KR101231381B1 - Phase compensation system - Google Patents

Abstract

Phase compensation system according to the present invention comprises a phase synchronization circuit for generating an oscillation frequency signal; A phase adjuster for converting a phase of the oscillation frequency signal into a plurality of oscillation frequency signals having differentiated phases; A signal converter which converts the phase-converted oscillation frequency signal into an RF signal and converts it into an intermediate frequency signal; And a controller configured to transmit a control signal having a predetermined voltage level to control the phase shift operation of the phase adjuster.

According to the present invention, various phase corrections are possible, and bit errors generated during phase correction can be effectively prevented. In addition, the data recognition rate can be improved through a simple circuit configuration, and since there is no need for an additional device, there is an effect of providing an RFID system or a USN system that performs stable communication at low speed and at high speed.

Description

Phase compensation system

1 is a block diagram schematically showing the components of a typical RFID reader.

2 is a diagram illustrating a form in which a radio wave reception angle is changed when a general RFID reader communicates with a tag.

3 is a block diagram schematically illustrating components of a phase compensation system according to an embodiment of the present invention;

4 is a block diagram schematically illustrating the components of a first phase synchronization circuit portion of a phase compensation system according to an embodiment of the present invention;

FIG. 5 is a circuit diagram schematically illustrating components of a first phase adjuster included in a phase compensation system according to an exemplary embodiment of the present invention. FIG.

Figure 6 is a graph measuring the phase angle of the oscillation frequency signal converted by the phase compensation system according to an embodiment of the present invention.

FIG. 7 is a circuit diagram schematically illustrating components of a first signal conversion unit included in a phase compensation system according to an exemplary embodiment of the present invention. FIG.

8 is a graph illustrating a form in which a phase of an oscillation frequency signal is variously converted in a phase compensation system according to an exemplary embodiment of the present invention.

9 is a graph illustrating a form in which a phase of an intermediate frequency signal is variously converted in a phase compensation system according to an exemplary embodiment of the present invention.

Description of the Related Art

100: phase compensation system 105: first antenna

115: low noise amplifier 117: balloon circuit

120: first signal conversion section 130: first phase synchronization circuit section

140: first phase adjuster 150: first power amplifier

152: second power amplifier 154: demodulator

160: control unit 165: modulation unit

170: third power amplifier 172: fourth power amplifier

180: second signal conversion unit 200: second phase synchronization circuit unit

210: second phase adjustment unit 190: power amplifier module

194: second antenna

The present invention relates to a phase compensation system applicable to a radio frequency identification (RFID) or an ubiquitous sensor network (USN) system.

Nowadays, ubiquitous network technology is attracting attention of many people. Ubiquitous network technology means a technology that makes it possible to connect to various networks smoothly regardless of time and place.

Examples of such ubiquitous network technology include RFID or USN technology, and among them, RFID technology introduced in commerce is representative.

Ubiquitous Senser Network (USN) refers to a network system configured to wirelessly collect information collected from various sensors. For example, hundreds of sensor network nodes are installed in vulnerable areas that are inaccessible to humans. It can play the same role as monitoring.

In general, a commercial RFID system consists of an RFID tag attached to a product and embedded with details, an RFID reader that reads information of the RFID tag using RF communication, and the RFID tag attached to the product is located at which the RFID reader is located. Since information is transmitted through RF communication through the region, it provides a foundation for efficiently managing logistics / distribution such as distribution, assembly, price change, and sales of goods.

1 is a block diagram schematically showing the components of a general RFID reader 10.

Referring to FIG. 1, a general RFID reader 10 includes an antenna 11, a signal separator 12, an RF receiver 13, a baseband receiver 14, an Rx phase locked loop (PLL) 15, and a controller ( 16), the baseband transmitter 17, the Tx PLL 18, and the RF transmitter 19.

The antenna 11 has a structure for transmitting or receiving a transmission and reception signal together, and the signal separation unit 12 separates the transmission signal and the reception signal and transfers the transmission signal to the antenna 11 or transmits the reception signal to the RF reception unit 13. It can be implemented as a device such as a circulator.

The RF receiver 13 performs low noise amplification and filtering on the high frequency signal received through the antenna 11, and the RF transmitter 19 filters the signal transmitted from the baseband transmitter 17 and amplifies the signal to a transmittable size. Let's do it.

In addition, the baseband receiver 14 receives the reference frequency signal from the Rx PLL 15 and converts the RF received signal into a baseband signal, and the baseband transmitter 17 receives the reference frequency signal from the Tx PLL 18. The baseband signal received from the control unit 16 is converted into an RF transmission signal.

At this time, the baseband signal is processed as a signal having phase angles of 0 °, 90 °, 180 °, and 270 °, that is, I (In-phase) ⁺ signal, I ^- signal, Q (Quadrature) ⁺ signal, and Q ^- signal. This is to minimize the error rate and improve the data recognition rate by processing the individual signals by changing the phase angle of the signal.

FIG. 2 is a diagram illustrating an example in which a radio wave reception angle is changed when a general RFID reader 10 communicates with a tag 20.

According to FIG. 2, when the tag 20 enters the propagation region L of the antenna 11 provided in the RFID reader 10, the RFID system 10 transmits an information request signal, and the tag 20 transmits an information request signal. Send tag information accordingly.

In general, the antenna has an inherent polarization (meaning the polarization direction of the electric field with respect to the traveling direction of the electromagnetic wave) according to the shape and operation characteristics. For example, signal polarization becomes impossible when the polarization direction is orthogonal.

For example, in FIG. 2, when the tag 20 is rotated at a predetermined angle (Yθ and Zθ) with respect to the Y axis or the Z axis, a change in phase of the signal occurs (a form in which the tag and the reader face each other based on the X axis). Is the most advantageous form for the propagation environment.

In this case, in order to improve the recognition rate of the signal, as described above, a baseband signal phase-corrected by the I ⁺ signal, the I ^- signal, the Q ⁺ signal, and the Q ^- signal is used. As a possibility, there is a limit to preventing bit errors generated during phase correction.

According to the present invention, a phase compensation system (RFID / USN system) capable of various phase corrections, effective prevention of bit errors, and improved data recognition rate can be achieved, compared to conventional I ⁺ signals, I ^- signals, Q ⁺ signals, and Q ^- signal systems. ).

The present invention compensates the reflection estimate at the speed that the echo cancellation circuit (phase synchronization circuit) can converge on the change of the echo signal appearing during phase correction, and a phase compensation system (RFID or USN system) capable of various phase corrections through a simple circuit. ).

Phase compensation system according to the present invention comprises a phase synchronization circuit for generating an oscillation frequency signal; A phase adjuster for converting a phase of the oscillation frequency signal into a plurality of oscillation frequency signals having differentiated phases; A signal converter which converts the phase-converted oscillation frequency signal into an RF signal and converts it into an intermediate frequency signal; And a controller configured to transmit a control signal having a predetermined voltage level to control the phase shift operation of the phase adjuster.

Hereinafter, a phase compensation system according to an embodiment of the present invention will be described with reference to the accompanying drawings. The phase compensation system is an RFID reader communicating with a tag. Of course, the phase compensation system according to the present invention can be utilized as a leader of the USN system.

3 is a block diagram schematically illustrating the components of the phase compensation system 100 according to an embodiment of the present invention.

Referring to FIG. 3, a phase compensation system 100 according to an exemplary embodiment of the present invention includes a first antenna 105, a first filter 110, a low noise amplifier (LNA) 115, and a balloon. The circuit 117, the first signal converter 120, the second filter 125, the third filter 127, the first phase synchronizer circuit 130, the first phase adjuster 140, and the first power amplifier ( A power amplifier (PA) 150, a second power amplifier 152, a demodulator 154, a controller 160, a modulator 165, a third power amplifier 170, a fourth power amplifier 172, Fourth filter 174, fifth filter 176, second signal converter 180, second phase synchronization circuit 200, second phase adjuster 210, power amplifier module (PAM) 190, a sixth filter 192, and a second antenna 194.

The RF signal received through the first antenna 105 from the tag is filtered by only the signal of the corresponding band by the first filter (which may be provided as a SAW filter) 110, the low noise amplifier 115 ) Amplifies the lower power RF signal due to attenuation and noise.

The low noise amplifier 115 is designed by grabbing the operating point and the matching point so that the noise figure has a small value and amplifies the RF signal while suppressing the noise component as much as possible.

The balloon circuit 117 separates the signal transmitted from the low noise amplifier 115 into an I signal (eg, "E sin ωt") and a Q signal (eg "E cos ωt"), i. The signal is converted and output.

Here, "Balun" is an abbreviation of "Balance-Unbalance", and means a circuit for converting a balanced signal into an unbalanced signal (or vice versa).

The output terminal of the balloon circuit 117 is connected to the first mixer 122 and the second mixer 124 of the first signal converter 120, and the mixers 122 and 124 are dual mixers. The mixer 122 synthesizes I intermediate frequency signals having a plurality of phases (in the past, synthesized only with I ⁺ and I ⁻ signals), and the second mixer 124 combines Q intermediate frequency signals having a plurality of phases. Synthesize (previously, synthesized only with Q ⁺ and Q ⁻ signals).

In this case, the first phase synchronization circuit unit 130 provides an oscillation frequency signal, and the first phase adjustment unit 140 generates a plurality of oscillation frequency signals shifted in phase by changing the phase of the provided oscillation frequency signal.

The first phase adjuster 140 transmits a plurality of phase shifted oscillation frequency signals to the first signal converter 120, and the first mixer 122 and the second mixer of the first signal converter 120. 124 may synthesize a plurality of phase-corrected I and Q intermediate frequency signals using the oscillation frequency signals.

The functions of the first phase synchronizing circuit unit 130 and the first phase adjusting unit 140 may be equally applied to the second phase synchronizing circuit unit 200 and the second phase adjusting unit 210. A detailed description will be made with reference to FIG. 5. For convenience of description, the description will be made only with respect to the reception path stage, that is, the first phase synchronization circuit unit 130 and the first phase adjustment unit 140.

The second filter 125 and the third filter (each of which may be provided as a "LPF; Low Pass Filter") 127 filter the phase-corrected I intermediate frequency signal and the Q intermediate frequency signal, respectively.

The first power amplifier 150 and the second power amplifier 152 amplify the phase-corrected I intermediate frequency signal and the Q intermediate frequency signal to a magnitude that can be processed in the intermediate frequency band, respectively, and the demodulator 154 performs the first power amplifier. The I and Q signals transmitted from the signal converter 120 are demodulated into digital signals having a plurality of polarities. The digitally processed signal is transmitted to the controller 160.

The controller 160 has a communication protocol to control wireless communication with the tag, and processes the signal transmitted from the demodulator 154 as a digital signal on the application layer or transfers the processed digital signal to the modulator 165. do.

The controller 160 analyzes the code of the device identification information received from the tag. At this time, the controller 160 processes a filtering operation to convert the data format and extract necessary information. The controller 160 may be implemented using a field programmable gate array (FPGA) circuit or a digital signal processing (DSP) circuit.

The modulator 165 processes the digital signal into an analog signal (intermediate frequency signal), and the third power amplifier 170 and the fourth power amplifier 172 amplify the analog processed signal.

The fourth filter 174 and the fifth filter (which may be provided as a saw filter) 176 remove signals of undesired components that are mixed during amplification, and output a plurality of I intermediate frequencies and Q intermediate frequencies, respectively. The third signal is transferred to the third mixer 182 and the fourth mixer 184 of the second signal converter 180.

The third mixer 182 and the fourth mixer 184 are dual mixers. The third mixer 182 converts a plurality of I intermediate frequency signals into an I RF signal, and the fourth mixer 184 includes a plurality of Q's. The intermediate frequency signal is converted into a Q RF signal.

In this case, the second phase synchronization circuit unit 200 provides an oscillation frequency signal, and the second phase adjustment unit 210 generates a plurality of oscillation frequency signals shifted in phase by changing the phase of the provided oscillation frequency signal.

The second phase controller 210 transmits a plurality of phase shifted oscillation frequency signals to the second signal converter 180, and the third mixer 182 and the fourth mixer of the second signal converter 180. 184 mixes the oscillation frequency signals with a plurality of I intermediate frequency signals and Q intermediate frequency signals to convert them into RF signals.

The power amplification module 190 receives the RF signal from the second signal converter 180 and amplifies the RF signal to a size that can be transmitted, and the RF signal of the corresponding band filtered by the sixth filter 192 is the second antenna 194. Is sent through.

4 is a block diagram schematically illustrating the components of the first phase synchronization circuit unit 130 included in the phase compensation system 100 according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the first phase synchronizer circuit 130 includes a TCXO (Temperature Controlled X-tal Oscillator) 131, a frequency detector 132, a divider 136, a charge pump 133, and a loop filter (LPF). 134, a voltage controlled oscillator (VCO) 135, and the VCO 135 includes a power supply 135b and a resonator 135a.

The TCXO 131 is a device for controlling the frequency disturbance according to the temperature change generated in the crystal oscillator. The TCXO 131 provides the frequency detector 132 with a reference frequency signal having a frequency of a constant value with respect to the temperature change.

The frequency detector 132 receives the reference frequency signal and detects and compares the oscillation frequency signal output from the VCO 135.

In general, since the oscillation frequency signal provided from the VCO 135 is a high frequency signal and the reference frequency signal provided from the TCXO 131 is a low frequency signal, the divider 136 uses the detected oscillation frequency signal at a low frequency so that the two signals can be compared. The signal is converted into a band and transmitted to the frequency detector 132.

The frequency detector 132 compares the two signals and transmits a control signal corresponding to the frequency difference to the charge pump 133, and the charge pump 133 adjusts the current value according to the control signal.

The charge pump 133 supplies a specific amount of charge to the loop filter 134 by a branch circuit if the voltage of the oscillation frequency signal is larger than that of the reference frequency signal, and charges the loop filter (if the voltage of the oscillation frequency signal is small). 134).

The loop filter 134 may be configured as, for example, a secondary filter including two capacitors and one resistor, and adjusts the voltage of the VCO 135 in response to the amount of charge pushed and pulled by the charge pump 133.

The power supply unit 135b supplies power and the resonator unit 135a may adjust the voltage by the loop filter 134 to provide a stable oscillation frequency signal.

5 is a circuit diagram schematically illustrating the components of the first phase adjuster 140 included in the phase compensation system 100 according to an exemplary embodiment of the present invention.

As described above, the first phase adjusting unit 140 converts the phase of the oscillation frequency signal into a plurality of oscillation frequency signals having different phases. Referring to FIG. 5, the transformer 141 and the diode unit 142 and filter units 143 and 144.

The controller 160 sequentially transmits control signals having differentiated voltages so that the first phase adjuster 140 can vary the phase of the oscillation frequency signal, and the transformer 141 feeds back according to the control signal. The phase of the oscillation frequency signal is changed by performing a frequency adjustment operation according to the current.

According to the transformer 141, the phase of the oscillation frequency signal can be achieved by various phase shift mainly by repeating the inversion (inverted to the reverse phase signal of the same amplitude).

The input terminal "A" of the transformer 141 is connected to the VCO 135 of the first phase synchronization circuit unit 130, and the output terminal "B" is the first mixer 122 and the first signal of the first signal conversion unit 120. 2 mixer 124 is connected.

The diode unit 142 includes two diodes 142a and 142b, wherein the first diode 142a and the second diode 142b are connected to the first coil end and the second coil end of the transformer 141, respectively. And are connected to face each other.

The input terminal of the first diode 142a is connected to the control signal input terminal C through the first resistor 142c, and the input terminal of the second diode 142b is connected to the control signal input terminal C through the second resistor 142d. ).

For example, when a voltage of about 2V is applied between the first diode 142a and the second diode 142b, and the voltage between the first resistor 142c and the second resistor 142d reaches about 0V or more, the diode 142a and 142b are operated to adjust the impedance of the oscillation frequency circuit (phase shift).

That is, the interval between phases that can be converted by the transformer 141 may be converted into a more precise phase angle by the diode unit 142.

The filter unit 143 and 144 includes a first capacitor 143 and a second capacitor 144 connected to the control signal input terminal, and together with the first resistor 142c and the second resistor 142d, a kind of RC filter. It performs a function and isolates and filters the AC signal included in the DC control signal.

6 is a graph measuring the phase angle of the oscillation frequency signal converted by the phase compensation system 100 according to an embodiment of the present invention.

In the graph shown in FIG. 6, the x-axis represents a frequency axis of the GHz band, and the y-axis represents a phase angle shifted according to the control signal. When the control signal d1 of about 0 V is applied in the 900 MHz frequency band, the phase shift is If the control signal d2 of about 4V is applied without phase, a phase shift of about 50 degrees occurs.

In addition, it can be seen that a phase shift of about 100 degrees occurs when the control signal d3 of about 8V is applied, and a phase shift of about 110 degrees occurs when the control signal d4 of about 12V is applied.

7 is a circuit diagram schematically illustrating components of the first signal converter 120 included in the phase compensation system 100 according to an exemplary embodiment of the present invention.

The first mixer 122 and the second mixer 124 of the first signal converter 120 have an oscillation frequency signal LO I ⁺ signal that is phase-shifted from the output terminals D1 and D2 of the first phase adjuster 140. LO I ^- signal, LO Q ⁺ signal, LO Q ^- signal) is transmitted, synthesized with the RF + signal and the RF- signal transmitted from the balloon circuit 117 (E1, E2), respectively IF I ⁺ signal, IF I ^The signal is converted into a signal, an IF Q ⁺ signal, and an IF Q ⁻ signal and output to the second filter stages F1 and F2 and the third filter stages G1 and G2.

FIG. 8 is a graph illustrating various phase conversions of intermediate frequency signals on a phase compensation system 100 according to an exemplary embodiment of the present invention, and FIG. 9 is a phase compensation system 100 according to an exemplary embodiment of the present invention. It is a graph showing a form in which the phase of the intermediate frequency signal is variously converted in phase.

Referring to FIG. 8, it can be seen that an oscillation frequency signal having various phases is generated by the first phase synchronization circuit unit 130, the first phase adjustment unit 140, and the first signal conversion unit 120. The section between 0 degrees, 90 degrees, 180 degrees, and 270 degrees is further divided into transitions with various phase angles.

In FIG. 8, the region "H1" means the region of the I signal (for example, "E sin? T"), and the region "H2" means the region of the Q signal (for example "E cos? T").

In addition, according to FIG. 9, an intermediate frequency signal, that is, an IF I ⁺ signal f1, an IF I ⁻ signal f2, and an IF Q ⁺ signal g1 according to an oscillation frequency signal converted to various phases as shown in FIG. 8. ), The result of synthesizing the IF Q ⁻ signal g2 by the first signal converter 120 is measured on the left side, and the current flow I in the case where these signals are mixed and transmitted is measured on the right side. .

Therefore, according to the phase compensation system 100 according to the present invention, since the intermediate frequency signal having various phases can be generated so as to cope with the change in the echo signal, the echo estimation value is generated at a speed that can stably analyze the signal. Can compensate.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications not illustrated in the drawings are possible. For example, each component specifically shown in the embodiments of the present invention can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

According to the RIFD or USN system to which the phase compensation system or the phase compensation system according to the present invention is applied, various phase corrections can be performed, and bit errors generated during phase correction can be effectively prevented.

In addition, according to the present invention, it is possible to improve the data recognition rate through a simple circuit configuration, and there is an effect that can provide an RFID or USN system that performs low-cost and high-speed stable communication because no additional device is required. .

Claims (6)

A phase synchronization circuit unit generating an oscillation frequency signal; A phase adjuster for converting a phase of the oscillation frequency signal into a plurality of oscillation frequency signals having differentiated phases; A signal converter which converts the phase-converted oscillation frequency signal into an RF signal and converts it into an intermediate frequency signal; And It includes a control unit for transmitting a control signal having a predetermined voltage level to control the phase shift operation of the phase adjuster, The phase adjuster includes a transformer connected to the phase synchronization circuit unit and receiving the oscillation frequency signal and transmitting the phase shifted oscillation frequency signal to a signal converter. The method of claim 1, wherein the phase adjustment unit And a diode connected between the coil end of the transformer and the input end of the control signal. The method of claim 2, wherein the phase adjustment unit And a filter unit connected between the diode and an input terminal of the control signal and including at least one of a capacitor and a resistor. The method of claim 1, wherein the signal conversion unit A phase compensation system comprising at least two mixers. The method of claim 1, And a demodulator configured to receive the intermediate frequency signal from the signal converter and demodulate the digital signal having a plurality of polarities. The system of claim 1, wherein the phase compensation system is A phase compensation system, characterized in that the RFID (Radio Frequency IDentification) reader or USN (Ubiquitous Sensor Network).

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