CN109327245B - Transceiver and card reader - Google Patents
Transceiver and card reader Download PDFInfo
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- CN109327245B CN109327245B CN201810939339.6A CN201810939339A CN109327245B CN 109327245 B CN109327245 B CN 109327245B CN 201810939339 A CN201810939339 A CN 201810939339A CN 109327245 B CN109327245 B CN 109327245B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B5/00—Near-field transmission systems, e.g. inductive loop type
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
- G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
- G06K7/10297—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
- G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
- G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
- G06K7/10336—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers the antenna being of the near field type, inductive coil
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
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- H04B5/48—
Abstract
The invention provides a transmitting and receiving device and a card reader. The transceiver comprises a micro control unit, a transceiver circuit, a positive detection circuit, a negative detection circuit and a differential amplification circuit, wherein: the receiving and transmitting circuit is connected with a differential transmitting interface of the micro control unit; the first input end of the forward detection circuit is connected with a first node in the transceiver circuit, and the second input end of the forward detection circuit is connected with a second node in the transceiver circuit; a first input end of the negative detection circuit is connected with the first node, and a second input end of the negative detection circuit is connected with the second node; the output end of the positive detection circuit is connected with the first input end of the differential amplification circuit, and the output end of the negative detection circuit is connected with the second input end of the differential amplification circuit; the output end of the differential amplifying circuit is connected with the receiving interface of the micro control unit. The invention can effectively reduce the influence of large signal carrier interference on the sensitivity of the receiving and transmitting device in the prior art and can effectively improve the communication distance.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a transceiver and a card reader having the transceiver.
Background
Near field communication, also known as short-range wireless communication, is a short-range high-Frequency wireless communication technology, which allows contactless point-to-point data transmission and data exchange between electronic devices, and is evolved from contactless Radio Frequency Identification (RFID), and the basis thereof is RFID and interconnection technology. The radio frequency identification system comprises an RFID electronic tag and an RFID card reader. The RFID electronic tag and the RFID reader realize space (non-contact) coupling of radio frequency signals through the coupling element. And in the coupling channel, energy transfer and data exchange are realized according to a time sequence relation. The RFID card reader is in wireless communication with the RFID electronic tag through the antenna, and can read or write the tag identification code and the memory data.
The basic working principle of the RFID is as follows: after entering a magnetic field, the RFID electronic Tag receives a radio frequency signal sent by an RFID card reader, product information (Passive Tag or Passive Tag) stored in an RFID electronic Tag chip is sent out by means of energy obtained by induced current, and the RFID card reader reads and decodes the information and sends the information to a central information system for related data processing.
Because the RFID card reader needs to receive the weak response signal of the RFID electronic tag while the transmission power can provide enough energy for the passive tag, the transmission power and the sensitivity of the transceiver of the RFID card reader are both required to be higher, and particularly when a large card reading distance is required, the card reading distance, the transmission power and the sensitivity of the transceiver of the RFID card reader are not linearly improved, but are required to be exponentially improved.
The coupling type of the radio frequency signal between the RFID card reader and the RFID electronic tag is two types:
(1) inductive coupling, namely realizing coupling through a space high-frequency alternating magnetic field according to an electromagnetic induction law;
(2) electromagnetic backscattering coupling, namely, according to the space propagation rule of electromagnetic waves, the emitted electromagnetic waves are reflected after touching a target and carry back target information.
In the prior art, when a radio frequency signal between an RFID card reader and an RFID electronic tag is inductively coupled, the problem that a carrier signal sent by a transmitter per se has large interference on a receiving and transmitting device per se exists.
Disclosure of Invention
The present invention has been made in view of the above problems, and aims to provide a transmitting and receiving device and a card reader having the transmitting and receiving device, which at least partially solve the above problems.
According to an aspect of the present invention, there is provided a transceiver apparatus including a micro control unit, a transceiver circuit, a positive detection circuit, a negative detection circuit, and a differential amplifier circuit, wherein:
the receiving and transmitting circuit is connected with a differential transmitting interface of the micro control unit;
a first input end of the forward detection circuit is connected with a first node in the transceiver circuit, a second input end of the forward detection circuit is connected with a second node in the transceiver circuit, and output signals of the first node and the second node are differential signals;
a first input end of the negative detection circuit is connected with the first node, and a second input end of the negative detection circuit is connected with the second node;
the output end of the positive detection circuit is connected with the first input end of the differential amplification circuit, and the output end of the negative detection circuit is connected with the second input end of the differential amplification circuit;
and the output end of the differential amplification circuit is connected with the receiving interface of the micro control unit.
Illustratively, the forward detector circuit comprises a forward first detector circuit and a forward second detector circuit connected in parallel, and/or
The negative detection circuit comprises a negative first detection circuit and a negative second detection circuit which are connected in parallel.
Illustratively, the forward first detection circuit comprises a forward first unidirectional conducting circuit, a forward first filter circuit and a forward first coupling capacitor which are connected in series, wherein a first end of the forward first unidirectional conducting circuit is conducted from a first end to a second end in a forward direction, and a first end of the forward first unidirectional conducting circuit is connected with the first node;
the forward second detection circuit comprises a forward second unidirectional conduction circuit, a forward second filter circuit and a forward second coupling capacitor which are connected in series, the forward second unidirectional conduction circuit is conducted from a first end to a second end in a forward direction, and the first end of the forward second unidirectional conduction circuit is connected with the second node;
and the second end of the forward first coupling capacitor and the second end of the forward second coupling capacitor are connected to form a forward parallel end, and the forward parallel end is connected with the first input end of the differential amplification circuit.
Illustratively, the forward first filter circuit comprises a forward first parallel circuit composed of a forward first filter capacitor and a forward first load resistor, a first end of the forward first parallel circuit is connected with a second end of the forward first unidirectional conducting circuit, the first end of the forward first parallel circuit is further connected with a first end of the forward first coupling capacitor, and the second end of the forward first parallel circuit is grounded; and/or the presence of a gas in the gas,
the forward second filter circuit comprises a forward second parallel circuit consisting of a forward second filter capacitor and a forward second load resistor, the first end of the forward second parallel circuit is connected with the second end of the forward second unidirectional conduction circuit, the first end of the forward second parallel circuit is also connected with the first end of the forward second coupling capacitor, and the second end of the forward second parallel circuit is grounded.
Illustratively, the negative first detection circuit comprises a negative first unidirectional conducting circuit, a negative first filter circuit and a negative first coupling capacitor which are connected in series, a first end of the negative first unidirectional conducting circuit is conducted in a negative direction to a second end, and a first end of the negative first unidirectional conducting circuit is connected with the first node;
the negative second detection circuit comprises a negative second one-way conduction circuit, a negative second filter circuit and a negative second coupling capacitor which are connected in series, the first end of the negative second one-way conduction circuit is conducted from the first end to the second end in a negative way, and the first end of the negative second one-way conduction circuit is connected with the second node;
the second end of the negative first coupling capacitor and the second end of the negative second coupling capacitor are connected to form a negative parallel end, and the negative parallel end is connected with the second input end of the differential amplification circuit.
Illustratively, the negative first filter circuit includes a negative first parallel circuit composed of a negative first filter capacitor and a negative first load resistor, a first end of the negative first parallel circuit is connected to a second end of the negative first unidirectional conducting circuit, the first end of the negative first parallel circuit is further connected to a first end of the negative first coupling capacitor, and the second end of the negative first parallel circuit is grounded; and/or the presence of a gas in the gas,
the negative second filter circuit comprises a negative second parallel circuit consisting of a negative second filter capacitor and a negative second load resistor, a first end of the negative second parallel circuit is connected with a second end of the negative second unidirectional conduction circuit, a first end of the negative second parallel circuit is further connected with a first end of the negative second coupling capacitor, and a second end of the negative second parallel circuit is grounded.
Illustratively, the differential amplification circuit includes a first follower circuit, a second follower circuit, and a baseband amplification circuit, wherein:
the first end of the first follower circuit is connected with the forward parallel end, and the second end of the first follower circuit is connected with the first input end of the baseband amplification circuit;
the first end of the second follower circuit is connected with the negative parallel end, and the second end of the second follower circuit is connected with the second input end of the baseband amplifying circuit;
and the output end of the baseband amplifying circuit is connected with the receiving interface.
Illustratively, the baseband amplifying circuit is disposed inside the micro control unit, the micro control unit includes a first differential receiving interface and a second differential receiving interface,
the second end of the first follower circuit is connected with the first input end of the baseband amplifying circuit through the first differential receiving interface,
and the second end of the second follower circuit is connected with the second input end of the baseband amplifying circuit through the second differential receiving interface.
Illustratively, the differential amplifying circuit is arranged inside the micro control unit, the micro control unit comprises a first differential receiving interface and a second differential receiving interface,
the forward parallel end is connected with the first input end of the differential amplifying circuit through the first differential receiving interface,
the negative parallel end is connected with the second input end of the differential amplification circuit through the second differential receiving interface.
Illustratively, the transceiver further includes an input resistor, a first end of the input resistor is connected to the output end of the differential amplifier circuit, and a second end of the input resistor is connected to the receiving interface.
According to an aspect of the present invention, there is provided a card reader, which includes the above-mentioned transceiver.
The transceiver of the invention improves the signal quality of the detection circuit by using the fully differential signal, and reduces the performance requirement of the receiver circuit. The influence of large signal carrier interference of the near field communication transceiver on the sensitivity of the transceiver in the prior art can be effectively reduced, so that the communication distance of the transceiver is effectively increased.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail embodiments of the present invention with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings, like reference numbers generally represent like parts or steps.
Fig. 1 shows a schematic block diagram of a transceiving apparatus 100 according to an embodiment of the present invention;
fig. 2 shows a schematic circuit diagram of a transceiving apparatus 100 according to an embodiment of the present invention;
FIG. 3 shows a schematic circuit diagram of a filter circuit according to one embodiment of the invention;
fig. 4 shows a circuit diagram of a transceiving apparatus according to another embodiment of the present invention; and
fig. 5 shows a circuit diagram of a transceiving apparatus according to still another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely a subset of embodiments of the invention and not all embodiments of the invention, with the understanding that the invention is not limited to the example embodiments described herein.
In order to solve the above-mentioned problems, embodiments of the present invention provide a transceiver and a card reader having the transceiver.
The existing front end of the transceiver can simply realize the extraction of the baseband envelope signal through a diode detection circuit. The amplitude modulated wave is passed through a detector diode, and due to the unidirectional conductivity characteristics of the detector diode, the negative portion of the amplitude modulated signal is cut off, leaving only the positive portion thereof. At this time, if an average value is taken (low-pass filtering) in each signal period of the amplitude-modulated signal, an obtained wave packet (envelope) of the amplitude-modulated signal is a baseband low-frequency signal, so that the demodulation (detection) function is realized. However, the prior art has the problem that the interference of the carrier signal sent by the transmitter to the own transceiver is large. A transmitting/receiving apparatus according to an embodiment of the present invention will be described in detail with reference to fig. 1.
Fig. 1 shows a schematic block diagram of a transceiving apparatus 100 according to an embodiment of the present invention. As shown in fig. 1, the transceiver apparatus 100 includes: a micro control unit 110, a transceiver circuit 120, a positive detector circuit 130, a negative detector circuit 140, and a differential amplifier circuit 150. The transceiver circuit 120 is connected to the differential transmission interface of the mcu 110. A first input terminal of the forward detection circuit 130 and a first node V of the transceiver circuit 120EMC_PA second input terminal of the forward detection circuit 130 is connected to a second node V of the transceiver circuit 120EMC_NIs connected, wherein the first node VEMC_PAnd a second node VEMC_NThe output signal of (a) is a differential signal. First input terminal and first node V of negative detection circuit 140EMC_PConnected to a second input of negative detection circuit 140 and a second node VEMC_NAnd (4) connecting. An output terminal of the positive detection circuit 130 is connected to a first input terminal of the differential amplification circuit 150, and an output terminal of the negative detection circuit 140 is connected to a second input terminal of the differential amplification circuit 150. The output of the differential amplifier circuit 150 is connected to the receiving interface of the micro control unit 110. The transceiver utilizes the differential signal to improve the signal quality of the detection circuit, and is beneficial to increasing the overall robustness of the system. Moreover, the influence of signal carrier interference on the sensitivity of the transceiver can be effectively reduced, and the communication distance of the transceiver is further effectively increased.
Fig. 2 shows a schematic circuit diagram of a transceiving apparatus 100 according to an embodiment of the present invention. As shown in FIG. 2, the micro-control unit 110 may be implemented by a card reader chip. The card reader chip may include a plurality of interfaces. Wherein, RX is a receiving interface, TX1 and TX2 are the first and second differential transmitting interfaces, respectively, and GND is a ground terminal. TVSS is a transient voltage pulse suppressor interface. The transceiver circuit 120 may be an existing transceiver circuit for a card reader or a future-generation transceiver circuit for a card reader, which is not limited by the present invention. For example, the transceiver circuit 120 includes an electromagnetic compatibility filter unit 121, a matching circuit 122, and an antenna 123. For example, the electromagnetic compatibility filter unit 121, the matching circuit 122, and the 1 antenna 23 are connected in series. First node VEMC_PAnd a second node VEMC_NBetween the electromagnetic compatibility filter unit 121 and the matching circuit 122. VTX1、VTX2、VEMC_P、VEMC_N、VANT_P、VANT_N、VEVP_P、VEVP_NRespectively, are nodes in the circuit. Inductor LEMCAnd a capacitor CEMCTogether forming an electromagnetic compatibility filter unit 121. Capacitor CSERAnd a capacitor CPARTogether forming a matching circuit 122. The capacitors, inductors and resistors in the rightmost dashed box collectively form the antenna 123. As can be seen from fig. 2, the output of the emc filter unit 121 and the matching circuit 122 are symmetrical differential structures, and the receiving circuit is single-ended receiving.
In one embodiment, as illustrated in FIG. 2The forward detector circuit 130 includes a forward first detector circuit and a forward second detector circuit connected in parallel, and detects a differential signal VEMC_PAnd VEMC_NDetection is performed. The negative-sense circuit 140 includes a negative first-sense circuit and a negative second-sense circuit connected in parallel, and applies a difference signal VEMC_PAnd VEMC_NDetection is performed. Because the signal generated by the card reading reaction at a longer distance in the near field communication is smaller, compared with single-side detection, the invention improves the signal quality of the detection circuit by utilizing the fully differential detection, thereby reducing the performance requirement on the receiving circuit.
In one embodiment, as shown in FIG. 2, the forward first detection circuit comprises a series connection of forward first unidirectional conductive circuits DPPA forward first filter circuit 131 and a forward first coupling capacitor CRX_PP. Forward first unidirectional conduction circuit DPPIs forward conducted from the first end to the second end, and a forward first unidirectional conduction circuit DPPFirst end of and a first node VEMC_PAnd (4) connecting. The forward second detection circuit includes a forward second unidirectional conductive circuit DP connected in seriesNA forward second filter circuit 132 and a forward second coupling capacitor CRX_PN. Forward second unidirectional conducting circuit DPNIs forward conducted from the first end to the second end, and is forward conducted to the second unidirectional conducting circuit DPNFirst end and second node VEMC_NAnd (4) connecting. Forward first coupling capacitor CRX_PPAnd a forward second coupling capacitor CRX_PNIs connected to form a forward parallel terminal VEVP_PForward parallel terminal VEVP_PIs connected to a first input terminal of the differential amplification circuit 150. Through a forward first unidirectional conduction circuit DPPAnd a forward second unidirectional conduction circuit DPNRespectively extracting differential signals VEMC_PAnd VEMC_NThen low-pass filtered by the forward first filter circuit 131 and the forward second filter circuit 132, respectively, and finally passed through the forward first coupling capacitor CRX_PPAnd a forward second coupling capacitor CRX_PNAnd carrier cancellation is realized. Thus, the positive end of the differential input, i.e., the forward parallel end, is formed by differential detectionVEVP_P. Under the condition of a certain transmitter power supply voltage, the output power of the transmitter is improved by using differential detection. On the other hand, the interference noise is greatly reduced through the carrier cancellation among the differential signals, and the main frequency component is farther away from the baseband signal frequency, so that the interference noise is more easily filtered by the next-stage circuit.
Forward first unidirectional conduction circuit DPPAnd/or a forward second unidirectional conduction circuit DPNThe device can be realized by a device with a unidirectional conduction function, such as a diode, a triode or a Metal Oxide Semiconductor (MOS) tube, and can also be realized by a combined circuit formed by a plurality of elements with the unidirectional conduction function.
Fig. 3 shows a schematic circuit diagram of a filter circuit according to an embodiment of the invention. As shown in FIG. 3, the forward first filter circuit 131 includes a forward first filter capacitor CFILT_pAnd a forward first load resistance RFILT_pForming a forward first parallel circuit. The first end of the forward first parallel circuit and the forward first unidirectional conduction circuit DPPThe first end of the forward first parallel circuit is also connected with a forward first coupling capacitor CRX_PPAnd the second end GND of the forward first parallel circuit is grounded. Alternatively, the circuit configuration of the forward second filter circuit 132 is identical to that of the forward first filter circuit 131. As shown in FIG. 3, the forward second filter circuit 132 includes a forward second filter capacitor CFILT_pAnd a forward second load resistor RFILT_pForming a forward second parallel circuit. As shown in fig. 2, the first end of the forward second parallel circuit and the forward second unidirectional conducting circuit DPNIs connected with the first end of the forward second parallel circuit, and the first end of the forward second parallel circuit is also connected with a forward second coupling capacitor CRX_PNIs connected to the first terminal of the forward second parallel circuit, and the second terminal GND of the forward second parallel circuit is connected to ground. Forward first filter capacitor CFILT_pAnd a forward second filter capacitor CFILT_pIs a high frequency filter capacitor, and the above-mentioned slave differential signal V is filtered by forward first filter circuit 131 and forward second filter circuit 132EMC_PAnd VEMC_NThe extracted upper envelope signal is fedAnd the low-pass filtering is carried out, so that the interference of noise is reduced, and the influence of the noise on the effective communication distance is reduced.
In one embodiment, as shown in FIG. 2, the negative first detection circuit comprises a negative first unidirectional conducting circuit DN connected in seriesPA negative first filter circuit 141 and a negative first coupling capacitor CRX_NP. Negative first one-way conduction circuit DNPIs negatively conducted from the first end to the second end, and is negatively conducted to a first one-way conduction circuit DNPFirst end of and a first node VEMC_PAnd (4) connecting. The negative second detection circuit comprises a negative second unidirectional conduction circuit DN connected in seriesNA negative second filter circuit 142 and a negative second coupling capacitor CRX_NN. Negative second unidirectional conducting circuit DNNIs negatively conducted from the first end to the second end, and is negatively conducted by a second one-way conduction circuit DNNFirst end and second node VEMC_NAnd (4) connecting. Negative first coupling capacitor CRX_NPAnd a negative second coupling capacitor CRX_NNIs connected to form a negative parallel terminal VEVP_NNegative parallel terminal VEVP_NIs connected to a second input terminal of the differential amplifying circuit 150. Through a negative first unidirectional conducting circuit DNPAnd a negative second unidirectional conducting circuit DNNRespectively extracting differential signals VEMC_PAnd VEMC_NThen low-pass filtered by the negative first filter circuit 141 and the negative second filter circuit 142, respectively, and finally passed through the negative first coupling capacitor CRX_NPAnd a negative second coupling capacitor CRX_NNAnd carrier cancellation is realized. Thus, the negative parallel terminal V, which is the negative terminal of the differential input, is formed by the differential detection methodEVP_N. Under the condition of a certain transmitter power supply voltage, the output power of the transmitter is improved by using differential detection. On the other hand, the interference noise is greatly reduced through the carrier cancellation among the differential signals, and the main frequency component is farther away from the baseband signal frequency, so that the interference noise is more easily filtered by the next-stage circuit.
Negative first one-way conduction circuit DNPAnd/or negative direction second unidirectional conduction circuit DNNCan adopt a diodeAnd a device having a unidirectional conduction function, such as a triode or a Metal Oxide Semiconductor (MOS) transistor, may also be implemented by using a combinational circuit composed of a plurality of elements having a unidirectional conduction function.
Alternatively, the circuit configuration of the negative first filter circuit 141 is identical to that of the positive first filter circuit 131. As shown in FIG. 3, the negative first filter circuit 141 includes a negative first filter capacitor CFILT_pAnd a negative first load resistance RFILT_pForming a negative first parallel circuit. The first end of the negative first parallel circuit and the negative first unidirectional conducting circuit DNPThe first end of the negative first parallel circuit is also connected with a negative first coupling capacitor CRX_NPIs connected to the first terminal of the negative first parallel circuit, and the second terminal GND of the negative first parallel circuit is grounded. Alternatively, the negative direction second filter circuit 142 has a circuit configuration identical to that of the negative direction first filter circuit 141. As shown in FIG. 3, the negative second filter circuit 142 includes a negative second filter capacitor CFILT_pAnd a negative second load resistance RFILT_pForming a negative second parallel circuit. The first end of the negative second parallel circuit and the negative second unidirectional conduction circuit DNNIs connected with the first end of the negative second parallel circuit and is also connected with a negative second coupling capacitor CRX_NNIs connected to the first terminal of the negative second parallel circuit, and the second terminal GND of the negative second parallel circuit is grounded. Negative first filter capacitor CFILT_pAnd a negative second filter capacitor CFILT_pIs a high frequency filter capacitor, and the secondary differential signal V is filtered by a negative first filter circuit 141 and a negative second filter circuit 142EMC_PAnd VEMC_NThe extracted lower envelope signal is low-pass filtered, and the interference of noise is reduced, so that the influence of the noise on the effective communication distance is reduced.
It should be understood that the circuit structure shown in fig. 3 is only an example of the filter circuit, and the positive first filter circuit 131, the positive second filter circuit 132, the negative first filter circuit 141, and the negative second filter circuit 142 in this embodiment may also be other circuits having filter functions, for example, the above filter circuits may be equivalently modified to obtain other junctionsA filter circuit is constructed. For example, a forward first load resistor RFILT_pAnd a capacitor (not shown) to form a series circuit, which is connected with the forward first filter capacitor CFILT_pThe formed parallel circuit may also serve as the forward first filter circuit 131. Similarly, the positive second filter circuit 132, the negative first filter circuit 141, and the negative second filter circuit 142 can be obtained, and are not described herein again.
In one embodiment, as shown in fig. 2, the differential amplification circuit 150 includes a first follower circuit 151, a second follower circuit 152, and a baseband amplification circuit 153. Wherein, the first end of the first follower circuit 151 is connected with the forward direction parallel end VEVP_PThe second terminal of the first follower circuit 151 is connected to the first input terminal of the baseband amplifier circuit 153. The first terminal and the negative parallel terminal V of the second follower circuit 152EVP_NA second terminal of the second follower circuit 152 is connected to a second input terminal of the baseband amplifier circuit 153. The output of the baseband amplifier circuit 152 is connected to the reception interface RX. The difference signal V obtained by the above-mentioned difference detectionEVP_PAnd VEVP_NAfter passing through respective follower circuits, the signal quality is improved, and the overall robustness of the system is increased.
Alternatively, the first follower circuit 151 and/or the second follower circuit 152 may be added with a certain resistance to form a homodyne amplifier with a certain gain, and then form a differential input of the baseband amplifier circuit 153. Therefore, the signal amplitude is improved, and the communication distance of the transceiver is effectively increased.
In one embodiment, as shown in fig. 2, the transceiver further comprises an input resistor RRX. Input resistance RRXIs connected to the output of the differential amplifier circuit 150, and an input resistor RRXIs connected to the receive interface RX.
Fig. 4 shows a circuit diagram of a transceiving apparatus according to another embodiment of the present invention. As shown in fig. 4, the baseband amplifying circuit 153 is disposed inside the micro control unit 110, and the micro control unit 110 includes a first differential receiving interface RX _ P and a second differential receiving interface RX _ N. A second terminal of the first follower circuit 151 is connected to a first input terminal of the baseband amplifier circuit 153 through a first differential receiving interface RX _ P, and a second terminal of the second follower circuit 152 is connected to a second input terminal of the baseband amplifier circuit through a second differential receiving interface RX _ N. Therefore, the number of components and circuit wiring is reduced, and the integration level and the reliability of the transceiver are improved.
Fig. 5 shows a circuit diagram of a transceiving apparatus according to still another embodiment of the present invention. As shown in fig. 5, the differential amplifier circuit 150 is disposed inside the micro control unit 110, and the micro control unit 110 includes a first differential receiving interface RX _ P and a second differential receiving interface RX _ N. Forward parallel terminal VEVP_PIs connected with the first input end of the differential amplifying circuit 150 through the first differential receiving interface RX _ P, and has a negative parallel end VEVP_NAnd is connected to the second input terminal of the differential amplifying circuit 150 through the second differential receiving interface RX _ N. Therefore, the number of components and circuit wiring is further reduced, and the integration level and the reliability of the transceiver are improved.
According to another aspect of the invention, a card reader is also provided. The wireless Communication device comprises the transceiver, and the card reader is, for example, a Near Field Communication (NFC) card reader, a high-frequency RFID card reader, an identity card reader, or the like. Compared with the prior art, the card reader with the transceiver can effectively increase the card reading distance on the premise of unchanged power.
The transceiver of the invention improves the signal quality of the detection circuit by using the fully differential signal, and reduces the performance requirement of the receiver circuit. The differential detection circuit also comprises a high-pass filter for filtering direct-current voltage generated by the detection circuit, and a low-pass filter for further filtering carrier signals, and noise interference is reduced through ripple cancellation, so that a low-ripple differential signal is generated for the baseband amplification circuit. The signal amplitude is increased relative to the single-side detected differential signal, the amplitude of the ripple is reduced and the main frequency component of the ripple is further away from the baseband signal frequency, and therefore is easier to filter by the baseband amplifier.
In conclusion, the transceiver of the invention increases the signal-to-noise ratio and reduces the influence of noise interference on the sensitivity of the transceiver. Therefore, the transceiver device can effectively reduce the situation that the sensitivity of the receiver is influenced by large interference of the signal carrier of the receiver in the traditional near field communication, and can effectively improve the communication distance of the transceiver.
It should be noted that in the above description of various embodiments, when two elements are "connected," the two elements may be directly connected or indirectly connected through one or more intervening elements/media. The manner in which the two elements are connected may include a contact manner or a non-contact manner. Equivalent substitutions or modifications of the above described example connections may be made by those skilled in the art, and such substitutions or modifications are intended to be within the scope of the present application.
Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the foregoing illustrative embodiments are merely exemplary and are not intended to limit the scope of the invention thereto. Those skilled in the art can make various changes and modifications in its features without departing from the scope and spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
The above description is only for the specific embodiment of the present invention or the description thereof, and the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the protection scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (11)
1. A transceiver device, comprising a micro control unit, a transceiver circuit, a positive detection circuit, a negative detection circuit, and a differential amplifier circuit, wherein:
the receiving and transmitting circuit is connected with a differential transmitting interface of the micro control unit;
a first input end of the forward detection circuit is connected with a first node in the transceiver circuit, a second input end of the forward detection circuit is connected with a second node in the transceiver circuit, and output signals of the first node and the second node are differential signals;
a first input end of the negative detection circuit is connected with the first node, and a second input end of the negative detection circuit is connected with the second node;
the output end of the positive detection circuit is connected with the first input end of the differential amplification circuit, and the output end of the negative detection circuit is connected with the second input end of the differential amplification circuit;
the output end of the differential amplification circuit is connected with the receiving interface of the micro control unit;
wherein the forward detection circuit comprises a forward first detection circuit and a forward second detection circuit connected in parallel, and/or
The negative detection circuit comprises a negative first detection circuit and a negative second detection circuit which are connected in parallel.
2. The transceiver device of claim 1, wherein:
the forward first detection circuit comprises a forward first unidirectional conduction circuit, a forward first filter circuit and a forward first coupling capacitor which are connected in series, wherein a first end of the forward first unidirectional conduction circuit is in forward conduction with a second end, and a first end of the forward first unidirectional conduction circuit is connected with the first node;
the forward second detection circuit comprises a forward second unidirectional conduction circuit, a forward second filter circuit and a forward second coupling capacitor which are connected in series, the forward second unidirectional conduction circuit is conducted from a first end to a second end in a forward direction, and the first end of the forward second unidirectional conduction circuit is connected with the second node;
and the second end of the forward first coupling capacitor and the second end of the forward second coupling capacitor are connected to form a forward parallel end, and the forward parallel end is connected with the first input end of the differential amplification circuit.
3. The transceiver device of claim 2, wherein:
the forward first filter circuit comprises a forward first parallel circuit consisting of a forward first filter capacitor and a forward first load resistor, a first end of the forward first parallel circuit is connected with a second end of the forward first unidirectional conduction circuit, a first end of the forward first parallel circuit is also connected with a first end of the forward first coupling capacitor, and a second end of the forward first parallel circuit is grounded; and/or the presence of a gas in the gas,
the forward second filter circuit comprises a forward second parallel circuit consisting of a forward second filter capacitor and a forward second load resistor, the first end of the forward second parallel circuit is connected with the second end of the forward second unidirectional conduction circuit, the first end of the forward second parallel circuit is also connected with the first end of the forward second coupling capacitor, and the second end of the forward second parallel circuit is grounded.
4. The transceiver device of claim 1, wherein:
the negative first detection circuit comprises a negative first one-way conduction circuit, a negative first filter circuit and a negative first coupling capacitor which are connected in series, the first end of the negative first one-way conduction circuit is conducted from the first end to the second end in a negative way, and the first end of the negative first one-way conduction circuit is connected with the first node;
the negative second detection circuit comprises a negative second one-way conduction circuit, a negative second filter circuit and a negative second coupling capacitor which are connected in series, the first end of the negative second one-way conduction circuit is conducted from the first end to the second end in a negative way, and the first end of the negative second one-way conduction circuit is connected with the second node;
the second end of the negative first coupling capacitor and the second end of the negative second coupling capacitor are connected to form a negative parallel end, and the negative parallel end is connected with the second input end of the differential amplification circuit.
5. The transceiver device of claim 4, wherein:
the negative first filter circuit comprises a negative first parallel circuit consisting of a negative first filter capacitor and a negative first load resistor, a first end of the negative first parallel circuit is connected with a second end of the negative first unidirectional conducting circuit, a first end of the negative first parallel circuit is also connected with a first end of the negative first coupling capacitor, and a second end of the negative first parallel circuit is grounded; and/or the presence of a gas in the gas,
the negative second filter circuit comprises a negative second parallel circuit consisting of a negative second filter capacitor and a negative second load resistor, a first end of the negative second parallel circuit is connected with a second end of the negative second unidirectional conduction circuit, a first end of the negative second parallel circuit is further connected with a first end of the negative second coupling capacitor, and a second end of the negative second parallel circuit is grounded.
6. The transceiver device of claim 2, wherein:
the negative first detection circuit comprises a negative first one-way conduction circuit, a negative first filter circuit and a negative first coupling capacitor which are connected in series, the first end of the negative first one-way conduction circuit is conducted from the first end to the second end in a negative way, and the first end of the negative first one-way conduction circuit is connected with the first node;
the negative second detection circuit comprises a negative second one-way conduction circuit, a negative second filter circuit and a negative second coupling capacitor which are connected in series, the first end of the negative second one-way conduction circuit is conducted from the first end to the second end in a negative way, and the first end of the negative second one-way conduction circuit is connected with the second node;
the second end of the negative first coupling capacitor and the second end of the negative second coupling capacitor are connected to form a negative parallel end, and the negative parallel end is connected with the second input end of the differential amplification circuit.
7. The transceiver device of claim 6, wherein the differential amplification circuit comprises a first follower circuit, a second follower circuit, and a baseband amplification circuit, wherein:
the first end of the first follower circuit is connected with the forward parallel end, and the second end of the first follower circuit is connected with the first input end of the baseband amplification circuit;
the first end of the second follower circuit is connected with the negative parallel end, and the second end of the second follower circuit is connected with the second input end of the baseband amplifying circuit;
and the output end of the baseband amplifying circuit is connected with the receiving interface.
8. The transceiver device of claim 7, wherein the baseband amplification circuit is disposed within the micro control unit, the micro control unit comprising a first differential receive interface and a second differential receive interface,
the second end of the first follower circuit is connected with the first input end of the baseband amplifying circuit through the first differential receiving interface,
and the second end of the second follower circuit is connected with the second input end of the baseband amplifying circuit through the second differential receiving interface.
9. The transceiver according to claim 7, wherein the differential amplifier circuit is disposed inside the micro control unit, the micro control unit comprises a first differential receiving interface and a second differential receiving interface,
the forward parallel end is connected with the first input end of the differential amplifying circuit through the first differential receiving interface,
the negative parallel end is connected with the second input end of the differential amplification circuit through the second differential receiving interface.
10. The transceiver according to any one of claims 1 to 5, further comprising an input resistor, wherein a first end of the input resistor is connected to the output terminal of the differential amplifier circuit, and a second end of the input resistor is connected to the receiving interface.
11. A card reader, characterized in that it comprises a transceiver device according to any one of claims 1-10.
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| CN201810939339.6A CN109327245B (en) | 2018-08-17 | 2018-08-17 | Transceiver and card reader |
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| CN201810939339.6A CN109327245B (en) | 2018-08-17 | 2018-08-17 | Transceiver and card reader |
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| CN109327245B true CN109327245B (en) | 2021-07-09 |
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| WO2023178563A1 (en) * | 2022-03-23 | 2023-09-28 | 京东方科技集团股份有限公司 | Antenna impedance matching design circuit and near-field communication circuit system |
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| JPS63104225A (en) * | 1986-10-21 | 1988-05-09 | Csk Corp | Tracking system for optical recording medium |
| JP4277613B2 (en) * | 2003-07-25 | 2009-06-10 | 富士ゼロックス株式会社 | Tag information reading method and apparatus |
| CN101529439B (en) * | 2006-10-19 | 2011-09-28 | Nxp股份有限公司 | Transceiving circuit for contactless communication |
| CN101404067B (en) * | 2008-08-19 | 2010-09-29 | 周必友 | UHF active-mode active electronic label communication system |
| CN203299838U (en) * | 2013-06-27 | 2013-11-20 | 深圳拓邦股份有限公司 | Card reading circuit and card reader |
| CN106096697A (en) * | 2016-06-17 | 2016-11-09 | 广州中大微电子有限公司 | A kind of RFID Micro Energy Lose high sensitivity demodulator circuit |
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