CN103427875B - Analog front end system of coaxial cable broadband access - Google Patents
Analog front end system of coaxial cable broadband access Download PDFInfo
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- CN103427875B CN103427875B CN201210274302.9A CN201210274302A CN103427875B CN 103427875 B CN103427875 B CN 103427875B CN 201210274302 A CN201210274302 A CN 201210274302A CN 103427875 B CN103427875 B CN 103427875B
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Abstract
An analog front end system of coaxial cable broadband access is provided. The analog front end system includes an analog front end and a full-hybrid line interface; the analog front end is provided with a transmitting closed circuit and a receiving closed circuit; the transmitting closed circuit is provided with a linear actuator; the linear actuator comprises a first output end and a second output end; one end of a first end resistor and one end of a second end resistor of the full-hybrid line interface are connected with the first output end and the second output end of the linear actuator; the other end of the first end resistor and the other end of the second end resistor of the full-hybrid line interface are connected with a first end and a second end of a balancing transformer; the full-hybrid line interface further comprises a replica impedance network; the replica impedance network includes a first resistor, a third resistor and a second impedor which are connected in series with one another; the resistance of the first resistor and the resistance of the third resistor are identical; one end of the first resistor is connected with the first output end of the linear actuator; one end of the third resistor is connected with the second output end of the linear actuator; and the full-hybrid line interface is provided with first connecting lines at two ends of the balancing transformer and is provided with second connecting lines at one end of the replica impedance network, wherein the first connecting lines and the second connecting line are connected with the analog front end.
Description
[technical field]
The invention belongs to electronic technology field, refer to the AFE (analog front end) system that a kind of coaxial cable broadband accesses especially.
[background technology]
Along with information technology, computer network universal, broadband network high speed development, access way emerges in an endless stream, and cable TV network is due to wide coverage, bandwidth, shows very strong competitiveness.Coaxial cable broadband access is that one utilizes cable television network coaxial cable, realizes the broadband access solution of high-performance bidirectional transfer of information.
How realizing high-quality information transmission, improving data transmission rate is all communication plan problem demanding prompt solutions.Data transmission rate for RX (reception) path of communication interface AFE (analog front end) depends primarily on RX signal strength signal intensity, background noise and interference.If order input reference noise is enough little, then AFE (analog front end) (AFE) significantly can not reduce the signal to noise ratio (SNR) of signal transmission, thus data transmission rate also can not by the restriction of AFE (analog front end).The Main Noise Sources of RX path is the strong signal noise that TX (transmission) path is introduced, and therefore effectively isolating RX and TX path is the Basic Ways improving transmission performance.In wireless application, usual employing duplexer, duplexer is connected to form by resistors match network by the filter of two different passband sections, and its effect sends signal and Received signal strength isolation, ensure the transmission of signal and receive and can carry out simultaneously, thus receiving and send and can share common antenna.But it is too large to introduce the obvious cost of duplexer in coaxial cable broadband access interface scheme.In addition in half-duplex application, analog switch scheme can also be adopted to isolate TX and RX signal, namely RX path is disconnected when sending, and TX path is disconnected when receiving, reasons such as logical effect but analog switch can be burst due to electric capacity and introduce extra noise, therefore real being necessary proposes a kind of AFE (analog front end) system effectively can isolating the coaxial cable broadband access of RX and TX signal.
[summary of the invention]
The object of the invention is the AFE (analog front end) system providing a kind of coaxial cable broadband to access, the interface scheme that mating band noise is eliminated, and ensures the reliability of Signal transmissions.
According to above-mentioned purpose, the AFE (analog front end) system implementing coaxial cable broadband of the present invention access comprises the full blend interface that AFE (analog front end) is connected with this AFE (analog front end), this AFE (analog front end) is provided with transmission path and receiving path, and transmission path is provided with a Linear actuator, and receiving path is provided with subtracter, wherein this Linear actuator comprises the first output and the second output, wherein this full blend interface comprises first end resistance, second end resistance and balancing transformer, wherein this first end resistance is connected with the second output with the first output of Linear actuator respectively with one end of the second end resistance, this first end resistance is then connected with the second end with the first end of balancing transformer respectively with the other end of the second end resistance, and this full blend interface also comprises a copy impedance network, this copy impedance network comprises the first resistance of series connection, second impedance and the 3rd resistance, wherein the first resistance is identical with the 3rd resistance, and one end of the first resistance is connected with the first output of Linear actuator, and one end of the 3rd resistance is connected with the second output of Linear actuator, and this full blend interface is provided with the first connecting line at the first end of balancing transformer and the second end, and the second connecting line is provided with in one end of copy impedance network, first connecting line is connected with the subtracter of the second connecting line with the receiving path of AFE (analog front end).
According to above-mentioned principal character, the number of turn of balancing transformer is arranged by the output voltage swing of the Linear actuator of AFE (analog front end) and final required output voltage swing, and the first resistance of copy impedance network and the 3rd resistance are configured according to first and second end resistance, and with first end resistance and the proportional relation of the second end resistance, second impedance is then configured according to transmission line characteristic impedance, and relation proportional with transmission line characteristic impedance.
According to above-mentioned principal character, first end resistance is equal with the second end resistance, and arranges according to the transmission line characteristic impedance (may be the combination of resistance, inductance and electric capacity) that balancing transformer maps back.
According to above-mentioned principal character, this balancing transformer centre tap and be provided with a capacitance.
According to above-mentioned principal character, the first end of this balancing transformer and the second end are respectively provided with an electric capacity.
According to above-mentioned principal character, the second connecting line is connected to the two ends of the second impedance of copy impedance network.
According to above-mentioned purpose, the AFE (analog front end) system implementing coaxial cable broadband of the present invention access comprises the half-duplex interface that AFE (analog front end) is connected with this AFE (analog front end), this AFE (analog front end) is provided with transmission path and receiving path, and transmission path is provided with a Linear actuator, wherein this Linear actuator comprises the first output and the second output, this half-duplex interface comprises two end resistance, the first end of these two end resistance is connected with the second output with the first output of Linear actuator respectively, and the second end of these two end resistance is connected with a balancing transformer, and this half-duplex interface is also respectively equipped with first and second connecting line at the second end of these two end resistance respectively, this first and second connecting line is connected with the receiving path of AFE (analog front end), during reception, transmission path is mourned in silence, during transmission, receiving path power-off or the processor unit be connected with the AFE (analog front end) system that this coaxial cable broadband accesses are selected not respond.
According to above-mentioned principal character, the number of turn of this balancing transformer is arranged by the output voltage swing of the Linear actuator of AFE (analog front end) and final required output voltage swing.
According to above-mentioned principal character, these two end resistance are equal, and arrange according to the characteristic impedance that balancing transformer maps back.
Compared with prior art, the AFE (analog front end) system implementing coaxial cable broadband of the present invention access is applicable to full duplex and half-duplex apply, and can adopt the noise of suitable interface scheme elimination transmission path introducing, thus guarantees that signal reliably transmits.
[accompanying drawing explanation]
Fig. 1 is the circuit structure diagram of the AFE (analog front end) system implementing coaxial cable broadband of the present invention access.
Fig. 2 is the circuit diagram of the full blend interface shown in Fig. 1.
Fig. 3 is the monolateral equivalent electric circuit of Fig. 2
Fig. 4 is the circuit structure diagram of the AFE (analog front end) shown in Fig. 1.
Fig. 5 is the subtraction circuit structure chart with programmable automation controller in receiving path in Fig. 4.
Fig. 6 is the circuit structure diagram of the second embodiment of the AFE (analog front end) system implementing coaxial cable broadband of the present invention access.
Fig. 7 is the circuit diagram of the half-duplex interface shown in Fig. 6.
[embodiment]
As most of high performance mixed signal AFE (analog front end), the artificial circuit part matched with the full blend interface of adaptive noise cancel-ation of the present invention also adopts fully differential structure (being with internal common mode to regulate).Although all circuit module of AFE (analog front end) (hereinafter referred to as AFE) all comprises common mode regulation and common mode inhibition, enter the required reasonable balance of load that the signal of AFE and AFE drive.When implementing, AFE must drive the load of a pair balance, if by output one termination AC deposition, and the scheme exported by the other end is worthless.Equally, the input of AFE also must meet certain balance requirement, uses the other end to be also worthless a termination AC deposition.
Further, when implementing, for consideration that is electric and adjustment aspect, AFE can be connected with transmission line (coaxial cable, twisted-pair feeder etc.) by a transformer, utilizes this transformer to realize the function such as electrical isolation, overvoltage protection.If be single-ended (as coaxial cable) for the communication channel itself that electrically (physics) connects, transformer can also as difference/single-ended converter (BALUN).
Refer to shown in Fig. 1, for implementing the circuit structure diagram of the AFE (analog front end) system of coaxial cable broadband of the present invention access, the AFE (analog front end) system implementing coaxial cable broadband of the present invention access comprises the full blend interface that AFE (analog front end) is connected with this AFE (analog front end), below will be described in detail to each module.
In the present embodiment, this full hybrid interface is applicable to full duplex applications, as the standard interface as telecommunication apparatus (xDSL); Meanwhile, be also applied to half-duplex, if TX path does not possess noise shielding function, and analogue echo elimination is unique selection.Should be noted herein, only send " zero " signal and can not produce good noise elimination function, because the noise of whole simulation TX path still exists.
As shown in Figure 2, the full blend interface shown in Fig. 1 comprises first and second end resistance R
bm1with R
bm2and balancing transformer 2, wherein this first and second end resistance R
bm1with R
bm2one end be connected with 301 with first and second output 300 of the Linear actuator 30 of AFE respectively, and this first end resistance R
bm1with the second end resistance R
bm2the other end be then connected with first and second end 200,201 of balancing transformer 2 respectively, so form a loop.
In addition, the full blend interface implementing adaptive noise cancel-ation of the present invention also comprises a copy impedance network 4, and this copy impedance network comprises the first resistance R of series connection
bm1', the second impedance Z
m' and the 3rd resistance R
bm3', wherein the first resistance R
bm1' and the 3rd resistance R
bm3' resistance is identical, and the first resistance R
bm1' one end be connected with the first output 300 of the Linear actuator 30 of AFE, and the 3rd resistance R
bm3' one end be connected with the second output 301 of the Linear actuator 30 of AFE.
In addition, the number of turn of above-mentioned transformer 2 is generally arranged by the output voltage swing of the Linear actuator 30 (LD) of AFE and final required output voltage swing.First end resistance R
bm1with the second end resistance R
bm2resistance equal, and the transmission line characteristic impedance (may be the combination of resistance, inductance and electric capacity, as being 75 Ω) usually mapped back according to transformer 2 is arranged.
First resistance R of copy impedance network 4
bm1' and the 3rd resistance R
bm3' according to first and second end resistance R
bm1with R
bm2be configured, and with first end resistance R
bm1with the second end resistance R
bm2proportional relation, and the second impedance Z
m' be then configured according to transmission line characteristic impedance, and relation proportional with transmission line characteristic impedance.
Utilize the full blend interface of above-mentioned adaptive noise cancel-ation, such as, will obtain 3.6V on 75 Ω coaxial cables 5 (coaxial cable be namely connected with the full blend interface of this adaptive noise cancel-ation)
pPexport, suppose that the output voltage swing of given Linear actuator 30 is 3.6V
pP, then can use 1:2 (boosting) transformer 2, first end resistance R is set simultaneously
bm1with the second end resistance R
bm2resistance be 75/4/2 (namely 9.375).In order to avoid ripple and phase deviation, transformer 2 should possess the blocking capacitor (i.e. capacitance 202) of 100 μ H inductance and a 100nF, in addition the first resistance R of copy impedance network 4
bm1' and the 3rd resistance R
bm3' be set to first and second end resistance R
bm1with R
bm2four times, the second impedance Z
m' equal 75 Ω, namely decline four times by transformer 2, thus the first resistance R
bm1' and the 3rd resistance R
bm3' four times need be risen.
Moreover for the ease of being connected with the subtracter 50 of receiving path (RX), the full blend interface of this adaptive noise cancel-ation loads first and second connecting line (describing in detail after holding), wherein the first connecting line V in two positions, place
iNand V
iPbe connected to first end and second end 200,201, the second connecting line H of transformer 2
yNand H
yPbe connected in copy impedance network 4 one end, be specifically connected to the second impedance Z
m' two ends, need to carry out suitable adjustment (namely two-way Received signal strength subtracts each other according to a certain percentage, removes noise wherein, and this function realizes in receiver inside) and, to be effectively separated RX/TX, realize return loss system requirements.The input resistance rated value of the reception amplifier (PGA) of receiving path is 150 Ω, and actual value is approximately 160 Ω (every one end of four input pins).
Because the TX passage of whole AFE is DC coupling, and communication system transformer is to DC current sense, therefore this transformer 2 centre tap and comprise a capacitance 202, so can effectively isolate DC electric current.Or, if this transformer 2 does not adopt tapped mode, then need respectively to add an electric capacity on the both sides of voltage device 2.
Referring to shown in Fig. 3, is the equivalent single-sided conductive paths of Fig. 2, in order to eliminate the signal reflex on transmission line, needs to connect a terminal impedance Z on coaxial cable 5
t(designing according to the principle of impedance matching).
Equiva lent impedance Z in Fig. 3
m"=1/2Z
m', equiva lent impedance Z
t'=(1/2N
2) Z
t(secondary terminal impedance is mapped to 1/2 of the equiva lent impedance on former limit, and wherein N is the turn ratio of transformer).During as full duplex applications, on transmission line, Signal reception and transmission can be carried out simultaneously, i.e. synchronization, and transmission line can exist Received signal strength (being designated as RX) simultaneously and send signal (being designated as TX).TX signal is provided by first and second output 300 and 301 end of the Linear actuator 30 of AFE.RX signal from transmission line, and is transferred to first and second end 200,201 (because transformer turns ratio is N, so be (1/N) * RX) of this balancing transformer 2 by balancing transformer 2.After monolateral equivalence, in figure 3, namely the port 500 of the Linear actuator 30 of AFE is 1/2TX in performance, and resistance R
bm1output 501 be (1/2N) RX.According to given signal source and potential-divider network, just H can be calculated
yPand V
iP.V
iP=(1/N) RX+ [Z
t'/2 (Z
t'+R
bm1)] TX, the i.e. partial pressures of TX on RX Signal averaging; H
yP=Z
m"/(R
bm1'+Z
m") TX, be only the dividing potential drop of TX, the output voltage of LD end is very little, so H
yPthe RX signal received is almost equal to zero.Receive this two paths of signals simultaneously, and parameter is made the appropriate adjustments (as described below), TX signal can be eliminated, obtain pure RX signal.
If it is 3.6VPP that Linear actuator 30 outputs signal the amplitude of oscillation, and hypothesis transmission line characteristic impedance is a pure resistance impedance, as 75 Ω.R is set
bm1=R
bm2=Z
t'=(1/2N
2) * 75, then TX has half loss on resistor network, first and second end 200,201 of this balancing transformer 2 obtaining 1/2*3.6VPP, in order to export 3.6VPP on the transmission line, then needing the transformer of a 1:2.Such R
bm1=R
bm2=Z
t'=75/4/2.So, V
iP=1/4RX+1/4TX.In order to realize Echo cancellation, R can be made
bm1'=Z
m"=Z
m'/2=75/2.Such H
yP=1/4TX.V
iP-H
yP=1/4RX, VI-HY=1/2RX, thus obtain pure RX signal, wherein VI=V
iP-V
iN, HY=H
yP-H
yN, VI-HY=1/2RX is the output after being converted to both-end.
As shown in Figure 4, for the coaxial cable broadband be connected with full blend interface accesses the circuit diagram of AFE (analog front end), wherein coaxial cable broadband access AFE (analog front end) comprises RX path and TX path, and wherein TX path comprises a DAC, a current-to-voltage convertor (IVC), low pass smoothing filter (SMF)/transmitting filter (TXF) and Linear actuator (LD) composition.RX path comprises subtracter, low pass anti-aliasing filter (AAF/PGA), an ADC signal buffer and an ADC of a band programmable automation controller.AFE is controlled by main frame by three line SPI (Serial Peripheral Interface, Serial Peripheral Interface (SPI)), and spi bus system is a kind of synchronous serial Peripheral Interface, and it makes main frame communicate with AFE in a serial fashion exchange message or control AFE.
Below respectively the modules of TX path and RX path is described.
In the specific implementation, the DAC of above-mentioned TX path adopts structure of current rudder, and therefore TX path needs to add IVC before smoothing filter, certainly, also IVC function can be built in SMF module.In order to drive 75 Ω line resistances, also need a LD being with power adjustment functions.
The current conversion that DAC exports is become voltage by current-to-voltage convertor (IVC).In order to realize high-performance, the output of DAC remains on below 1V usually, thus need in IVC built-in level change-over circuit (Lever Shifter).
Smoothing filter (transmitting filter, here spectrum limitations problem is not considered) be that a simple labor executes (Rausch) filter (being in form that a single-section filter adds negative-feedback circuit composition biquadratic filter), there is transfer function and the 0.5dB peak value of similar Chebyshev.Amplifier is traditional class-a amplifier, does not drive the requirement of big current.
Because the IVC (or possible external filter) of prime is with common mode regulation, so the pressure of TXF in process output common mode level can be much little.
Linear actuator is a simple sign-changing amplifier be made up of AB class amplifier, possess larger output stage can keep output voltage swing constant condition under drive nearly 20 Ω loads.
RX path comprises an integrated subtracter 50 (as shown in Figure 2) and programmable amplifier (PGA), a frequency overlapped-resistable filter (AAF), an ADC buffer and an ADC.If need driving external filter, then also need a RX buffer.
Subtracter 50 and PGA integrate, and two groups of input signals subtract each other to realize Echo cancellation by the subtracter 50 in RX.
PGA is used to amplify the key modules that obvious noise is not introduced in input.A key parameter of PGA is input noise level.Input reference noise requires to obtain by different modes.The best method wherein weighing PGA noiseproof feature finds out PGA and at different levelsly afterwards reduces degree to RX signal to noise ratio.If PGA has a more rational high-gain, then what almost can be ignored the contribution of noise below.If can accomplish that the intrinsic noise of PGA is lower than ambient noise, then whole RX passage can not reduce the signal to noise ratio of Received signal strength.If intrinsic noise level is suitable with line noise, then the signal to noise ratio of Received signal strength will be lowered 3dB.
When there being adjacency channel to exist, needing to add analog filter to eliminate undesired signal, and amplifying Received signal strength further, thus making full use of the dynamic range of ADC.ADC and analog/digital filter need be compromised consideration.
In the present embodiment, PGA is an input low noise amplifier, possesses quite large gain ranging.Be exactly a sign-changing amplifier and the extra resistance R being connected in parallel on input in essence
scomposition.
This PGA provides two groups of input interface (i.e. V
iPand V
iNwith H
yPand H
yN), for realizing strict half-duplex or Echo cancellation interface structure.Often organize input interface can forbid separately.
Due to the requirement of noise aspect, input resistance is sufficiently little, thus when the interface of modelled signal source and PGA, the impact of input resistance can not be ignored.So upper usually requirement of design keeps certain input resistance.
Resistance all in Fig. 5 is all (able to programme) that can adjust.In order to realize high-gain, R
iNfixing, by regulating feedback resistance R
fbobtain required gain, R
sinfinitely great.(such as there is requirement to the driving force of amplifier) in certain special cases, R
fbkeep constant, by regulating R
iNrealize required gain, now, by changing R
svalue keeps total input resistance.
The output offset electric current of amplifier can regulate automatically according to loading condition (feedback resistance).For this reason, the whole external loading situation seen according to PGA is increased extra output offset electric current and regulates by digital control interface.
In addition, PGA gain-crossover is comparatively large, needs adaptive compensation scheme.All resistance is all high resistant poly resistance.
RX buffer aims at the module driving external filter design.Adopt the structure (same amplifier, reusable) identical with IVC buffer, level conversion function in removing IVC buffer, gain ranging is strict controlled in 0-1.5dB, 0.5 step-length.
Frequency overlapped-resistable filter is that a simple labor executes filter, is similar to TXF, and adds gain control function on the basis of TXF function.
The common mode regulation of AAF adds a built-in side-play amount, common mode output level is reduced about 200mV, improves interface capability between ADC buffer.
After ADC buffer is connected to AAF, provide enough current capacity to drive ADC; The afterbody that ADC (analog-digital converter) is RX path, passes to system by the analog quantity after process.
In addition, this AFE (analog front end) also comprises Voltage Reference Buffer, bandgap reference voltage and biasing module and level shifting circuit.
After wherein Voltage Reference Buffer is connected on reference voltage module (i.e. REF) usually, for reference voltage provides enough driving forces, also can isolate reference source (especially digital module, by clock control with other modules simultaneously, beat large), maintain reference source and stablize.)
Various reference voltage needed for bandgap reference voltage module generation system on sheet, current offset generation module provides required bias current for each module of system, simultaneously also for current steering DAC provides reference current.
The reference voltage that on sheet, reference voltage module produces needs external decoupling capacitance, also by digital control forbidding internal reference, introduces outside reference by interface.
System adopts many power source designs (digital power, simulation low-voltage module power supply, simulated high-pressure modular power source), therefore needs various level shifting circuit to accept different electrical power supply module, realizes communicating of digital circuit and analog circuit.
When AFE (analog front end) is connected with full blend interface, the output of AFE (analog front end) respectively with first and second end resistance R
bm1with R
bm2connect, and this echo noise eliminates the connecting line V of full blend interface
iNand V
iPand H
yNand H
yPthen be connected with the PGA of receiving path, concrete operation principle, as above-mentioned, no longer describes in detail herein.
Refer to shown in Fig. 6, implement the circuit structure diagram of the second embodiment of the AFE (analog front end) system of coaxial cable broadband of the present invention access.The AFE (analog front end) system implementing coaxial cable broadband of the present invention access comprises the half-duplex interface that AFE (analog front end) is connected with this AFE (analog front end), this AFE (analog front end) is provided with transmission path and receiving path, and transmission path is provided with a Linear actuator, wherein this Linear actuator comprises the first output and the second output, this half-duplex interface comprises two end resistance, the first end of these two end resistance is connected with the second output with the first output of Linear actuator respectively, and the second end of these two end resistance is connected with a balancing transformer (as shown in Figure 2), and this half-duplex interface is also respectively equipped with first and second connecting line at the second end of these two end resistance respectively, this first and second connecting line is connected with the receiving path of AFE (analog front end).
Referring to shown in Fig. 7, is the circuit diagram of the half-duplex interface shown in Fig. 6, the equivalent inpnt resistance of RX path PGA in 150 Ω resistance corresponding diagram 6 wherein in figure, the Linear actuator LD in Linear actuator corresponding diagram 6 in TX path.
If system is strict half-duplex, and TX path carries noise cancellation, then do not need analogue echo to eliminate, then only need as shown in Figure 6, link resistance on two outputs of Linear actuator.
First embodiment shown in method for designing with Fig. 1 such as end resistance, transformer turns ratio in Fig. 7 is identical, and difference is: in RX side, only uses VI input, and HY input disconnects (namely NO_HY control signal connects high level).In the TX period, PGA mourns in silence, thus RX passage and the strong signal of TX is isolated; In the RX period, Linear actuator (LD) is mourned in silence, and makes its output low noise.Equally, if there is serious return loss requirement to exist, PGA input resistance also needs to do a little adjustment to the loading of connecting line.
As for the AFE (analog front end) shown in Fig. 6, it is identical with the function in Fig. 1, no longer describes in detail herein.
Be understandable that, for those of ordinary skills, can be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, and all these change or replace the protection range that all should belong to the claim appended by the present invention.
Claims (9)
1. the AFE (analog front end) system of a coaxial cable broadband access, it is characterized in that: the AFE (analog front end) system that this coaxial cable broadband accesses comprises the full blend interface that AFE (analog front end) is connected with this AFE (analog front end), this AFE (analog front end) is provided with transmission path and receiving path, and transmission path is provided with a Linear actuator (30), and receiving path is provided with subtracter (50), wherein this Linear actuator (30) comprises the first output (300) and the second output (301), it is characterized in that: the full blend interface of this adaptive noise cancel-ation comprises first end resistance (R
bm1), the second end resistance (R
bm2) and balancing transformer (2), wherein this first end resistance (R
bm1) and the second end resistance (R
bm2) one end be connected with the second output (301) with first output (300) of Linear actuator (30) respectively, and this first end resistance (R
bm1) and the second end resistance (R
bm2) the other end be then connected with the second end (201) with the first end (200) of balancing transformer (2) respectively, and the full blend interface of adaptive noise cancel-ation also comprises a copy impedance network (4), this copy impedance network (4) comprises the first resistance (R of series connection
bm1'), the second impedance (Z
m') and the 3rd resistance (R
bm3'), wherein the first resistance (R
bm1') and the 3rd resistance (R
bm3') resistance is identical, and the first resistance (R
bm1') one end be connected with first output (300) of Linear actuator (30), and the 3rd resistance (R
bm3') one end be connected with second output (301) of Linear actuator (30), and the first end (200) of the full blend interface of this adaptive noise cancel-ation in balancing transformer (2) and the second end (201) are provided with the first connecting line (V
iNand V
iP), and be provided with the second connecting line (H in one end of copy impedance network (4)
yNand H
yP), the first connecting line is connected with the subtracter (50) of AFE (analog front end) receiving path with the second connecting line.
2. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 1, is characterized in that: the number of turn of balancing transformer (2) is arranged by the output voltage swing of the Linear actuator (30) of AFE (analog front end) and final required output voltage swing.
3. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 1, is characterized in that: first end resistance (R
bm1) and the second end resistance (R
bm2) resistance is equal, and arrange according to the transmission line characteristic impedance that balancing transformer (2) maps back, and the first resistance (R of copy impedance network (4)
bm1') and the 3rd resistance (R
bm3') according to first end resistance (R
bm1) and the second end resistance (R
bm2) be configured, and with first end resistance (R
bm1) and the second end resistance (R
bm2) proportional relation, and the second impedance (Z
m') be then configured according to transmission line characteristic impedance, and relation proportional with transmission line characteristic impedance.
4. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 1, is characterized in that: this balancing transformer (2) centre tap and be provided with a capacitance (202).
5. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 1, is characterized in that: first end (200) and second end (201) of this balancing transformer (2) are respectively provided with an electric capacity.
6. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 1, is characterized in that: the second connecting line (H
yNand H
yP) be connected to the second impedance (Z
m') two ends.
7. the AFE (analog front end) system of a coaxial cable broadband access, it is characterized in that: the AFE (analog front end) system that this coaxial cable broadband accesses comprises the half-duplex interface that AFE (analog front end) is connected with this AFE (analog front end), this AFE (analog front end) is provided with transmission path and receiving path, and transmission path is provided with a Linear actuator, wherein this Linear actuator comprises the first output and the second output, this half-duplex interface comprises two end resistance, the first end of these two end resistance is connected with the second output with the first output of Linear actuator respectively, and the second end of these two end resistance is connected with a balancing transformer, and this half-duplex interface is also respectively equipped with first and second connecting line at the second end of these two end resistance respectively, this first and second connecting line is connected with the receiving path of AFE (analog front end), during reception, transmission path is mourned in silence, during transmission, receiving path power-off or the processor unit be connected with the AFE (analog front end) system that this coaxial cable broadband accesses are selected not respond.
8. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 7, is characterized in that: the number of turn of this balancing transformer is arranged by the output voltage swing of the Linear actuator of AFE (analog front end) and final required output voltage swing.
9. the AFE (analog front end) system of coaxial cable broadband access as claimed in claim 1, is characterized in that: these two end resistances are equal, and arrange according to the transmission line characteristic impedance that balancing transformer maps back.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210274302.9A CN103427875B (en) | 2012-08-03 | 2012-08-03 | Analog front end system of coaxial cable broadband access |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210274302.9A CN103427875B (en) | 2012-08-03 | 2012-08-03 | Analog front end system of coaxial cable broadband access |
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| Publication Number | Publication Date |
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| CN103427875A CN103427875A (en) | 2013-12-04 |
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| CN103795945A (en) * | 2014-03-09 | 2014-05-14 | 成都蒲江珂贤科技有限公司 | Household area type wireless signal transmitter |
| CN107561365A (en) * | 2017-08-15 | 2018-01-09 | 成都普诺科技有限公司 | Detect the monitor station of insulaion resistance |
| CN114430276B (en) * | 2021-12-28 | 2024-08-27 | 哈尔滨理工大学 | Piezoelectric signal general synchronous acquisition analog front end and voltage reference circuit thereof |
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| EP0806852A2 (en) * | 1996-05-09 | 1997-11-12 | Texas Instruments Incorporated | A multimode digital modem |
| EP0923822B1 (en) * | 1996-09-02 | 2002-11-13 | STMicroelectronics N.V. | Improvements in, or relating to, multi-carrier transmission systems |
| CN101283483A (en) * | 2005-08-10 | 2008-10-08 | 因特隆公司 | Bridging coaxial cable networks |
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| EP0806852A2 (en) * | 1996-05-09 | 1997-11-12 | Texas Instruments Incorporated | A multimode digital modem |
| EP0923822B1 (en) * | 1996-09-02 | 2002-11-13 | STMicroelectronics N.V. | Improvements in, or relating to, multi-carrier transmission systems |
| CN101283483A (en) * | 2005-08-10 | 2008-10-08 | 因特隆公司 | Bridging coaxial cable networks |
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