CN104123571B - A kind of carrier cancellation circuit and RFID reader based on RFID reader - Google Patents
A kind of carrier cancellation circuit and RFID reader based on RFID reader Download PDFInfo
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- CN104123571B CN104123571B CN201310143262.9A CN201310143262A CN104123571B CN 104123571 B CN104123571 B CN 104123571B CN 201310143262 A CN201310143262 A CN 201310143262A CN 104123571 B CN104123571 B CN 104123571B
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Abstract
The present invention is applied to circuit field, more particularly to a kind of carrier cancellation circuit and RFID reader based on RFID reader.In the course of work of RFID reader, controller adjusts the impedance of impedance inverter circuit, to adjust the reception signal that demodulator is received, when the power that power detector is detected is minimum, the reflected signal for representing the impedance inverter circuit is optimal to the neutralization effect for leaking carrier signal, so as to which demodulator is easier to demodulate correct label signal.
Description
Technical field
The invention belongs to circuit field, more particularly to a kind of carrier cancellation circuit and RFID read-write based on RFID reader
Device.
Background technology
It is well known that in the course of work of ultrahigh frequency radio frequency identification (RFID) reader, electronic tag is to read write line return signal process
In, read write line also needs transmitting carrier signal to provide energy to electronic tag., can not because the carrier signal that read write line is launched is very strong
What is avoided has portion of carriers signals leakiness to receiving channel, and the carrier signal that this partial compromise comes is returned much larger than label
Letter in reply number, so as to cause the receiving sensitivity of read write line to decline.Recent years, in order to overcome this problem, leads in super high frequency technique
Domain occurs in that carrier cancellation technology.The principle of method be produce one and leakage carrier amplitude be equal, opposite in phase signal and
Leak carrier phasor to be added, weaken the interference for even eliminating carrier signal, and the signal returned on label does not produce influence.The party
The course of work of method is after carrier signal is amplified by power amplifier (Power Amplifier, PA), by directional coupler coupling
The signal for unifying Partial Power is used as the source signal of offseting signal.The source signal is input to Vector Modulation circuit, Vector Modulation electricity
Road is adjusted to the amplitude and phase of input signal, produces, offseting signal of opposite in phase equal with leakage carrier amplitude.Support
The signal that disappears is added with the receiving end signal of isolator by combiner, the carrier signal for weakening and stopping a leak, so
After be input to demodulator circuit and microcontroller, obtain label data.
Carrier cancellation circuit design above-mentioned is the addition on the basis of conventional ultra high frequency RFID reader scheme
The circuits such as Vector Modulation circuit, combiner and isolator.The implementation of Vector Modulation circuit in this circuit design
Mainly there are two, one is using existing Vector Modulation chip, the second is using traditional Vector Modulation circuit；The former lacks
Point be Vector Modulation chip price costly, single-chip price will be more than hundred yuan, along with combiner and isolator, sternly
Design cost is added again, and traditional Vector Modulation circuit realiration is complex, Vector Modulation effect is not again obvious.The opposing party
Face, Vector Modulation algorithm is also more complicated, while needing I, Q two-way analog signal to control.Although so this design can
Weaken and carrier wave of stopping a leak interference, but global design has that cost of hardware design is high, hardware design difficulty is larger, software control
The shortcoming that algorithm processed is more complicated, debugging difficulty is big, is not appropriate for batch production.
The content of the invention
It is an object of the invention to provide a kind of carrier cancellation circuit based on RFID reader, it is desirable to provide one kind is based on
The carrier cancellation circuit of ultrahigh frequency radio frequency identification (RFID) reader, the carrier cancellation circuit is by changing impedance to reduce or eliminate leakage carrier wave
Influence, demodulate label signal.
The present invention is achieved in that a kind of carrier cancellation circuit based on RFID reader, described to be based on RFID read-write
The carrier cancellation circuit of device includes the modulation circuit for being used to generate carrier signal, the carrier cancellation electricity based on RFID reader
Road external antenna, the carrier cancellation circuit based on RFID reader also includes：
Be connected with the modulation circuit and with go side always, for by the carrier signal from the straight-through end send to
The directional coupler of the antenna；
It is connected with the isolation end of the directional coupler, letter is received for being obtained from the isolation end of the directional coupler
Number, and from the demodulator of the receiving signal demodulation outgoing label signal；
It is connected with the input coupling of the demodulator, for entering to the part signal being coupled to from the reception signal
The power detector of row power detection；
It is connected with the demodulator and the power detector, for receiving the label signal, adjustment impedance conversion electricity
The microcontroller of the impedance on road；And
The impedance inverter circuit being connected respectively with the coupled end and the microcontroller of the directional coupler.
The present invention also provides a kind of RFID reader, and the RFID reader includes the above-mentioned load based on RFID reader
Ripple bucking circuit.
In the present invention, in RFID reader, controller adjusts the impedance of impedance inverter circuit, is connect with adjusting demodulator
The reception signal received, when the power that power detector is detected is minimum, represents the reflected signal of the impedance inverter circuit
It is optimal to the neutralization effect of leakage carrier signal, so that, demodulator is easier to demodulate correct label signal.
Brief description of the drawings
Fig. 1 is the circuit structure diagram of the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader；
Fig. 2 is a kind of impedance conversion electricity in the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader
The circuit diagram on road；
Fig. 3 is another impedance conversion in the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader
The circuit diagram of circuit；
Fig. 4 is the carrier wave based on RFID reader provided in an embodiment of the present invention based on impedance inverter circuit described in Fig. 3
The physical circuit figure of bucking circuit；
After Fig. 5 is the impedance adjustment of a cycle of impedance inverter circuit provided in an embodiment of the present invention, impedance conversion electricity
The cycle traversal trajectory diagram of the reflected signal on road.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, it is right below in conjunction with drawings and Examples
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
Fig. 1 shows the structure of the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader, in order to just
In explanation, the part related to the embodiment of the present invention is illustrate only, details are as follows.
A kind of carrier cancellation circuit based on RFID reader, the carrier cancellation circuit based on RFID reader includes
Modulation circuit for generating carrier signal, the carrier cancellation circuit external antenna based on RFID reader is described to be based on
The carrier cancellation circuit of RFID reader also includes：
Be connected with the modulation circuit and with go side always, for by the carrier signal from the straight-through end send to
The directional coupler 2 of the antenna；
It is connected with the isolation end of the directional coupler 2, letter is received for being obtained from the isolation end of the directional coupler 2
Number, and from the demodulator of the receiving signal demodulation outgoing label signal；
It is connected with the input coupling of the demodulator, for entering to the part signal being coupled to from the reception signal
The power detector 3 of row power detection；
It is connected with the demodulator and the power detector 3, for receiving the label signal, adjustment impedance conversion electricity
The microcontroller 4 of the impedance on road 1；And
The impedance inverter circuit 1 being connected respectively with the coupled end and the microcontroller 4 of the directional coupler 2.
, can if impedance inverter circuit 1 adjusts impedance using the variable capacitance of numeral adjustment as one embodiment of the invention
To be directly connected to the microcontroller 4 and impedance inverter circuit 1.
As another embodiment of the present invention, if impedance inverter circuit 1 adjusts impedance using the variable capacitance of simulation adjustment,
Also need to add D/A converter between the microcontroller 4 and impedance inverter circuit 1, the digital analog converter is used for institute
The data signal for stating the output of microcontroller 4 is converted to analog signal, to control impedance inverter circuit 1.
As one embodiment of the invention, the carrier cancellation circuit also includes：
It is connected to the power amplifier 7 between the input of the output end of the modulation circuit and the directional coupler 2.
Fig. 2 shows that a kind of impedance in the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader becomes
The circuit of circuit 1 is changed, for convenience of description, the part related to the embodiment of the present invention is illustrate only, details are as follows.
As another embodiment of the present invention, the impedance inverter circuit 1 includes：
Variable capacitance C1, variable capacitance C2, variable capacitance C3, filter capacitor C4, filter capacitor C5, filter inductance L1, filter
Ripple inductance L2, filter inductance L3 and resistance R1；
The first end of the variable capacitance C1 and the second end connect the coupled end and ground of the directional coupler 2 respectively, described
Filter inductance L1 is in parallel with the variable capacitance C1, and the variable capacitance C2, the filter capacitor C4 are respectively connected to described
Between variable capacitance C1 first end and the first end of the filter inductance L2, the second termination filter of the filter inductance L2
Ripple electric capacity C5 first end, the variable capacitance C3, the filter inductance L3, the resistance R1 are both connected to the filter capacitor
Between C5 first end and ground.
By adjusting variable capacitance C1, variable capacitance C2, variable capacitance C3 electric capacity, the resistance of impedance inverter circuit 1 is adjusted
It is anti-.
Fig. 3 shows that another impedance in the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader becomes
The circuit of circuit 1 is changed, for convenience of description, the part related to the embodiment of the present invention is illustrate only, details are as follows.
As one embodiment of the invention, the impedance inverter circuit 1 includes：
First tunable capacitor chip U1, the second tunable capacitor chip U2, the 3rd tunable capacitor chip U3, filter capacitor C31,
Filter capacitor C32, filter capacitor C33, filter inductance L34, filter inductance L35, filter inductance L36, resistance R37 and resistance
R38；
The first end of the filter inductance L34 is the impedance conversion pin RF_F of the impedance inverter circuit 1, the impedance
Conversion pin RF_F connects the coupled end of the directional coupler 2, and the second end of the filter inductance L34 is grounded, and described first can
Electric capacity chip U1 clock pins SCL, data pin SDA, strobe pin SEN_A is adjusted to connect the microcontroller 4 respectively, described the
One tunable capacitor chip U1 positive pole capacitor pin RF+, negative pole capacitor pin RF- connects the first of the filter inductance L34 respectively
End, clock pins SCL, data pin SDA, the strobe pin SEN_B of the second tunable capacitor chip U2 connect described respectively
Microcontroller 4, positive pole capacitor pin RF+, the negative pole capacitor pin RF- of the second tunable capacitor chip U2 connect the filter respectively
The first end of ripple inductance L34 first end, the filter inductance L35, the filter capacitor C31 is connected to second adjustable electric
Between the positive pole capacitor pin RF+ and negative pole capacitor pin RF- that hold chip U2, the filter capacitor C32 is connected to the filtering
Between inductance L35 the second end and the filter inductance L36 first end, the clock pins of the 3rd tunable capacitor chip U3
SCL, data pin SDA, strobe pin SEN_C connect the microcontroller 4, the positive pole of the 3rd tunable capacitor chip U3 respectively
Capacitor pin RF+, negative pole capacitor pin RF- connect respectively the filter inductance L36 first end, the resistance R37 with it is described
Filter inductance L36 is in parallel, and the filter capacitor C33 is connected to the of the first end of the filter inductance L36 and the resistance R38
Between one end, the second end of the filter inductance L36, the second end of the resistance R38 are grounded.
It should be noted that passing through the first tunable capacitor chip U1, the second tunable capacitor chip U2, the 3rd tunable capacitor core
Piece U3, adjusts the impedance of impedance inverter circuit 1.
With reference to Fig. 3, Fig. 4 shows the specific of the carrier cancellation circuit provided in an embodiment of the present invention based on RFID reader
Circuit, for convenience of description, illustrate only the part related to the embodiment of the present invention, details are as follows.
As one embodiment of the invention, the carrier cancellation circuit also includes：
Output end respectively with the power amplifier 7, the input of the directional coupler 2 are connected, for filtering out load
The filter circuit 5 of ripple signal, the filter circuit 5 includes：
Filter capacitor C41, filter capacitor C42, filter capacitor C43, filter inductance L48 and filtering chip U4；
The first end of the filter capacitor C41, the second end connect respectively the power amplifier 7 output end, the filter
Ripple inductance L48 is connected between the first end of the filter capacitor C41 and the filter capacitor C42 first end, the filtering
Electric capacity C42 the second end ground connection, the filter capacitor C43 is connected to the first end and the filtering core of the filter capacitor C42
Between piece U4 filtering input pin RF_IN, the filtering output pin RF_OUT of the filtering chip U4 connects the directional couple
The input of device 2.
As one embodiment of the invention, the directional coupler 2 includes：
Capacitance C44, capacitance C45 and the first directional couple chip U6；
The first end of the capacitance C44, the second end meet the filtering output pin RF_ of the filtering chip U4 respectively
OUT, the first directional couple chip U6 carrier wave input pin IN, the straight-through pin of the first directional couple chip U6
DIR, coupled pin COU, isolation pin ISO connect antenna, the second end of the capacitance C45, the demodulator respectively, described
Capacitance C45 the first termination impedance conversion pin RF_F.
As one embodiment of the invention, the carrier cancellation circuit also includes：
Isolation end, the input of the power detector 3 respectively with the directional coupler 2 is connected, for coupling part
Divide the termination power 6 for receiving signal, the termination power 6 includes：
Capacitance C46, capacitance C47, shunt resistance R49, shunt resistance R50 and the second directional couple chip U5；
The first end of the capacitance C46, the second end connect the isolation pin of the first directional couple chip U6 respectively
ISO, the second directional couple chip U5 coupling input pin, the straight-through output pin of the second directional couple chip U5
DIR, power coupled pin COU, power isolation pin ISO connect the second end of the capacitance C47, the shunt resistance respectively
The first end of R49 first end, the shunt resistance R50, the first termination demodulator of the capacitance C47 is described
Shunt resistance R50 the second end ground connection, the second termination power detector 3 of the shunt resistance R49.
As one embodiment of the invention, the power detector 3 includes：
Divider resistance R51 and power detection chip U8；
The divider resistance R51 is connected between the second end of the shunt resistance R49 and ground, the power detection chip
U8 detection input pin P_IN, detection output pin P_OUT connects the second end of the shunt resistance R49, microcontroller respectively
4。
As one embodiment of the invention, the microcontroller 4 includes：
Microcontroller chip U7；
The clock pins SCL of the microcontroller chip U7 connects the clock pins of the first tunable capacitor chip U1 respectively
SCL, the second tunable capacitor chip U2 clock pins SCL, the 3rd tunable capacitor chip U3 clock pins SCL, the micro-control
Coremaking piece U7 data pin SDA connects the data pin SDA of the first tunable capacitor chip U1, the second tunable capacitor core respectively
Piece U2 data pin SDA, the 3rd tunable capacitor chip U3 data pin SDA, the microcontroller chip U7 the first gating
Pin SEN_A, the second strobe pin SEN_B, the 3rd strobe pin SEN_C, demodulated signal pin DEM and power detection pin
ADC connects the strobe pin SEN_A of the first tunable capacitor chip U1, the second tunable capacitor chip U2 strobe pin respectively
SEN_B, the 3rd tunable capacitor chip U3 strobe pin SEN_C, the output end of the demodulator, the power detection chip U8
Detection output pin P_OUT.
In order to preferably explain the present invention, with reference to Fig. 3, Fig. 4, the first tunable capacitor is used with the first tunable capacitor chip U1
Chip PE64904, the second tunable capacitor chip U2 use the second tunable capacitor chip PE64904, the 3rd tunable capacitor chip U3
Using the 3rd tunable capacitor chip PE64904, the first directional couple chip U6 using the first directional couple chip DC0900A05,
Second directional couple chip U5 uses power detection chip using the second directional couple chip HHM2602, power detection chip U8
Exemplified by MAX4003, illustrate the operation principle of the carrier cancellation circuit based on RFID reader：
Modulation circuit generates carrier signal, and the carrier signal carries out power amplification by power amplifier 7PA, and PA is by power
Carrier signal after amplification is input to first by the first directional couple chip DC0900A05 carrier signal input pin IN and determined
To coupling chip DC0900A05.In the first directional couple chip DC0900A05, pass through the first directional couple chip
DC0900A05 straight-through pin DIR, antenna sends carrier signal, meanwhile, pass through the first directional couple chip DC0900A05's
The carrier signal that coupled pin COU is coupled to the transmitting portion of impedance inverter circuit 1；In addition, also partial carrier wave signal is leaked to
First directional couple chip DC0900A05 isolation pin ISO, simultaneously as the impedance Incomplete matching of antenna end, part is carried
Ripple signal reflex is returned, and the reflected signal reflected is coupled to the first directional couple chip DC0900A05 isolation pin
ISO, is partly leaked to the first directional couple chip DC0900A05 isolation pin ISO carrier signal and the reflected signal
Composition leakage carrier signal.The feedback signal including label signal that the leakage carrier signal, antenna are received, impedance conversion electricity
The reflected signal composition on road receives signal, the isolation pin ISO that the reception signal passes through the first directional couple chip DC0900A05
Output.
More optimizedly, in the directional couple chip DC0900A05 of power amplifier 7 and first carrier signal input pin IN
Between introduce filter circuit 5, the filter capacitor C41 that is included by the filter circuit 5, filter capacitor C42, filter capacitor C43,
The low pass filter of filter inductance L48 and filtering chip U4 compositions, the effect with blocking and LPF.
Demodulator is demodulated to the reception signal received, to obtain label signal；Microcontroller chip U7 demodulation letter
Number pin DEM receives the label signal of demodulator output.
More optimizedly, isolating between pin ISO in demodulator and the first directional couple chip DC0900A05, introduce
Termination power 6, the second directional couple chip HHM2602 included by the termination power 6 straight-through output pin DIR is to demodulation
Device inputs most reception signal, meanwhile, by the second directional couple chip HHM2602 power coupled pin COU to work(
Rate detection chip MAX4003 detection input pin P_IN provides part and receives signal, is detected with power detection chip MAX4003
The part is received the power of signal and exported with the form of analog voltage signal to microcontroller chip U7 power detection pin
ADC。
First directional couple chip DC0900A05 is coupled by coupled pin COU to the transmitting portion of impedance inverter circuit 1
Carrier signal；Microcontroller chip U7 passes through the first strobe pin SEN_A, the second strobe pin SEN_B, the 3rd strobe pin SEN_
C controls the first tunable capacitor chip PE64904, the second tunable capacitor chip PE64904, the 3rd tunable capacitor chip PE64904
Choose, pass through data pin SDA send electric capacity adjust signal, the first tunable capacitor chip PE64904, the second tunable capacitor core
The tunable capacitor chip adjustment electric capacity being selected in piece PE64904, the 3rd tunable capacitor chip PE64904, to adjust impedance change
Change the impedance of circuit 1；So as to which the amplitude and phase of the carrier signal for the part coupling that adjustment impedance inverter circuit 1 reflects are with anti-
The reflected signal of feedpoint impedance translation circuit.Meanwhile, microcontroller chip U7 power detection pin ADC receiving power detection chips
The analog voltage signal of MAX4003 outputs；By that analogy, microcontroller chip U7 controls the first tunable capacitor chip PE64904, the
Two tunable capacitor chip PE64904, the 3rd tunable capacitor chip PE64904 electric capacity adjustment, to complete the impedance of a cycle
The impedance adjustment (including amplitude and phase) of translation circuit 1, to change the reflected signal of impedance inverter circuit, meanwhile, microcontroller
The analog voltage signal that chip U7 power detection pin ADC receiving power detection chip MAX4003 are exported in the cycle；Most
Afterwards, microcontroller chip U7 controls the first tunable capacitor chip PE64904, the second tunable capacitor chip PE64904, the 3rd adjustable electric
Hold chip PE64904 adjustment electric capacity, to reach analog voltage signal that microcontroller chip U7 power detection pin ADC is received
The minimum value of the analog voltage signal exported for the cycle.For example：Fig. 5 shows the resistance of a cycle of impedance inverter circuit 1
After anti-adjustment, the amplitude and phase of the reflected signal of impedance inverter circuit, in fig. 5, it is assumed that b points are leakage carrier signal, are adjusted
The impedance of whole impedance inverter circuit 1 is to select e points as the reflected signal of impedance inverter circuit；So as to the impedance conversion electricity of e points
The reflected signal on road maximally, even can fully offset the leakage carrier signal of b points, and then, demodulator demodulates most accurate
True label signal.More optimizedly, RFID reader is allowed in advance away from electronic tag, so that electronic tag is not fed back including mark
The feedback signal of signal is signed, with the impedance adjustment for a cycle for completing impedance inverter circuit 1, microcontroller chip U7 power is examined
Survey pin ADC and receive the cycle, power detection chip MAX4003 outputs analog voltage signal, find out cycle output
The impedance of the minimum value of analog voltage signal and corresponding impedance inverter circuit 1；So as to receive letter in follow-up demodulator demodulation
Number when, can be easier to demodulate correct label signal.
As another embodiment of the present invention, present invention also offers a kind of RFID reader, the RFID reader includes
The above-mentioned carrier cancellation circuit based on RFID reader.
In embodiments of the present invention, in RFID reader, the impedance of impedance inverter circuit is adjusted by controller, to adjust
The reflected signal of whole impedance inverter circuit, the reflected signal of the impedance inverter circuit is used to offset leakage carrier signal, so that, solution
Device is adjusted to be easier to demodulate correct label signal.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention
Any modifications, equivalent substitutions and improvements made within refreshing and principle etc., should be included in the scope of the protection.
Claims (9)
1. a kind of carrier cancellation circuit based on RFID reader, the carrier cancellation circuit based on RFID reader includes using
In the modulation circuit of generation carrier signal, the carrier cancellation circuit external antenna based on RFID reader, it is characterised in that
The carrier cancellation circuit based on RFID reader also includes：
It is connected with the modulation circuit and with go side always, for the carrier signal to be sent to described from the straight-through end
The directional coupler of antenna；
It is connected with the isolation end of the directional coupler, signal is received for being obtained from the isolation end of the directional coupler, and
From the demodulator of the receiving signal demodulation outgoing label signal；
It is connected with the input coupling of the demodulator, for carrying out work(to the part signal being coupled to from the reception signal
The power detector of rate detection；
It is connected with the demodulator and the power detector, for receiving the label signal, adjustment impedance inverter circuit
The microcontroller of impedance；
The impedance inverter circuit being connected respectively with the coupled end and the microcontroller of the directional coupler, the impedance conversion
The reflected signal of circuit is used to offset leakage carrier signal
And it is connected to the power amplifier between the input of the output end of the modulation circuit and the directional coupler.
2. the carrier cancellation circuit as claimed in claim 1 based on RFID reader, it is characterised in that the impedance conversion electricity
Road includes：
Variable capacitance C1, variable capacitance C2, variable capacitance C3, filter capacitor C4, filter capacitor C5, filter inductance L1, filtered electrical
Feel L2, filter inductance L3 and resistance R1；
The first end of the variable capacitance C1 and the second end connect the coupled end and ground of the directional coupler, the filtered electrical respectively
Feel L1 it is in parallel with the variable capacitance C1, the variable capacitance C2, the filter capacitor C4 be respectively connected to described in can power transformation
Hold between C1 first end and the first end of the filter inductance L2, the second termination filter capacitor of the filter inductance L2
C5 first end, the variable capacitance C3, the filter inductance L3, the resistance R1 are both connected to the of the filter capacitor C5
Between one end and ground.
3. the carrier cancellation circuit as claimed in claim 1 based on RFID reader, it is characterised in that the impedance conversion electricity
Road includes：
First tunable capacitor chip U1, the second tunable capacitor chip U2, the 3rd tunable capacitor chip U3, filter capacitor C31, filtering
Electric capacity C32, filter capacitor C33, filter inductance L34, filter inductance L35, filter inductance L36, resistance R37 and resistance R38；
The first end of the filter inductance L34 is the impedance conversion pin (RF_F) of the impedance inverter circuit, the impedance change
The coupled end that pin (RF_F) connects the directional coupler is changed, the second end of the filter inductance L34 is grounded, and described first is adjustable
Electric capacity chip U1 clock pins, data pin, strobe pin connect the microcontroller, the first tunable capacitor chip respectively
U1 positive pole capacitor pin, negative pole capacitor pin connect respectively the filter inductance L34 first end, second adjustable electric
Appearance chip U2 clock pins, data pin, strobe pin connect the microcontroller, the second tunable capacitor chip U2 respectively
Positive pole capacitor pin, negative pole capacitor pin connect the first end of the filter inductance L34, the of the filter inductance L35 respectively
One end, the filter capacitor C31 is connected to the positive pole capacitor pin and negative pole capacitor pin of the second tunable capacitor chip U2
Between, the filter capacitor C32 be connected to the second end of the filter inductance L35 and the filter inductance L36 first end it
Between, the clock pins of the 3rd tunable capacitor chip U3, data pin, strobe pin connect the microcontroller respectively, described
3rd tunable capacitor chip U3 positive pole capacitor pin, negative pole capacitor pin connect respectively the filter inductance L36 first end,
Ground, the resistance R37 is in parallel with the filter inductance L36, and the filter capacitor C33 is connected to the of the filter inductance L36
Between one end and the resistance R38 first end, the second end of the filter inductance L36, the second end of the resistance R38 connect
Ground.
4. the carrier cancellation circuit as claimed in claim 3 based on RFID reader, it is characterised in that the carrier cancellation electricity
Road also includes：
Output end respectively with the power amplifier, the input of the directional coupler are connected, for filtering out carrier signal
Filter circuit, the filter circuit includes：
Filter capacitor C41, filter capacitor C42, filter capacitor C43, filter inductance L48 and filtering chip U4；
The first end of the filter capacitor C41, the second end connect respectively the power amplifier output end, the filtered electrical
Sense L48 is connected between the first end of the filter capacitor C41 and the filter capacitor C42 first end, the filter capacitor
C42 the second end ground connection, the filter capacitor C43 is connected to the first end and the filtering chip U4 of the filter capacitor C42
Filtering input pin between, the filtering output pin of the filtering chip U4 connects the input of the directional coupler.
5. the carrier cancellation circuit as claimed in claim 4 based on RFID reader, it is characterised in that the directional coupler
Including：
Capacitance C44, capacitance C45 and the first directional couple chip U6；
The first end of the capacitance C44, the second end connect the filtering output pin of the filtering chip U4, described first respectively
Directional couple chip U6 carrier wave input pin, the straight-through pin of the first directional couple chip U6, coupled pin, isolation are drawn
Pin connects antenna, the second end of the capacitance C45, the demodulator respectively, and the first termination of the capacitance C45 is described
Impedance conversion pin (RF_F).
6. the carrier cancellation circuit as claimed in claim 5 based on RFID reader, it is characterised in that the carrier cancellation electricity
Road also includes：
Isolation end, the input of the power detector respectively with the directional coupler is connected, for described in coupling unit
The termination power of signal is received, the termination power includes：
Capacitance C46, capacitance C47, shunt resistance R49, shunt resistance R50 and the second directional couple chip U5；
The first end of the capacitance C46, the second end connect the isolation pin, described of the first directional couple chip U6 respectively
Second directional couple chip U5 coupling input pin, straight-through output pin, the power coupling of the second directional couple chip U5
Close pin, power isolation pin connect the second end of the capacitance C47 respectively, it is the first end of the shunt resistance R49, described
Shunt resistance R50 first end, the first termination demodulator of the capacitance C47, the second of the shunt resistance R50
End ground connection, the second termination power detector of the shunt resistance R49.
7. the carrier cancellation circuit as claimed in claim 6 based on RFID reader, it is characterised in that the power detector
Including：
Divider resistance R51 and power detection chip U8；
The divider resistance R51 is connected between the second end of the shunt resistance R49 and ground, the power detection chip U8's
Detection input pin, detection output pin connect the second end of the shunt resistance R49, microcontroller respectively.
8. the carrier cancellation circuit as claimed in claim 7 based on RFID reader, it is characterised in that the microcontroller bag
Include：
Microcontroller chip U7；
The clock pins of the microcontroller chip U7 connect the clock pins of the first tunable capacitor chip U1 respectively, second adjustable
The clock pins of electric capacity chip U2 clock pins, the 3rd tunable capacitor chip U3, the data pin of the microcontroller chip U7
Connect the data pin of the first tunable capacitor chip U1 respectively, it is the second tunable capacitor chip U2 data pin, the 3rd adjustable
Electric capacity chip U3 data pin, the first strobe pin of the microcontroller chip U7, the second strobe pin, the 3rd gating draw
Pin, demodulated signal pin and power detection pin connect the strobe pin of the first tunable capacitor chip U1 respectively, second adjustable
Electric capacity chip U2 strobe pin, the 3rd tunable capacitor chip U3 strobe pin, the output end of the demodulator, the power
Detection chip U8 detection output pin.
9. a kind of RFID reader, it is characterised in that the RFID reader includes claim 1 to any institute of claim 8
The carrier cancellation circuit based on RFID reader stated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310143262.9A CN104123571B (en) | 2013-04-23 | 2013-04-23 | A kind of carrier cancellation circuit and RFID reader based on RFID reader |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310143262.9A CN104123571B (en) | 2013-04-23 | 2013-04-23 | A kind of carrier cancellation circuit and RFID reader based on RFID reader |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104123571A CN104123571A (en) | 2014-10-29 |
| CN104123571B true CN104123571B (en) | 2017-09-08 |
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| CN107770106A (en) * | 2016-08-15 | 2018-03-06 | 天津科畅慧通信息技术有限公司 | The system and method that a kind of self-interference offsets |
| CN106710042A (en) * | 2016-12-20 | 2017-05-24 | 盐城工学院 | Detection system and method based on FRID |
| CN109583252A (en) * | 2018-11-01 | 2019-04-05 | 锐捷网络股份有限公司 | A kind of carrier cancellation circuit and RFID reader |
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| CN202362811U (en) * | 2011-12-02 | 2012-08-01 | 江苏军一物联网股份有限公司 | Ultrahigh frequency RFID self-interference elimination device |
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| JP4842695B2 (en) * | 2006-04-27 | 2011-12-21 | 株式会社日立製作所 | Dynamic management system |
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