A2008100249680009H1.png,A2008100249680010H2.png"\; state="\{\{state\}\}">M</figure-callout>}}_2=\mathrm{j\&omega;k}\sqrt{L_{11}{\mathrm{<figure-callout\; id="12"\; label="L"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">L</figure-callout>}}_{12}}=\mathrm{j\&omega;k}\sqrt{L_{21}{L}_{22}}---\left(3\right)$

Z ₁₁＝R ₁₁+jωL ₁₁；Z ₁₂＝R ₁₂+jωL ₁₂；Z ₂₁＝R ₂₁+jωL ₂₁；Z ₂₂＝R ₂₂+jωL ₂₂ (4)

From formula (5) and (6) result, I ₂Be the electric current that flow in the input circuit, realize this machine power output signal if desired, must make I to the offseting of input circuit ₂Be 0 or as far as possible little, from formula (5)

$I_2=\frac{(M_2-M_1)U_0}{({\mathrm{<figure-callout\; id="11"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{11}+Z_{21})({\mathrm{<figure-callout\; id="12"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{12}+Z_{22})-{(M_2-M_1)}^2}---\left(5\right)$

$U_2=\frac{U_0{Z}_{21}}{({\mathrm{<figure-callout\; id="11"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{11}+Z_{21})-\frac{{(M_2-M_1)}^2}{({\mathrm{<figure-callout\; id="12"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{12}+Z_{22})}}\&ap;\frac{{\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="A2008100249680010H2.png"\; state="\{\{state\}\}">U</figure-callout>}}_0}{1+\frac{Z_{11}}{Z_{21}}}---\left(6\right)$

As can be seen, if M ₁Equal M ₂, I ₂Be 0.U ₂Be the voltage of output, one of basic function of the present invention is exactly to require the power output signal big as far as possible to the output load, that is to say, requires U2 big as far as possible, from formula (6) as can be seen, if Z ₂₁Much larger than Z ₁₁, that is to say L ₂₁Will be much larger than L ₁₁, U ₂Value just may be near U ₀

From top analysis result, the present invention selects to adopt following principle for transformer parameter:

1) L ₂₁Will be much larger than L ₁₁, L ₁₁As far as possible little, L ₂₁Big as far as possible, still, generally speaking, load impedance is 75 ohm, R ₁₁Should also require L much smaller than 75 ohm ₁₁As far as possible little, on the other hand, consider the complexity of load impedance, behind the access load impedance, to R ₂₁Influence is little.

2) from (3) formula as can be seen, because L ₁₁And L ₁₂Product require to equal L ₂₁With L ₂₂Product, if L ₂₁Will be much larger than L ₁₁, then also require L ₁₂Will be much larger than L ₂₂, therefore, the present invention selects L ₂₁=10L ₁₁, L ₁₂=10L ₂₂

Above from three functions of the present invention 1) and 2) angle carried out design analysis, below from three functions of the present invention 3) angle carries out design analysis, promptly, the received signal that comes from output interface circuit 18, by offseting network 15, its signal attenuation is very little, guarantees to be input to signal big as far as possible of receiving circuit 17.During analysis, suppose that input signal is U ₂, U ₀Signal source is regarded short circuit as, sets up electric current and voltage equation (7) and (8) of circuit of the present invention, separates this equation and gets:

From formula (10) result, I ₂Be the electric current that flow in the input circuit, realize being input to signal big as far as possible of receiving circuit 17 if desired.Be I ₂Big as far as possible, must make that denominator is as far as possible little, because last surface analysis has required M ₁Equal M ₂, therefore, if Z ₂₁Equal Z ₁₁+ Z ₀, consider Z ₂₁Much larger than Z ₁₁, compare Z ₂₁, Z ₁₁Can ignore, therefore, Z ₂₁Should select to approximate greatly Z ₀, i.e. impedance matching.

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="A2008100249680009H1.png,A2008100249680010H2.png"\; state="\{\{state\}\}">U</figure-callout>}}_2=M_2{I}_2+Z_{21}{I}_3---\left(7\right)\\ {\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="A2008100249680009H1.png,A2008100249680010H2.png"\; state="\{\{state\}\}">U</figure-callout>}}_2=-M_1{I}_2+({\mathrm{<figure-callout\; id="11"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{11}+Z_0)I_1---\left(8\right)\\ ({\mathrm{<figure-callout\; id="12"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{12}+Z_{22}+Z_1)I_2=M_1{I}_1+M_2{I}_1---\left(9\right)\end{array}\right.$

$I_2=\frac{(\frac{M_2}{Z_{21}}+\frac{M_1}{{\mathrm{<figure-callout\; id="11"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{11}+Z_0})U_2}{(\frac{{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A2008100249680009H1.png,A2008100249680010H2.png"\; state="\{\{state\}\}">M</figure-callout>}}_2^2}{Z_{21}}-\frac{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A2008100249680010H2.png"\; state="\{\{state\}\}">M</figure-callout>}}_1^2}{{\mathrm{<figure-callout\; id="11"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{11}+{\mathrm{<figure-callout\; id="0"\; label="Z"\; filenames="A2008100249680010H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_0}+{\mathrm{<figure-callout\; id="12"\; label="Z"\; filenames="A2008100249680009H2.png"\; state="\{\{state\}\}">Z</figure-callout>}}_{12}+Z_{22}+Z_1)}---\left(10\right)$

Below case study on implementation has been described in detail utility model of the present invention in conjunction with the accompanying drawings, and those skilled in the art can make the many variations example to utility model of the present invention according to the above description.Thereby some details among the embodiment should not constitute the qualification to utility model of the present invention.

Claims (2)

1, a kind of transmission duplex interface circuit of suitable compound impedance medium, comprise output power amplifier (1), impedance matching network module, balanced network module, offset mixed-media network modules mixed-media, output interface circuit, input power amplifier (6), it is characterized in that, the impedance matching network module comprises a transformer, offsets the transformer that mixed-media network modules mixed-media comprises two butt joints.

2, the transmission duplex interface circuit of a kind of suitable compound impedance medium according to claim 1 is characterized in that, described balanced network module is made of the source electrode coil of a transformer.

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