JP7212473B2 - Receiver and receiving method using pulse - Google Patents

Description

The present invention relates to a receiver and receiving method using pulses.

Recently, with the development of information and communication technology, IoT (Internet of Things) devices that attach sensors to things and exchange data in real time have become widespread. As ultra-compact wireless transceivers, IoT devices exchange and process information between distributed components such as things by communicating at low power. In order to implement an ultra-compact and low-power communication system for IoT devices, wireless communication should be performed with excellent reception sensitivity and low power despite response delay.

Japanese Patent Application Laid-Open No. 2007-201626

SUMMARY OF THE INVENTION An object of the present invention is to provide a receiver and a receiving method using pulses.

A receiver according to one aspect of the present invention, which has been made to achieve the above object, includes an antenna for receiving a radio signal, a pulse generator for generating a pulse, and a receiver driven based on the pulse and based on the radio signal. An oscillator that generates an oscillating signal, and a measuring unit that is driven based on the pulse and measures the degree of oscillation of the oscillating signal, wherein the radio signal is received based on the degree of oscillation of the oscillating signal.

The measurement unit may measure an oscillation time of the oscillation signal as an oscillation degree of the oscillation signal, and the wireless signal may be received based on the oscillation time of the oscillation signal measured by the measurement unit.
The measuring unit may generate an output proportional to the oscillation time of the oscillating signal, and the wireless signal may be received based on whether the generated output exceeds a predetermined threshold.
The radio signal is received as a first value when the oscillation time of the oscillation signal is longer than a predetermined critical time, and is received as the first value when the oscillation time of the oscillation signal is shorter than the predetermined critical time. It may be received as a second value different from the one value.
Based on the oscillation time of the oscillating signal, the amplitude or frequency of the radio signal received by the antenna can be received.
The receiver provides a first current to the oscillator during a first interval from the beginning of the pulse to the midpoint of the pulse, and a second interval from the midpoint of the pulse to the end of the pulse. and a current supplier for providing a second current smaller than the first current to the oscillator between obtain.
The receiver further comprises two capacitors applied to the oscillator, the two capacitors being mismatched with each other during a first interval from the beginning of the pulse to the middle of the pulse, and A second time interval from an intermediate time point to an end time point of the pulse is matched with each other, and the intermediate time point of the pulse may be between the start time of the pulse and the end time of the pulse.
The receiver may further include an inductor applied to the oscillator, the inductor having a Q-value greater than a threshold.
The measuring section may generate an output proportional to the oscillation time of the oscillating signal, and the pulse generator may adjust the pulse width of the pulse based on the output generated by the measuring section.
The measurement unit may generate an output proportional to the oscillation frequency of the oscillation signal and the pulse width of the pulse based on the oscillation time of the oscillation signal.
The pulse generator may generate the pulses with a period smaller than half the OOK (On-Off Keying) modulation period of the radio signal.
The measuring unit may detect an envelope of the oscillation signal as an oscillation degree of the oscillation signal, and the wireless signal may be received based on the detected envelope.
The measuring unit may measure the amplitude of the detected envelope, and the wireless signal may be received based on whether the amplitude of the detected envelope exceeds a threshold.
The oscillator and the measuring unit may operate during intervals during which the oscillator and the measuring unit receive the pulses from the pulse generator.
The power consumption of the receiver may be determined by the data rate of the radio signal and the pulse width of the pulses.
The receiver may further include an RF amplifier that is driven based on the pulse, amplifies the oscillation signal, and outputs the amplified oscillation signal to the measurement unit.

A reception method according to one aspect of the present invention, which has been made to achieve the above object, comprises the steps of generating a pulse at a predetermined period; generating an oscillation signal based on a radio signal received by an antenna during the pulse; and measuring the degree of oscillation of the oscillating signal during the pulses, wherein the steps of generating the oscillating signal and measuring the degree of oscillation are activated based on the pulses. and the radio signal is received based on the degree of oscillation of the oscillating signal.

A receiver according to another aspect of the present invention, which has been made to achieve the above object, comprises an antenna for receiving a radio signal, a pulse generator for generating a pulse in a predetermined period interval, and an oscillator driven based on said radio signal to generate an oscillating signal based on said pulse only during the presence of said pulse; and said oscillator driven based on said pulse and dependent on said radio signal only during said pulse. a measuring unit that measures the degree of oscillation of the oscillation signal, wherein the radio signal is received based on the degree of oscillation of the oscillation signal.

According to the receiver and reception method using pulses of the present invention, wireless communication with low power consumption, no response delay, and excellent reception sensitivity can be performed. Also, the power consumption of the receiver can be minimized by minimizing the active period according to the extremely short pulse. Also, average power consumption can be minimized by powering on the receiver with a period less than half the OOK modulation period of the radio signal.

Fig. 3 shows a receiver according to one embodiment; FIG. 4 illustrates a receiver with TDC applied according to one embodiment; FIG. 4 is a diagram illustrating a process of receiving a wireless signal in a receiver to which a TDC is applied according to one embodiment; FIG. 4 is a diagram illustrating a process of receiving a wireless signal in a receiver to which a TDC is applied according to one embodiment; FIG. 4 is a diagram illustrating a process of receiving a wireless signal in a receiver to which a TDC is applied according to one embodiment; FIG. 4 is a diagram illustrating a process of receiving a wireless signal in a receiver to which a TDC is applied according to one embodiment; FIG. 3 is a circuit diagram of a receiver with a TDC applied according to one embodiment; 8 is a diagram showing a process of receiving a radio signal by the receiver shown in FIG. 7; FIG. FIG. 4 is a diagram for explaining a process of generating a TDC output based on a radio signal according to one embodiment; FIG. 4 is a diagram illustrating an output of a TDC that is not affected by jitter of a clock generator according to one embodiment; FIG. 10 is a diagram illustrating TDC output variation with pulse width according to one embodiment; FIG. 4 is a diagram for explaining fast start-up of a receiver according to one embodiment; FIG. 4 is a diagram for explaining fast start-up of a receiver according to one embodiment; FIG. 4 is a circuit diagram of a receiver to which a pulse width controller is applied according to one embodiment; FIG. 4 is a diagram for explaining power consumption of a receiver according to one embodiment; FIG. 4 is a diagram for explaining a receiver to which ED is applied according to an embodiment; FIG. 4 is a diagram for explaining a receiver to which ED is applied according to an embodiment; 4 is a flowchart illustrating a receiving method according to one embodiment; 4 is a flow chart illustrating a method of controlling the width of pulses generated by a pulse generator according to one embodiment.

Specific structural or functional descriptions of the embodiments herein may be varied in various ways, as disclosed for the purpose of illustration only. Accordingly, the embodiments are not limited to the particular disclosed forms, and the scope of the specification includes modifications, equivalents, or alternatives falling within the scope of the technical spirit.

Although terms such as first or second may be used to describe multiple components, such terms should be construed only for the purpose of distinguishing one component from another. For example, a first component can be named a second component, and similarly a second component can be named a first component.

Singular expressions include plural expressions unless the context clearly dictates otherwise. As used herein, the terms "including" or "having" indicate the presence of the features, numbers, steps, acts, components, parts, or combinations thereof described in the specification. without excluding the possibility of the presence or addition of one or more other features, figures, steps, acts, components, parts, or combinations thereof.

Unless otherwise defined, all terms, including technical or scientific terms, used herein are to be commonly understood by one of ordinary skill in the art to which the embodiments belong. have the same meaning. Commonly used pre-defined terms are to be construed to have a meaning consistent with the meaning they have in the context of the relevant art, and unless expressly defined herein, are ideally or excessively It is not to be interpreted in a formal sense.

Hereinafter, specific examples of embodiments for carrying out the present invention will be described in detail with reference to the drawings. Identical reference numerals appearing in the drawings indicate identical elements.

FIG. 1 illustrates a receiver according to one embodiment.

Referring to FIG. 1, the receiver 100 according to this embodiment includes an antenna 110, a pulse generator 120, an oscillator 130, and a measuring section 140. FIG.

The receiver 100 is a device that receives a radio signal, for example, a low-power communication device, an IoT (Internet of things) device, an in-vivo communication device, a microminiature wireless transceiver such as a MICS (Medical Implant Communications System) device. embodied.

A radio signal is input to the antenna 110 . A radio signal is, for example, an RF signal (radio frequency signal) as a signal transmitted and received via radio communication. The RF signal may be a signal modulated by ASK (Amplitude Shift Keying), for example, a signal modulated by OOK (On-Off Keying). Alternatively, the RF signal is a signal modulated by FSK (Frequency Shift Keying). For convenience of explanation, the following description will be based on the case where the radio signal is modulated by OOK.

A pulse generator 120 generates pulses. A pulse generator 120 generates pulses according to a predetermined period. For example, the predetermined period is less than half the OOK modulation period of the radio signal. A pulse generated by the pulse generator 120 is provided to the oscillator 130 and the measuring unit 140 .

The oscillator 130 is an LC-VCO (Inductor Capacitor-Voltage Controlled Oscillator) driven by pulses. For example, since the oscillator 130 is not driven during a period in which no pulses are provided to the oscillator 130, the oscillator 130 does not generate an oscillating signal. Conversely, the oscillator 130 is driven during the period in which the pulse is provided to the oscillator 130, and an oscillating signal is generated based on the radio signal. That is, the power consumption of the receiver 100 can be efficiently reduced by driving the oscillator 130 only during a short interval in which the pulse is provided from the pulse generator 120 .

When pulses are provided to oscillator 130 , oscillator 130 generates an oscillating signal based on the radio signal input to antenna 110 . For example, the oscillation signals generated by the oscillator 130 are different depending on whether the radio signal "1" is input to the antenna 110 or the radio signal "0" is input to the antenna 110 during the period in which the pulse is provided. Oscillator 130 determines the presence or absence of an RF carrier and thereby generates an oscillating signal. The oscillation signal will be described later with reference to FIG.

The measurement unit 140 measures the degree of oscillation of the oscillation signal. Here, the measurement unit 140 is also driven by pulses. That is, it measures the degree of oscillation of the oscillation signal driven during the interval in which the pulse is provided from the pulse generator 120 . The measurement unit 140 measures the oscillation time of the oscillation signal or the envelope of the oscillation signal as the degree of oscillation of the oscillation signal. Specifically, as will be described later, when measuring the oscillation time of the oscillation signal as the degree of oscillation of the oscillation signal, the measurement unit 140 counts the oscillation signal and outputs the count number to determine the degree of oscillation of the oscillation signal. When measuring the envelope of a signal, the envelope is detected when the oscillation signal rises.

A radio signal is received based on the degree of oscillation of the oscillation signal measured by the measuring unit 140 . For example, the radio signal is received based on the oscillation time of the oscillation signal measured by the measurement unit 140 . Alternatively, the radio signal is received based on the envelope of the oscillation signal measured by measuring section 140 .

For convenience of explanation, a case where a radio signal is received based on the oscillation time of the oscillating signal will be described below, and a case where the radio signal is received based on the envelope of the oscillating signal will be described with reference to FIG. will be described later.

FIG. 2 illustrates a receiver with a TDC according to one embodiment.

Referring to FIG. 2, the receiver 200 according to this embodiment includes an antenna 210, a clock generator 220, a pulse generator 230, an oscillator 240, and a TDC (Time-to-Digital Converter) 250. FIG. The measurement unit 140 shown in FIG. 1 corresponds to the TDC 250 , and in this case, the receiver 200 receives the radio signal V _RF based on the oscillation time of the oscillation signal V _OSC measured by the TDC 250 .

A radio signal V _RF is input to antenna 210 . For example, the radio signal _VRF is a signal modulated by OOK and has a '1' or a '0'.

Clock generator 220 generates a clock signal and provides it to pulse generator 230 . A pulse generator 230 generates a pulse V _PULSE at a predetermined period based on the received clock signal. Pulse V _PULSE drives (ie, powers on) oscillator 240 and TDC 250 .

Oscillator 240 is an LC-oscillator driven by pulse V _PULSE to produce oscillating signal V _OSC based on radio signal V _RF . Oscillator 240 generates oscillation signal V _OSC that oscillates at different times according to radio signal V _RF . For example, when the radio signal V _RF input to the antenna 210 is '1', the oscillator 240 generates an oscillating signal V _OSC that oscillates for a longer period of time than when the radio signal V _RF is '0'. do. On the other hand, when the radio signal V _RF input to the antenna 210 is '0', the oscillator 240 generates an oscillation signal V _OSC that oscillates for a shorter period of time than when the radio signal V _RF is '1'. do.

TDC 250 measures the oscillation time during which oscillation signal V _OSC oscillates, and outputs the measurement result to N _OUT . TDC 250 produces an output N _OUT that is proportional to the oscillation time that oscillating signal V _OSC oscillates. For example, TDC 250 uses the oscillation start time of oscillation signal V _OSC to generate output N _OUT . TDC 250 recognizes that oscillating signal V _OSC is oscillating and produces an output N _OUT when the amplitude of oscillating signal V _OSC exceeds a predetermined threshold amplitude.

Receiver 200 receives radio signal V _RF based on TDC 250 output N _OUT . For example, if the output N _OUT of TDC 250 is greater than a predetermined threshold number, receiver 200 receives wireless signal V _RF as "1". Alternatively, if the output N _OUT of TDC 250 is less than or equal to a predetermined threshold number, receiver 200 receives wireless signal V _RF as '0'.

3 to 6 are diagrams illustrating a process of receiving wireless signals in a receiver to which a TDC is applied according to an embodiment.

FIG. 3 shows the radio signal V _RF , the pulse V _PULSE and the received signal V _OUT according to this embodiment.

The radio signal _VRF has "1" or "0" as the signal modulated by OOK. The OOK modulation period of the radio signal _VRF is 1/ _fS . The pulse V _PULSE is generated with a period less than or equal to 1/2 times the OOK modulation period 1/f _S of the radio signal V _RF .

The received signal V _OUT has a value obtained by receiving the radio signal V _RF during the interval in which the pulse V _PULSE is provided. In the exemplary illustration of FIG. 3, the received signal V _OUT also has a "1" due to the fact that the radio signal V _RF has a "1" when the first, second, fifth and sixth pulses are provided. However, since the radio signal _{V_RF} has a '0' when the third and fourth pulses are provided, the received signal _{V_OUT} also has a '0'.

Thus, the receiver operates based on the pulse V _PULSE and measures the oscillation time of the oscillation signal using the TDC, thereby accurately receiving the radio signal V _RF even in a short pulse period.

FIG. 4 shows the case where the radio signal V _RF has a "1". Here, pulse V _PULSE is high during T _PULSE .

If the radio signal _{V_RF} has a value of '1' during the period in which the pulse _{V_PULSE} is provided, the oscillator quickly generates the oscillation signal _{V_OSC} . That is, the oscillating signal _VOSC oscillates from the point of time approaching the rising edge of the pulse V _PULSE . As the oscillating signal _VOSC oscillates quickly, the section in which the amplitude of the oscillating signal _VOSC increases beyond a predetermined level also becomes longer.

The TDC measures the length of time during which the amplitude of the oscillating signal _VOSC is greater than a predetermined magnitude. That is, the output _NOUT of the TDC is proportional to the oscillation time _t1 of the oscillation signal _VOSC . If the oscillation time t1 of the oscillation signal V _OSC is longer than _a predetermined critical time, the receiver receives the radio signal V _RF as "1". Here, the predetermined critical time corresponds to a predetermined threshold number N _REF , and if the output N _OUT of the TDC is greater than the predetermined threshold number N _REF , the oscillation time t of the oscillation signal V _{OSC 1} is determined to be longer than a predetermined critical time.

Here, the more similar the frequency _fRF of the radio signal _VRF and the oscillation frequency _fOSC of the oscillation signal _VOSC are to each other, the greater the influence of the radio signal _VRF on the oscillation signal _VOSC . The oscillation signal _VOSC oscillates rapidly in response to the _VRF . Conversely, when the frequency f _RF of the radio signal V _RF and the oscillation frequency f _OSC of the oscillation signal V _OSC are not similar to each other, the influence of the radio signal V _RF transmitted to the oscillation signal V _OSC is small, and the radio Oscillating signal _VOSC does not oscillate quickly in response to signal _VRF . Based on this principle, by making the frequency f _RF of the radio signal V _RF and the oscillation frequency f _OSC of the oscillation signal V _OSC similar to each other, the oscillation time of the oscillation signal V _OSC is determined according to the presence or absence of the radio signal V _RF . , and the presence or absence of the radio signal V _RF is detected with high accuracy based on the oscillation time of the oscillation signal V _OSC .

FIG. 5 shows the case where the radio signal V _RF has a "0".

If the radio signal V _RF has a '0' at the time the pulse V _PULSE is provided, the oscillator slowly generates the oscillating signal V _OSC . That is, the oscillation signal _VOSC oscillates at a point far from the rising edge of the pulse V _PULSE . By slowly oscillating the oscillating signal _VOSC , the section in which the amplitude of the oscillating signal _VOSC is larger than a predetermined magnitude is also shortened.

Since the TDC continuously generates an output during a section in which the amplitude of the oscillation signal V _OSC is greater than a predetermined magnitude, the oscillation time _t0 of the oscillation signal V _OSC is obtained through the output N _OUT of the TDC. do. If the oscillation time _t0 of the oscillation signal V _OSC is shorter than a predetermined critical time, the receiver receives the radio signal V _RF as '0'. Here, the predetermined critical time corresponds to a predetermined threshold number N _REF , and if the output N _OUT of the TDC is less than or equal to the predetermined threshold number N _REF , the oscillating signal V _OSC is _shorter than a predetermined critical time. The oscillation time _t0 of the oscillation signal V _OSC shown in FIG. ₅ is shorter than the oscillation time t1 of the oscillation signal V _OSC shown in FIG.

FIG. 6 shows a process in which a radio signal is received based on TDC.

In step S610, the wireless signal _VRF has '1', '0', '1', '0'. The OOK modulation period of the radio signal _VRF is _TS .

At step S620, a pulse V _PULSE is generated from the pulse generator at a predetermined period. For example, the pulse V _PULSE is generated with a period less than or equal to 1/2 times the OOK modulation period T _S of the radio signal V _RF . The receiver is powered on during the period when the pulse V _PULSE is generated, and is powered OFF during the period when the pulse V _PULSE is not generated. The interval in which the pulse V _PULSE was generated is sustained during the T _PULSE .

At step S630, an oscillator driven by the pulse V _PULSE generates an oscillating signal V _OSC based on the radio signal V _RF . For example, the oscillating signal V _OSC generated in the section in which the radio signal VRF is "1" oscillates for a longer time than the oscillating signal V _OSC generated in the section in which the radio signal _VRF is "0". .

In step S640, the TDC driven by the pulse V _PULSE produces an output N _OUT proportional to the oscillation time that the oscillation signal V _OSC has oscillated. For example, the oscillation signal V _OSC generated in the section where the radio signal V _RF is '1' oscillates longer than a predetermined critical time, so that the output N _OUT of the TDC is also a predetermined threshold number N. _REF and the receiver receives the radio signal V _RF as a "1". Alternatively, the oscillation signal V _OSC generated in the section where the radio signal V _RF has '0' oscillates for a period shorter than a predetermined critical time, and the output N _OUT of the TDC is also shorter than the predetermined threshold number N _REF . becomes smaller and the receiver receives the radio signal V _RF as "0".

The TDC output N _OUT is maintained until reset by a reset signal. A reset signal is provided to the TDC to reset the output N _OUT before the next pulse V _PULSE is generated.

The threshold number N _REF may be predetermined or dynamically changed. In order to dynamically change the threshold number N _REF , for example, when the predetermined radio signal "1, 0, 1, 0" is input, the output N _OUT of the TDC is "10, 5, 10, 5". , the threshold number N _REF is set to 7.5.

FIG. 7 is a diagram illustrating a circuit diagram of a receiver to which a TDC is applied according to one embodiment.

Referring to FIG. 7, a receiver 700 according to this embodiment includes a controller 710, a receive main block (RX main block) 720, and an antenna 730. FIG. Receiver 700 is an RF transceiver.

Controller 710 generates and provides pulse V _PULSE to receive main block 720 . For example, RC-oscillator is a clock generator that generates a clock signal and provides the generated clock signal V _RC to a pulse generator. The pulse generator produces a pulse V _PULSE based on the clock signal V _RC and provides it to the oscillator, RF amplifier and TDC in receive main block 720 . Here, the pulse V _PULSE is generated with a period determined by the frequency divider, and the width of the pulse V _PULSE is determined by the pulse generator.

The fast start-up is a circuit that reduces the width of the pulse V _PULSE by causing the oscillator to generate the oscillating signal V _OSC quickly, which will be described later with reference to FIGS.

An oscillator in receive main block 720 is driven by pulse V _PULSE to generate an oscillating signal V _OSC based on the radio signal input to antenna 730 . The oscillating signal _VOSC is amplified by an RF amplifier. The RF amplifier is driven by pulse V _PULSE . Although two RF amplifiers are shown in FIG. 7 for convenience of explanation, the receive main block 720 can include one or more RF amplifiers without limitation.

The TDC outputs N _OUT proportional to the oscillation time of the amplified oscillating signal V _OSC2 driven by the pulse V _PULSE . The TDC receives a reset signal V _RST from the RST controller to reset the output N _OUT before the next pulse V _PULSE is provided.

The synchronizer phase-synchronizes the clock signal V _SAM and the output N _OUT of the TDC. The synchronized signal V _S is then compared with a predetermined threshold voltage V _REF in a comparator to output the received signal V _OUT . Here, the predetermined threshold voltage V _REF corresponds to the predetermined threshold number N _REF described above.

FIG. 8 is a diagram illustrating a process of receiving radio signals by the receiver of FIG.

FIG. 8 shows the radio signal V _RF , the pulse V _PULSE , the oscillating signal V _OSC , the amplified oscillating signals V _OSC1 , V _OSC2 , and the output N _OUT of the TDC. FIG. 8, shown as an example, shows the case where the radio signal V _RF is "1" when the pulse V _PULSE is generated.

During the interval when the pulse V _PULSE is provided to the receive main block 720 shown in FIG. 7, the receiver operates to receive the radio signal V _RF . On the other hand, during the period in which the pulse V _PULSE is not provided, the receiver does not operate and maintains the received signal. A pulse V _PULSE is provided during T _PULSE , _which is longer than the start-up time T _SET . The start-up time _{T_SET} will be described later with reference to FIG.

Oscillating signal V _OSC is generated based on radio signal V _RF with an oscillator driven by pulse V _PULSE . As an example, if the amplitude of the oscillating signal _VOSC is very small, it may be difficult for the TDC to produce a useful output. Therefore, it is necessary to amplify the oscillating signal V _OSC through one or more RF amplifiers. In FIG. 8, V _OSC1 and V _OSC2 indicate amplified oscillation signals.

_The TDC outputs N _OUT proportional to the oscillation time t1 based on the finally amplified oscillation signal V _OSC2 . For example, the TDC outputs N _OUT proportional to the oscillation time t1 by generating _an output when the amplitude of the final amplified oscillating signal V _OSC2 is greater than a predetermined threshold amplitude. The TDC's output N _OUT is maintained until a reset signal is provided.

FIG. 9 is a diagram illustrating a process of generating a TDC output based on a radio signal according to one embodiment.

FIG. 9 shows the start-up time T _SET and the driving time T _SS of TDC.

As a pulse-based carrier sensing (IBCS), the receiver is powered on during intervals when the pulse V _PULSE is generated and powered off during intervals when the pulse V _PULSE is not generated. Operate.

A width T _PULSE of the pulse V _PULSE is divided into a start-up time T _SET and a driving time T _SS of the TDC. The start-up time T _SET is the interval during which the amplitude of the oscillating signal is not greater than a predetermined threshold amplitude and no output is produced at the TDC. The drive time _TSS is the interval during which an output is generated at the TDC because the amplitude of the oscillating signal is greater than the predetermined threshold amplitude. That is, the width T _PULSE of the pulse V _PULSE is expressed as follows.

In the above equation (1), T _OSC indicates the oscillation period of the oscillator, and f _OSC indicates the oscillation frequency of the oscillator. Here, f _OSC is also referred to as the carrier frequency as the high frequency.

In equation (1), decreasing T _SET or increasing the oscillation frequency f _OSC effectively decreases the width T _PULSE of the pulse V _PULSE , thereby reducing the power consumption of the receiver.

T1 shown in FIG. 9 indicates the time measured at TDC when the radio signal _VRF is " ₁ ", and _T0 indicates the time measured at TDC when the radio signal _VRF is "0". show.

In FIG. 9, for convenience of explanation, the description was based on the case where the radio signal V _RF was modulated by OOK, but when the radio signal V _RF is modulated by ASK, the amplitude of the radio signal V _RF By allowing the TDC output N _OUT to be output from the TDC, the radio signal V _RF can be received without restriction and, if the radio signal V _RF is modulated by FSK, the frequency of the radio signal V _RF The radio signal _VRF can be received without limitation by causing the TDC to output a larger output _NOUT from the TDC as the oscillation frequencies of the oscillation signals approach each other. Also, when the radio signal _VRF is modulated by FSK, the output _NOUT of the TDC is inversely proportional to the frequency difference between the frequency of the _radio signal _VRF and the oscillation frequency of the oscillating signal. is received without restriction. That is, the smaller the frequency difference, in other words, the closer the frequency of the radio signal _VRF to the oscillation frequency of the oscillation signal, the larger the output _NOUT . Conversely, the larger the frequency difference, ie, the farther the frequency of the radio signal _VRF from the oscillation frequency of the oscillation signal, the smaller the output _NOUT .

FIG. 10 is a diagram illustrating an output of a TDC that is not affected by jitter of a clock generator according to one embodiment.

FIG. 10 shows the radio signal V _RF , the clock signal V _RC generated by the clock generator, the pulse V _PULSE generated by the pulse generator, and the output N _OUT of the TDC.

Jitter exists in the clock signal _VRC generated by the clock generator. Jitter means that the period of the clock generator that produces the clock signal _VRC varies. The oscillator produces a pulse V _PULSE on the rising edge of the clock signal V _RC and jitter shown on the rising edge can cause pulse position variation by ΔT _RC .

Due to pulse position fluctuation, position fluctuation also occurs in the output _NOUT of the TDC. Also, the timing at which the output of the TDC is _reset by the reset signal VRST also varies. However, as described above, the receiver receives the radio signal V _RF based on the output N _OUT of the TDC, so that it is not affected by jitter of the clock generator. That is, the TDC output N _OUT is only proportional to the oscillation frequency of the oscillation signal and the width of the pulse V _PULSE , and is not affected by the jitter of the clock generator. The receiver is immune to the jitter of the internal clock generator and can receive the wireless signal V _RF without being affected by the jitter.

FIG. 11 is a diagram illustrating TDC output change according to pulse width according to one embodiment.

FIG. 11 shows the pulse V _PULSE , the output N _OUT of the TDC, and the reset signal V _RST .

Reducing the width of the pulse V _PULSE to reduce receiver power consumption also reduces the output N _OUT of the TDC. However, the width of the pulse V _PULSE cannot be decreased indefinitely, and the width of the pulse V _PULSE must be maintained so that the effective output N _{OUT_effective} of the TDC capable of receiving radio signals is output from the TDC.

A minimum pulse width W _min and a minimum duty cycle D _min are determined as follows. The minimum duty cycle D _min indicates the proportion of the period during which the pulse V _PULSE is high.

In equation (2) above, _fRC denotes the frequency of the clock generator. Referring to Equation (2), it can be seen that the minimum pulse width W _min excluding the TDC driving time T _SS is proportional to the oscillator startup time T _SET .

Also, the average power consumption P _AVE of the receiver is determined as follows.

In equation (3) above, _{P_RX} denotes the power consumption of the receiver and _{T_RC} denotes the period of the clock generator. Referring to equation (3), it can be seen that the receiver's average power consumption P _AVE is approximately proportional to the oscillator start-up time T _SET . Therefore, in order to minimize the power consumption of the receiver, it is necessary to minimize the start-up time _{T_SET} . A fast start-up scheme that minimizes the start-up time _{T_SET} will be described later with reference to FIGS. 12 and 13. FIG.

12 and 13 are diagrams for explaining fast start-up of the receiver according to one embodiment.

FIG. 12 shows the pulse V _PULSE , the oscillating signal V _OSC , the base current I _{QWG_O} , the additional current I _{QWG_A} for fast start-up, the current I _QWG provided to the oscillator, and the control voltage V _{PUL_C} for capacitor mismatch, FIG. 13 shows a partial circuit diagram for fast start-up.

The start-up time T _SET is an oscillation preparation period for generating the oscillation signal V _OSC . Although the TDC does not generate an output during the corresponding preparation period, the receiver is powered on and operates even during the preparation period. Therefore, power consumption occurs. Therefore, the power consumption of the receiver can be minimized by minimizing the start-up time _{T_SET} , and the following three methods can be cited as fast start-up _methods for minimizing the start-up time T_SET.

A first fast start-up strategy is to control the current _IQWG provided to the oscillator. Basically, the base current _{IQWG_O} provided to the oscillator is constant from the starting time _ta corresponding to the rising edge of the pulse V _PULSE to the ending time _tc corresponding to the falling edge. Here, additional current _{IQWG_A} is additionally provided to the oscillator for fast start-up. An additional current _{IQWG_A} is additionally provided to the oscillator from a starting time t _a to an intermediate time t _b .

The current I _QWG provided to the oscillator by the base current I _{QWG_O} and the additional current I _{QWG_A} is the first interval from the start time t _a to the intermediate time t _b than the second interval from the intermediate time t _b to the end time t _c . greater than in the interval. By controlling the current _IQWG in this manner, the start-up time _TSET can be minimized.

A second fast start-up strategy consists in controlling multiple capacitors applied to the oscillator. Referring to FIG. 13, the receiver includes an antenna 1310, a pulse generator, a phase divider, a current supplier QWG outputting a base current I _{QWG_O} , a current supplier A-QWG outputting an additional current I _{QWG_A} , a current I _{QWG_A} It includes an adder, an oscillator, and capacitors C ₁ and C ₂ that add the base current I _{QWG_O} and the additional current I _{QWG_A} to obtain . As shown in FIG. 13, the oscillator is an LC-oscillator and two capacitors (C ₁ , C ₂ ) are applied. Two capacitors (C ₁ , C ₂ ) are connected to the differential node of the oscillator and controlled by a control voltage V _{PUL_C} , expressed in the equation below.

Since the overall values of the two capacitors are constant, the oscillation frequency of the oscillator is constant. Also, by controlling the two capacitors having the k value (variable value of the variable capacitor) represented by the above equation (4) via the control voltage V _{PUL_C} , the two capacitors (C ₁ , C ₂ ) Controls whether or not there is matching between

By controlling the control voltage V _{PUL_C} , k has a value other than 1 (for example, k=1.8 to 2.0) from the start time t _a to the middle time t _b , and during the corresponding interval are controlled so that the two capacitors are mismatched with each other (that is, the capacitance values of the two capacitors are different). In addition, by controlling the control voltage V _{PUL_C} , k from the middle time t _b to the end time t _c is 1, and the two capacitors match each other (i.e., 2 control so that the capacitance values of the two capacitors are the same). That is, the two capacitors are made asymmetric from the start time t _a to the middle time t _b and symmetric from the middle time t _b to the end time t _c to minimize the start-up time T _SET .

Finally, a third fast start-up scheme is to make the inductor applied to the oscillator have a Q-value greater than a predetermined threshold. The oscillator according to one embodiment is applied as an LC-oscillator and the antenna 1310 as an inductor.

The start-up time _{T_SET} is shown below.

In equation ( ₅ ) above, gm denotes the transconductance of the core transistor of the oscillator, _w0 denotes the oscillation frequency of the oscillator, and _RT denotes the output resistance of the oscillator. Here, R _T is proportional to the square of the Q factor. Therefore, as the inductor applied to the oscillator has a larger Q value, the start-up time _{T_SET} decreases in proportion to √(1/Q).

Although FIG. 12 shows the intermediate time _tb as indicating the boundary time between the start-up time _TSET and the TDC drive time _TSS , this is for the sake of explanation only. The time tb can indicate any time between the start time t _a and the end time t _c (for example, the time when the interval from the start time t _a to the end time t _c is divided in half ₎ .

FIG. 14 is a circuit diagram of a receiver to which a pulse width controller is applied according to one embodiment.

Referring to FIG. 14, the receiver 1400 according to this embodiment includes a controller 1410, a receiving main block 1420 and an antenna 1430. Receiver 1400 is an RF transceiver.

Controller 1410 generates and provides pulse V _PULSE to receive main block 1420 . For example, the controller 1410 includes a clock generator that has a low power RC-oscillator and a main RC-oscillator that have different oscillation frequencies. A low-power RC-oscillator is a clock generator that produces a clock signal at a lower frequency than the main RC-oscillator, such that when a low-power RC-oscillator is used, the pulse generator produces long period pulses V _PULSE . Therefore, receiver 1400 consumes less power than if the main RC-oscillator were used. In FIG. 14, clock signal V _RC1 represents the signal generated by the low power RC-oscillator and clock signal V _RC2 represents the signal generated by the main RC-oscillator.

Controller 1410 selects one of the low power RC-oscillator and the main RC-oscillator based on the frequency of the radio signal input to antenna 1430 . Any one of the low-power RC-oscillator and the main RC-oscillator is selected that is capable of generating a clock signal at a frequency that is at least twice the frequency of the radio signal. If both the low power RC-oscillator and the main RC-oscillator have frequencies that are more than twice the frequency of the radio signal, the low power RC-oscillator is selected and the power consumption of the receiver 1400 is less.

A current supplier provides current I _QWG to the oscillator and includes the QWG and A-QWG shown in FIG. Also, the fast start-up circuit generates a control voltage V _{PUL_C} for capacitor mismatch and corresponds to the phase divider shown in FIG. CAP Bank indicates a plurality of capacitors applied to the oscillator, and corresponds to the _two capacitors (C1, _C2 ) shown in FIG.

The pulse width controller controls the width of the pulse V _PULSE generated by the oscillator. The pulse width controller controls the width of the pulse V _PULSE based on the output N _OUT of the TDC. The wider the pulse V _PULSE , the more time the receiver 1400 will operate, and the more power consumed by the receiver 1400 . Therefore, minimizing the width of the pulse V _PULSE minimizes the power consumption of the receiver 1400 . However, if the width of the pulse V _PULSE is made too small, the TDC may not produce an effective output _. There is a need to.

For example, a predetermined radio signal (eg, “1, 0, 1, 0”, etc.) is input to antenna 1430 for pulse width adjustment. Here, considering the output N _OUT of the TDC, the pulse width controller minimizes the width of the pulse V _PULSE within a range in which a predetermined radio signal is validly received.

Since the items described above with reference to FIGS. 1 to 13 are applied to each element shown in FIG. 14, a more detailed description will be omitted.

FIG. 15 is a diagram for explaining power consumption of a receiver according to one embodiment.

FIG. 15 shows the case where the data rate and pulse width are controlled which affects the power consumption of the receiver.

Data rate affects receiver power consumption. A first case 1510 and a second case 1520 shown in FIG. 15 show examples of receiving wireless signals having different data rates. Since the period of the pulses must be less than or equal to 1/2 times the OOK modulation period of the radio signal, the receiver is powered on and operated more frequently in the first case 1510 than in the second case 1520. There must be. Therefore, the receiver consumes less power in the second case 1520 than in the first case 1510 . That is, the lower the data rate of the radio signal, the lower the power consumption of the receiver.

Also, the pulse width affects the power consumption of the receiver. A third case 1530 and a fourth case 1540 shown in FIG. 15 show examples for different pulse widths. Since the receiver is powered on while the pulse is high, power consumption of the receiver increases in proportion to the pulse width. Therefore, the fourth case 1540 consumes less power in the receiver than the third case 1530 . That is, the smaller the pulse width, the less the power consumption of the receiver.

16 and 17 are diagrams for explaining a receiver to which ED is applied according to an embodiment.

Referring to FIG. 16, a receiver 1600 according to this embodiment includes an antenna 1610, a clock generator 1620, a pulse generator 1630, an oscillator 1640, an ED (Envelope Detector) 1650, an RF amplifier 1660, and an ADC (Analog-to-Digital Converter) 1670. The measurement unit 140 shown in FIG. 1 corresponds to the ED 1650, and in this case the receiver 1600 receives the radio signal V _RF based on the envelope V _ED of the oscillation signal V _OSC detected using the ED 1650. FIG.

A radio signal V _RF is input to antenna 1610 . Clock generator 1620 generates and provides a clock signal to pulse generator 1630 . A pulse generator 1630 generates a pulse V _PULSE with a predetermined period based on the received clock signal. Oscillator 1640 is an LC-oscillator driven by pulse V _PULSE to produce oscillating signal V _OSC based on radio signal V _RF .

Since the antenna 1610, the clock generator 1620, the pulse generator 1630, and the oscillator 1640 apply the items described above with reference to FIGS.

ED 1650 detects the envelope V _ED of the oscillating signal V _OSC . The detected envelope V _ED is amplified via RF amplifier 1660 . In FIG. 16, the amplified envelope is illustrated as V _ED1 . Although one RF amplifier is shown in FIG. 16 for convenience of explanation, one or more RF amplifiers are applicable without limitation.

ADC 1670 converts the analog form of the envelope V _ED to a digital signal. A radio signal V _RF is received by comparing the digital signal converted by ADC 1670 with a predetermined threshold. If the digital signal is greater than the predetermined threshold, the corresponding wireless signal _VRF is received as "1", and conversely if the digital signal is less than the predetermined threshold, the corresponding wireless signal VRF is received as "0". ” is received as In FIG. 16, the received signal is output as V _OUT .

FIG. 17 shows the radio signal V _RF , the pulse V _PULSE , the envelope signal V _ED , the amplified envelope signal V _ED1 , and the received signal V _OUT .

The pulse V _PULSE is generated at a frequency more than twice the radio signal V _RF frequency. When the pulse V _PULSE is high, the oscillator produces an oscillating signal and the envelope signal V _ED for the oscillating signal is detected. The envelope signal V _ED is amplified through an RF amplifier and the amplitude of the amplified envelope signal V _ED1 is compared with a predetermined threshold amplitude to output the received signal V _OUT .

FIG. 18 is a flowchart illustrating a receiving method according to one embodiment.

FIG. 18 shows the reception method performed by the receiver.

In step S1810, the receiver generates pulses of a predetermined period during intervals of a predetermined period. Here, the predetermined period is less than half the OOK modulation period of the radio signal input to the antenna.

In step S1820, the receiver generates an oscillating signal based on the radio signal received by the antenna during the pulse. For example, if the radio signal input to the antenna is a '1' while the pulse is being generated, the receiver will start oscillating more quickly and oscillate for a longer period of time than if the radio signal were a '0'. .

In step S1830, the receiver measures the degree of oscillation of the oscillation signal during the pulse. For example, when a TDC is applied to the receiver, the receiver produces an output of the TDC that is proportional to the oscillation time that the oscillation signal oscillates as the degree of oscillation. Alternatively, if ED is applied to the receiver, the receiver detects the envelope of the oscillating signal as the degree of oscillation. Generating an oscillating signal in step S1820 and measuring the degree of oscillation in step S1830 are activated based on the pulse.

A radio signal is received based on the measured degree of oscillation. For example, a radio signal is received based on whether the output of the generated TDC exceeds a predetermined threshold. Alternatively, the wireless signal is received based on whether the amplitude of the detected envelope exceeds a predetermined threshold.

According to the reception method described above, a receiver with low power consumption, no response delay, and excellent reception sensitivity is provided. In addition, the power consumption of the receiver can be minimized because the receiver minimizes the active period according to the extremely short pulse and operates as a turn-off. In addition, average power consumption can be minimized by powering on the receiver at a period less than 1/2 times the OOK modulation period of the radio signal and operating in the minimum active period with no response delay. .

Since the items described above with reference to FIGS. 1 to 17 are applied as they are to each step shown in FIG. 18, a more detailed description will be omitted.

FIG. 19 is a flowchart illustrating a method of controlling the width of pulses generated by a pulse generator according to one embodiment.

FIG. 19 shows the process of controlling the pulse width performed by the receiver.

In step S1910, the receiver determines whether the measured degree of oscillation exceeds a predetermined threshold. For example, when a TDC is applied to the receiver, the TDC generates an output proportional to the oscillation time of the oscillating signal as the degree of oscillation, and the receiver determines whether the generated output of the TDC exceeds a predetermined threshold. to judge whether Alternatively, if an ED is applied to the receiver, the ED detects the envelope of the oscillating signal as the degree of oscillation, and the receiver determines whether the amplitude of the detected envelope exceeds a predetermined threshold. do.

If the measured degree of oscillation exceeds the predetermined threshold, in step S1920 the receiver reduces the pulse width output from the pulse generator. For example, the receiver reduces the pulse width by a predetermined amount or ratio.

Conversely, if the measured degree of oscillation does not exceed the predetermined threshold, the receiver increases the pulse width output from the pulse generator in step S1930. For example, the receiver increases the pulse width by a predetermined amount or ratio.

Once the pulse width is controlled in step S1920 or step S1930, step S1810 is performed.

Since the items described above with reference to FIGS. 1 to 18 are applied to each step shown in FIG. 19 as they are, a more detailed description will be omitted.

The above embodiments are realized by hardware components, software components, or a combination of hardware components and software components. For example, the devices and components described in this embodiment include processors, controllers, ALUs (arithmetic logic units), digital signal processors, microcomputers, FPAs (field programmable arrays), PLUs (programmable logic units), microprocessors, or different devices that execute and respond to instructions, may be implemented using one or more general-purpose or special-purpose computers. The processing device executes an operating system (OS) and one or more software applications that run on the operating system. The processing unit also accesses, stores, manipulates, processes, and generates data in response to executing the software. For convenience of understanding, the processing device may be described as being used as one, but those of ordinary skill in the art will understand that the processing device may include multiple processing elements and/or It can be seen that there are multiple types of processing elements. For example, a processing device may include multiple processors or a processor and a controller. Other processing configurations are also possible, such as parallel processors.

Software includes computer programs, code, instructions, or a combination of one or more of these, to configure and, independently or jointly, to direct the processor to operate as desired. Software and/or data are any type of machine, component, physical device, virtual device, computer storage medium or device, or signal transmitted to be interpreted by a processing device and to provide instructions or data to the processing device. Permanently or temporarily embodied through waves. The software may be distributed over network coupled computer systems so that it is stored and executed in a distributed fashion. Software and data are stored on one or more computer-readable media.

The method according to the present embodiment is embodied in the form of program instructions executed via various computer means and recorded in a computer-readable recording medium. The recording media may include program instructions, data files, data structures, etc. singly or in combination. The recording medium and program instructions may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well known and available to those having skill in the computer software arts. . Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, and magneto-optical media such as floptical disks. It includes media and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code, such as that generated by a compiler, as well as high-level language code that is executed by a computer, such as using an interpreter. A hardware device may be configured to act as one or more software modules to perform the operations described herein, and vice versa.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the technical scope of the present invention. It is possible to implement.

100, 200, 700, 1400, 1600 Receiver 110, 210, 730, 1310, 1430, 1610 Antenna 120, 230, 1630 Pulse Generator 130, 240, 1640 Oscillator 140 Measurement Section 220, 1620 Clock Generator 250 TDC (Time -to-Digital Converter)
710, 1410 controller 720, 1420 receiving main block 1510 to 1540 first to fourth cases 1650 ED (Envelope Detector)
1660 RF amplifier 1670 ADC (Analog-to-Digital Converter)

Claims (23)

a receiver,
an antenna for receiving radio signals;
a pulse generator for generating pulses;
an oscillator driven based on the pulse and generating an oscillating signal based on the radio signal;
a measuring unit that is driven based on the pulse and measures the degree of oscillation of the oscillation signal;
providing a first current to the oscillator during a first interval from the start of the pulse to an intermediate time of the pulse that lies between the start of the pulse and the end of the pulse; a current supplier that provides a second current, less than the first current, to the oscillator during a second interval from time to the end of the pulse ;
A receiver, wherein the radio signal is received based on the degree of oscillation of the oscillation signal. The measurement unit measures an oscillation time of the oscillation signal as an oscillation degree of the oscillation signal,
2. The receiver according to claim 1, wherein the radio signal is received based on the oscillation time of the oscillation signal measured by the measuring unit. The measurement unit generates an output proportional to the oscillation time of the oscillation signal,
3. The receiver of claim 2, wherein the radio signal is received based on whether the generated power exceeds a predetermined threshold. The radio signal is
received as a first value when the oscillation time of the oscillation signal is longer than a predetermined critical time;
3. The receiver of claim 2, wherein a second value different from the first value is received when the oscillation time of the oscillation signal is shorter than a predetermined critical time. 3. The receiver of claim 2, wherein the amplitude or frequency of the radio signal received by the antenna is received based on the oscillation time of the oscillating signal. further comprising two capacitors applied to said oscillator;
The two capacitors are mismatched with each other during a first interval from the beginning of the pulse to the midpoint of the pulse and matched with each other during a second interval from the midpoint of the pulse to the end of the pulse. is,
2. The receiver of claim 1, wherein the midpoint of the pulse lies between the start of the pulse and the end of the pulse. further comprising an inductor applied to the oscillator;
2. The receiver of claim 1, wherein the inductor has a Q-value greater than a threshold. The measurement unit generates an output proportional to the oscillation time of the oscillation signal,
3. The receiver according to claim 2, wherein the pulse generator adjusts the pulse width of the pulse based on the output generated by the measuring section. 3. The receiver according to claim 2, wherein the measuring unit generates an output proportional to the oscillation frequency of the oscillation signal and the pulse width of the pulse based on the oscillation time of the oscillation signal. 2. The receiver according to claim 1, wherein said pulse generator generates said pulse with a period smaller than half an OOK (On-Off Keying) modulation period of said radio signal. The measurement unit detects an envelope of the oscillation signal as the degree of oscillation of the oscillation signal,
2. The receiver of claim 1, wherein the radio signal is received based on the detected envelope. The measurement unit measures the amplitude of the detected envelope,
12. The receiver of claim 11 , wherein the radio signal is received based on whether the amplitude of the detected envelope exceeds a threshold. 2. The receiver of claim 1, wherein the oscillator and the measuring unit operate during a period during which the oscillator and the measuring unit receive the pulse from the pulse generator. 2. The receiver of claim 1, wherein the power consumption of the receiver is determined by the data rate of the radio signal and the pulse width of the pulse. 2. The receiver according to claim 1, further comprising an RF amplifier that is driven based on the pulse, amplifies the oscillation signal, and outputs the amplified oscillation signal to the measurement unit. A receiving method for a receiver comprising at least a pulse generator, an oscillator, a measuring unit, and a current supplier ,
generating pulses at a predetermined period with the pulse generator;
generating, with the oscillator , an oscillating signal based on a radio signal received by an antenna during the pulse;
measuring the degree of oscillation of the oscillation signal during the pulse by the measuring unit ;
The current supplier provides a first current to the oscillator during a first interval from the start of the pulse to an intermediate time of the pulse that lies between the start of the pulse and the end of the pulse. and
providing, by a current supplier, a second current, less than the first current, to the oscillator during a second interval from the middle of the pulse to the end of the pulse ;
generating the oscillating signal and measuring the degree of oscillation are activated based on the pulse;
A reception method, wherein the radio signal is received based on the degree of oscillation of the oscillation signal. The step of measuring the degree of oscillation generates an output proportional to the oscillation time of the oscillation signal as the degree of oscillation of the oscillation signal,
17. The method of claim 16 , wherein said radio signal is received based on whether said generated power exceeds a predetermined threshold. The step of measuring the degree of oscillation detects an envelope of the oscillation signal as the degree of oscillation of the oscillation signal;
17. The receiving method of claim 16 , wherein the radio signal is received based on whether the amplitude of the detected envelope exceeds a threshold. A computer-readable recording medium recording a program for executing the receiving method according to any one of claims 16 to 18 . a receiver,
an antenna for receiving radio signals;
a pulse generator that generates pulses during a predetermined period interval;
an oscillator driven based on said pulse to generate an oscillating signal based on said radio signal only during the presence of said pulse;
a measuring unit that is driven based on the pulse and measures the degree of oscillation of the oscillating signal that depends on the radio signal only while the pulse is present;
at least one of increasing the current supplied to the oscillator during the first interval of the pulse or adjusting the value of a capacitor applied to the oscillator during the first interval of the pulse; a fast start-up circuit that reduces the start-up time of the oscillator during the first interval of the pulse by
A receiver, wherein the radio signal is received based on the degree of oscillation of the oscillation signal. The measurement unit measures an oscillation time of the oscillation signal as the degree of oscillation of the oscillation signal, or detects an envelope of the oscillation signal as the degree of oscillation of the oscillation signal,
21. The receiver of claim 20 , wherein the radio signal is received based on an oscillation time of the oscillating signal or an envelope of the oscillating signal. The receiver is
a first oscillator producing a first clock signal having a first frequency and requiring a first power level to operate;
a second oscillator producing a second clock signal having a second frequency lower than the first frequency and requiring a second power level lower than the first power level to operate;
a selector that selects one of the first clock signal and the second clock signal based on the radio signal;
The pulse generator generates the pulse in the predetermined period based on one of the selected first clock signal and the second clock signal. 21. Receiver according to claim 20 . The selector selects the first clock signal if only the first frequency is at least twice the frequency of the radio signal, and both the first frequency and the second frequency are the frequency of the radio signal. 23. The receiver of claim 22 , wherein the receiver selects the second clock signal if it is at least twice .

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