JP2014168108A - Wireless transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption of the whole device by minimizing power consumption of an oscillator which generates carrier, in a wireless transmitter performing wireless transmission by generating a pulse modulation signal corresponding to an input signal, and superposing a carrier on that modulation signal.SOLUTION: A modulator 10 of dual pulse position modulation system generating two pulse signals having an interval, dependent on the signal level of an input signal Sin, for each constant time frame is used, and an on/off control oscillator 30 generating a carrier, being operated with a pulse signal outputted from the modulator 10 and stopping operation when the pulse signal is not inputted, is used. As a result, power consumption of a wireless transmitter can be reduced by oscillation stop of the oscillator 30, and since the oscillator 30 oscillates only twice for each constant time frame, power consumption of a wireless transmitter can be made constant.

Description

  The present invention relates to a radio transmission apparatus that generates a pulse modulation signal corresponding to an input signal and wirelessly transmits the pulse modulation signal by superimposing a transmission carrier wave on the pulse modulation signal.

  Conventionally, as shown in FIG. 23, this type of radio transmission apparatus generates a pulse modulation signal S1 corresponding to the signal level of an input signal, and the generated pulse modulation signal S1 and an oscillation signal S2 output from the oscillator 2 Are mixed using a mixer 4 to generate a transmission signal Sout in which a carrier wave composed of an oscillation signal S2 is superimposed on the pulse modulation signal S1.

  Further, as shown in FIG. 24, in this type of wireless transmission apparatus, the following modulation methods a) to e) are known as pulse modulation methods used to generate the pulse modulation signal S1 from the input signal Sin. (See, for example, Patent Document 1, Non-Patent Document 1, etc.).

a) Pulse Amplitude Modulation (PAM) that changes the amplitude of the pulse at a fixed period (time frame).
b) A pulse width modulation method (PWM: Pulse width modulation) in which the on-time (that is, duty ratio) of the pulse is changed every fixed period (time frame).

c) Pulse position modulation method (PPM: Pulse Position modulation) in which the position of the pulse is changed at regular intervals (time frames).
d) Pulse interval modulation method (PIM: Pulse Interval modulation) which changes the generation interval of short pulses.

e) Pulse frequency modulation method (PFM: Pulse Frequency modulation) that changes the frequency of short pulses.
By the way, this type of wireless transmission device is miniaturized as an integrated circuit for wireless communication (see, for example, Patent Document 2) and may be incorporated into a smart sensor together with a sensor element and a CPU for signal processing.

  Smart sensors have functions for storing, processing, and transferring detection information by sensor elements, and communicate with each other between smart sensors and other control devices based on their own decision making. A battery or a power generation device is used (see, for example, Patent Document 3).

  For this reason, when the wireless transmission device is incorporated in a smart sensor, it is necessary to reduce the power consumption of the wireless transmission device itself in order to suppress the power consumption of the entire smart sensor.

JP 2001-208511 A JP 2007-281305 A Special table 2008-502404 gazette

B. Wilson, Z. Ghassemlooy, “Pulse time modulation techniques for optical communication: A review”, IEE Proceedings-J, 140, pp.346-348, 1993.

  However, in the above-described conventional wireless transmission apparatus, the oscillator is always operated regardless of the state of the pulse modulation signal. Therefore, the oscillator operates unnecessarily when the pulse modulation signal is low and does not transmit a carrier wave. As a result, there is a problem that the power consumption of the wireless transmission device cannot be reduced.

  On the other hand, in order to prevent this problem, the oscillator is operated only when the pulse modulation signal is at a high level and it is necessary to transmit a carrier wave, and when the pulse modulation signal is at a low level, the operation of the oscillator is stopped. Can be considered.

However, in the conventional pulse modulation method, the power consumption cannot be sufficiently reduced only by such measures.
That is, first, in the pulse amplitude modulation method (PAM), the pulse width of the pulse modulation signal is constant. If the pulse width is shortened to shorten the operation time of the oscillator 2 (carrier wave transmission time), the receiving apparatus side Since it becomes impossible to accurately detect the signal level of the input signal from the amplitude of the pulse modulation signal, there is a limit in reducing the power consumption by shortening the operation time of the oscillator.

  Further, in the pulse width modulation method (PWM), when the signal level of the input signal is high and the duty ratio of the pulse width modulation signal is close to 100%, the power consumption by the oscillator cannot be limited.

  Further, in the pulse interval modulation method (PIM), when the signal level of the input signal is low, the frequency of occurrence of short pulses increases, so that the power consumption by the oscillator cannot be sufficiently reduced. Conversely, the pulse frequency modulation method In (PFM), when the signal level of the input signal is high, the frequency of occurrence of short pulses increases, so that the power consumption by the oscillator cannot be sufficiently reduced.

  On the other hand, in the pulse position modulation method (PPM), only the position of a short pulse is changed according to the signal level of the input signal, so that the operating time of the oscillator corresponding to the pulse is shortened to reduce power consumption. I can.

  However, in the pulse position modulation method (PPM), it is necessary to synchronize the time frame between the transmitting device and the receiving device, and a synchronization signal is periodically generated in the wireless transmitting device for the synchronization. Therefore, it is necessary to provide a circuit for transmission, and the power consumption of the entire wireless transmission device cannot be reduced by the power consumption of the circuit.

  The present invention has been made in view of such problems, and generates a carrier wave in a wireless transmission device that generates a pulse modulation signal corresponding to an input signal and wirelessly transmits the pulse modulation signal by superimposing a transmission carrier wave on the pulse modulation signal. It is an object of the present invention to reduce the power consumption of the oscillator to reduce the power consumption of the entire apparatus by reducing the power consumption of the oscillator more efficiently.

  The radio transmission apparatus according to claim 1, wherein the pulse modulation means generates two pulse signals having an interval corresponding to the signal level of the input signal for each fixed time frame. Then, the oscillation means receives the generated pulse signal and oscillates to generate a carrier wave for wireless communication.

  Therefore, according to the wireless transmission device of the present invention, the time during which the oscillating means is in the oscillation state is reduced by reducing the pulse width of the pulse signal generated twice per fixed time frame by the pulse modulating means. It can be limited to the same level as when a pulse modulation signal by the pulse position modulation method (PPM) is used.

  For this reason, according to the wireless transmission device of the present invention, a modulation method other than the above-described pulse position modulation method (PPM) (that is, a modulation method such as PAM, PWM, PIM, PFM, etc.) is used as the modulation method of the pulse modulation means. Power consumption can be reduced compared with the case where it employ | adopts.

  Further, in the present invention, as a modulation method of the pulse modulation means, a modulation method (hereinafter referred to as a dual pulse position modulation method) that generates two pulse signals whose intervals change according to the signal level of the input signal for every fixed time frame. : Called DPPM), the receiving device can recover the input signal by detecting the pulse interval between the two pulse signals.

  According to the present invention, the synchronization signal is transmitted from the transmission side so that the input signal can be restored on the reception device side, as when the pulse position modulation method (PPM) is adopted as the pulse modulation method. There is no need.

  Therefore, according to the wireless transmission device of the present invention, the configuration of the wireless transmission device can be simplified and wireless compared with the case where the pulse position modulation method (PPM) is adopted as the modulation method of the pulse modulation means. The power consumption of the transmission device can be reduced.

  In the present invention, since two pulse signals are generated every certain time frame, in order to restore the input signal on the receiving device side, any of the pulse signals sequentially obtained from the received signal is the head of the time frame. It is necessary to be able to identify whether it is a pulse.

  For this purpose, the first pulse signal generated from the received signal (carrier wave) on the receiving device side is the first pulse in the time frame, the next received pulse signal is the second pulse in the same time frame, The next received pulse signal is identified as the first pulse in the next time frame, and so on, and the type of the pulse signal (first and second) is identified in the order of reception of the pulse signal, and the interval between the two pulse signals. The input signal may be restored from the above.

  However, more preferably, the pulse width of the first pulse signal and the pulse width of the second pulse signal are constant and different from each other among the two pulse signals generated by the pulse modulation means per fixed time frame. The pulse modulation means may be configured to have a width.

  That is, in this way, every time a pulse signal is generated from a received signal (carrier wave) on the receiving device side, it is determined from the pulse width of the pulse signal whether the currently received pulse signal is the first pulse in the time frame. It becomes possible to more accurately identify whether the pulse is the first pulse, and the input signal can be accurately restored from the interval between the two pulse signals.

  Next, according to the pulse modulation means of the present invention, the reference signal generation means for generating a reference signal whose signal level changes in a sawtooth shape every certain time frame, and the reference signal generation means Comparison means for generating a pulse width modulation signal having a pulse width corresponding to the signal level of the input signal by comparing the generated reference signal and the input signal, and rise of the pulse width modulation signal generated by the comparison means A pulse signal generating means for generating a pulse signal at each of the timing and the rising timing may be used.

  In other words, in this way, the pulse signal generating means for generating the pulse signal at the rising timing and the rising timing of the pulse width modulation signal is added to the general pulse width modulation circuit composed of the reference signal generating means and the comparing means. By providing, a pulse modulation means can be comprised.

Further, the pulse signal generating means can be easily realized by using a differentiation circuit whose signal level changes at the edge of the pulse signal.
Therefore, according to the wireless transmission device of the second aspect, the pulse modulation means can be realized with an extremely simple circuit configuration.

Next, in the wireless transmission apparatus of the present invention, if the pulse modulation means and the oscillation means are formed on a silicon substrate as an integrated circuit for wireless transmission, the entire apparatus can be reduced in size.
When the pulse modulating means and the oscillating means are formed on the silicon substrate as described above, the oscillating means generates the spiral pattern on the surface of the silicon substrate as described in claim 3. It is preferable to provide an antenna (so-called on-chip antenna) for radiating the generated carrier wave.

  In other words, in this way, a wireless transmission device capable of obtaining stable transmission characteristics can be produced by setting in advance the number of turns of the spiral pattern formed on the silicon substrate surface and the size of the outer periphery (for example, the diameter). be able to.

The technology for forming a spiral pattern on a silicon substrate is described in the following technical literature.
Technical literature: Jong-Wan Kim, Hidekuni Takao, Kazuaki Sawada, Makoto Ishida, “Integrated Inductors for RF Transmitters in CMOS / MEMS Smart Microsensor System”, Sensors, Volume 7, PP.1387-1398, 2007.

  However, the technique disclosed in this technical document forms an on-chip antenna composed of a spiral pattern and a capacitor on a silicon substrate, and impedance matching is performed between the on-chip antenna and a communication circuit formed on the silicon substrate. The connection is made by wire bonding using an inductor.

  Therefore, when the spiral pattern is formed using this technique, an inductor for impedance matching is provided, and there is a problem that the antenna becomes large due to this inductor.

  Therefore, when the wireless transmission device including the antenna is formed on the silicon substrate as described in claim 3, the spiral pattern is further connected to the wiring pattern on the silicon substrate as described in claim 4. It is preferable to directly connect to the integrated circuit for wireless transmission, and to adjust the impedance of the spiral pattern viewed from the connection portion with the integrated circuit for wireless transmission by adjusting the width and interval of the spiral pattern. .

  In other words, in this way, it is not necessary to connect the spiral pattern and the wireless transmission integrated circuit by wire bonding using an inductor for impedance matching, so the wireless transmission device including the antenna is configured as an integrated circuit. The manufacturing process can be simplified, and the wireless transmission device can be reduced in size because there is no inductor for impedance matching.

  Next, according to the radio transmission apparatus of the present invention (claims 1 to 4), the conventional pulse modulation method is adopted by adopting the dual pulse position modulation method (DPPM) unique to the present invention as the modulation method of the input signal. Power consumption can be reduced compared to those employing (PAM, PWM, PIM, PFM, PPM, etc.).

  For this reason, the wireless communication device of the present invention (Claims 1 to 4) is a smart sensor including a sensor element and a signal processing unit that processes a detection signal from the sensor element, as described in Claim 5, If the output from the signal processing means is used as a wireless transmission device that wirelessly transmits, the effect can be effectively exhibited.

  That is, as described above, since the smart sensor is required to reduce power consumption, the wireless transmission device of the present invention is used as a wireless transmission device that wirelessly transmits an information signal such as a detection signal in the smart sensor. By doing so, the power consumption of the smart sensor can be reduced.

  In particular, according to the wireless transmission device according to claims 3 and 4, since it can be reduced in size by being formed on the silicon substrate together with the antenna, if this wireless transmission device is provided in the smart sensor. Also, the smart sensor can be miniaturized.

It is a block diagram showing the structure of the whole radio | wireless transmitter of 1st Embodiment. It is a block diagram showing the structure of the dual pulse position modulation apparatus of 1st Embodiment. It is a time chart explaining operation | movement of the dual pulse position modulation apparatus of 1st Embodiment. It is a block diagram showing the structure of the on / off control oscillation apparatus of 1st Embodiment. It is explanatory drawing showing schematic structure of the radio | wireless transmission apparatus of 2nd Embodiment which formed each circuit of the radio | wireless transmission apparatus on the silicon substrate with the antenna. It is AA sectional drawing showing the cross section of the antenna on the silicon substrate shown in FIG. It is explanatory drawing showing the equivalent circuit of the antenna of 2nd Embodiment. FIG. 6 is a cross-sectional view illustrating a state after contact holes are formed in a CMOS manufacturing process of the wireless transmission device illustrated in FIG. 5. It is sectional drawing showing the state which accumulated Al after the manufacturing process shown in FIG. FIG. 10 is a cross-sectional view illustrating a state in which wiring and antenna patterns are formed after the manufacturing process illustrated in FIG. 9. It is sectional drawing showing the state after forming a wireless transmission integrated circuit and an antenna on a silicon substrate using a CMOS manufacturing process. It is a time chart showing the measurement result of the operation waveform of the dual pulse position modulation device of a 2nd embodiment. It is explanatory drawing showing the 1st pulse signal produced | generated in the dual pulse position modulation apparatus of 2nd Embodiment. It is explanatory drawing showing the 2nd pulse signal produced | generated in the dual pulse position modulation apparatus of 2nd Embodiment. It is explanatory drawing showing operation | movement of the oscillation apparatus of 2nd Embodiment. It is explanatory drawing showing the measurement result of the return loss of the antenna of 2nd Embodiment. It is explanatory drawing showing the measurement result of the voltage standing wave ratio (VSWR) of the antenna of 2nd Embodiment. It is explanatory drawing showing the measurement result of the input impedance of the antenna of 2nd Embodiment. It is explanatory drawing showing the measurement result of the radiation pattern of the xy-axis direction of the antenna of 2nd Embodiment. It is explanatory drawing showing the measurement result of the radiation pattern of the yz-axis direction of the antenna of 2nd Embodiment. It is explanatory drawing showing the structure of the measurement system used in measuring the transmission radio wave from the radio | wireless transmitter of 2nd Embodiment. It is explanatory drawing showing the measurement result by the measurement system shown in FIG. It is a block diagram showing schematic structure of the conventional radio | wireless transmitter. It is explanatory drawing showing the kind and pulse modulation signal of the conventional pulse modulation system.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
The wireless transmission device of the present embodiment is used by being incorporated in a smart sensor together with a sensor element and a CPU for signal processing, and is configured as shown in FIG.

  That is, the wireless transmission device according to the present embodiment includes a dual pulse position modulation device 10 that performs pulse modulation on an information signal (in other words, an input signal) Sin output from a sensor element or CPU that constitutes a smart sensor, and dual pulse position modulation. An on / off control oscillator that starts an oscillation operation in response to the pulse modulation signal S1 output from the device 10 and stops the oscillation operation when the output of the pulse modulation signal S1 from the dual pulse position modulation device 10 is stopped. 30 and a power amplifying device 40 that generates a transmission signal Sout by amplifying power of an oscillation signal (that is, a wireless transmission carrier wave) S2 generated by the oscillation operation of the on / off control oscillation device 30.

The transmission signal Sout generated by the power amplification device 40 is output to the antenna 50 and is radiated from the antenna 50 as a transmission radio wave.
Next, the dual pulse position modulation device 10 corresponds to the pulse modulation means of the present invention, and generates a reference signal Sst whose signal level changes in a sawtooth shape every certain time frame as shown in FIG. By comparing the sawtooth wave generator 12 and the sawtooth reference signal Sst output from the sawtooth generator 12 with the input signal Sin, a pulse width corresponding to the signal level of the input signal Sin is obtained. And a comparator 14 that generates a pulse width modulation signal S11.

  Then, the pulse width modulation signal S11 generated by the comparator 14 is distributed into two systems, one of the distributed pulse width modulation signals S11 is directly input to the differentiator 18, and the other pulse width modulation signal S11 is The signal is input to the differentiator 20 via an inverter (NOT gate) 16.

  As a result, the differential device 18 outputs a differential signal S12 that rises in synchronization with the rise of the pulse width modulation signal S11, and the differentiator 20 outputs a differential signal S13 that rises in synchronization with the fall of the pulse width modulation signal S11. Is output (see FIG. 3).

The outputs from the differentiators 18 and 20 are input to the NAND gate 26 via the inverters 22 and 24, respectively.
The inverters 22 and 24 are low when the output level from the differentiators 18 and 20 is greater than or equal to the threshold value, and when the output level from the differentiators 18 and 20 is less than the threshold value. It is configured to output a high level signal.

  As a result, the NAND gate 26 outputs the pulse signals P1 and P2 that are at a high level for a certain time determined by the time constants of the differentiating devices 18 and 20, in synchronization with the rising timing and falling timing of the pulse width modulation signal S11. The interval between the two pulse signals P1 and P2 changes according to the pulse width of the pulse width modulation signal S11 (in other words, the signal level of the input signal Sin) (FIG. 3). reference).

  That is, the dual pulse position modulation device 10 sets one cycle of the reference signal (sawtooth wave) generated by the sawtooth wave generation device 12 as a time frame T, and is spaced according to the signal level of the input signal Sin for each time frame T. Thus, two pulse signals P1 and P2 that change are generated.

  In the present embodiment, by setting the time constant of the differentiating device 20 to a value larger than the time constant of the differentiating device 18, two of the two pulse signals P1 and P2 generated for each time frame T are represented by 2 The pulse width of the second pulse signal P2 generated is set to be larger than the pulse width of the pulse signal P1 generated first (see FIG. 3).

  This is because when the pulse signal is generated from the received signal on the receiving device side, whether the pulse signal received this time is the first pulse width or the second pulse signal of the time frame based on the pulse width of the pulse signal. This is so that it can be identified.

  Here, in this embodiment, the sawtooth wave generator 12 corresponds to the reference signal generator of the present invention, the comparator 14 corresponds to the comparator of the present invention, the inverter 16, the differentiators 18, 20 and the inverter. 22 and 24 and the NAND gate 26 correspond to the pulse signal generating means of the present invention.

  Next, the on / off control oscillator 30 corresponds to the oscillation means of the present invention. As shown in FIG. 4, a two-input NAND gate 32 and two inverters 34 and 36 are sequentially connected in series. The output of the inverter 36 at the final stage is configured by a known ring oscillation circuit in which one output terminal of the NAND gate 32 is connected.

  In the ON / OFF control oscillation device 30 configured as described above, if the other input terminal of the NAND gate 32 is low level, the output of the NAND gate 32 is low level, the output of the inverter 34 is high level, When the output is at a low level, the oscillation is stopped, and when the other input terminal of the NAND gate 32 is at a high level, the output of the NAND gate 32, the inverter 34, and the inverter 36 is sequentially inverted.

  Therefore, in the present embodiment, the pulse modulation signal S1 from the dual pulse position modulation device 10 is input to the other input terminal of the NAND gate 32 as a control signal for switching oscillation / stop of the on / off control oscillation device 30.

  As a result, the on / off control oscillation device 30 enters the oscillation state only when the pulse modulation signal S1 (specifically, the pulse signal P1 or P2) is output from the dual pulse position modulation device 10, and the inverter 36 The output is output as an oscillation signal (in other words, a carrier wave) S2 to the power amplifier 40, and when the pulse signal P1 or P2 is not output from the dual pulse position modulator 10, the on / off control oscillator 30 performs an oscillation operation. Will stop.

  As described above, in the wireless transmission device according to the present embodiment, the dual pulse position modulation method (DPPM) is adopted to generate the pulse modulation signal corresponding to the input signal Sin, and the dual pulse position modulation method ( DPPM) is used to oscillate the on / off control oscillation device 30 using two pulse signals generated every fixed time frame.

  Therefore, according to the wireless transmission device of the present embodiment, a pulse modulation signal is generated by a conventional pulse modulation method (PAM, PWM, PIM, PFM, PPM, etc.), and the generated pulse modulation signal is turned on / off. Compared with the case where the oscillation operation of the off-control oscillation device 30 is switched, the operation time of the on-off control oscillation device 30 can be shortened and the amount of power consumed by the wireless transmission device can be reduced.

Further, unlike the case of adopting the conventional pulse position modulation method (PPM), it is not necessary to generate a synchronization signal for synchronizing the time frame between the transmission device side and the reception device side. The apparatus configuration can be simplified.
[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  As shown in FIG. 5, the wireless communication device according to the present embodiment includes a wireless transmission integrated circuit 60 including the above-described dual pulse position modulation device 10, on / off control oscillation device 30, and power amplification device 40. The wireless communication device according to the first embodiment including the antenna 50 is integrally formed on the silicon substrate by forming the spiral pattern 70 on the surface of the silicon substrate using a CMOS manufacturing process. It is.

  The spiral pattern 70 constituting the antenna 50 adjusts the number of turns and the outer diameter Dout to determine the inductance of the spiral pattern 70 and the capacitance between the spiral pattern 70 and the silicon substrate. The corresponding resonance frequency is set, and the width of the spiral pattern 70 and the interval between the spiral patterns 70 are adjusted so that the transmission signal is not reflected at the connection portion between the spiral pattern 70 and the wireless transmission integrated circuit 60. Alignment is made.

Hereinafter, this point will be described in detail.
First, the spiral pattern 70 is formed on the silicon substrate by growing an insulating film (SiO ₂ ) on the silicon substrate and forming a metal layer (Al) thereon, and the cross section thereof is shown in FIG. As shown.

An equivalent circuit based on the design parameters of the spiral pattern 70 can be described as shown in FIG.
That is, in the equivalent circuit shown in FIG. 7, Ls is an inductance component of the spiral pattern 70, and is expressed by the following equation (1).

In equation (1), n is the number of turns, μ is the magnetic permeability, and 4π × 10 ⁻⁷ H / m, and c1, c2, c3, and c4 are coefficients depending on the shape of the spiral pattern.
In the equivalent circuit shown in FIG. 7, Rs is a resistance component caused by the metal forming the spiral pattern 70, Cox is a parasitic capacitance component generated between the silicon substrate and the metal layer, and Csi is a capacitance component of the silicon substrate. , Rsi are resistance loss components generated from the substrate.

  Further, the values of the parasitic components of the spiral pattern 70 are expressed by the following equations (2) to (5).

  Here, w is the width of the spiral pattern 70, t is the thickness of the spiral pattern 70, l is the length of the spiral pattern 70, δ is the skin depth from the frequency used, and ρ is the resistance of the metal .Epsilon.ox is the dielectric constant of the oxide film, tox is the thickness of the insulating film, Csub is the capacitance of the silicon substrate, and Gsub is the conductivity per unit area.

  The resonance frequency of the spiral pattern 70 is expressed by the following equation (6) according to the inductance and capacitance components obtained from the equivalent circuit by the equations (1) to (5).

  As apparent from the equation (1), since the inductance of the spiral pattern 70 varies greatly depending on the number of turns or the outer diameter Dout, the operating frequency of the antenna 50 can be adjusted by adjusting these parameters.

  As is clear from the equations (2) to (5), when the number of turns of the spiral pattern 70 and the outer diameter Dout are fixed and the width of the spiral pattern 70 or the interval between the patterns changes, the inductance component The change of the parasitic component becomes larger than the change. However, since the value of the parasitic capacitance is small, the change in the resonance frequency is small, but the parasitic capacitance / resistance component has an effect of changing the impedance of the spiral pattern 70 (in other words, the antenna 50).

  Therefore, by adjusting the number of turns of the spiral pattern 70 and the outer diameter Dout, the resonance frequency of the spiral pattern 70 (in other words, the operating frequency of the antenna 50) can be set, and the width or interval of the spiral pattern 70 is adjusted. Thus, the impedance can be matched with the wireless transmission integrated circuit 60.

  For example, when the 300 MHz band antenna 50 used for the smart sensor for human monitoring is configured by the spiral pattern 70 formed on the silicon substrate, the number of turns of the spiral pattern 70 is 11 and the outer diameter Dout is 1. If the design is 2 mm, the width of the spiral pattern 70 is 20 μm, and the distance between the spiral patterns 70 is 20 μm, the inductance is 93.5 nH, Cox is 12.4 pF, Csi is 3.2 pF, Rs is 50.4Ω, and Rsi is 185 kΩ. Thus, the operating frequency of the antenna 50 can be calculated as 325 MHz, and the input impedance as 50.4Ω.

In this case, the coefficient when the insulating film (SiO ₂ ) between the circuit wiring and the silicon substrate is 1.5 μm, and the spiral pattern 70 is circular as shown in the figure, c1 is 1, c2 is 2.46, c3 Is 0 and c4 is 0.2.

  As described above, in the wireless communication device of this embodiment, the wireless transmission integrated circuit 60 including the dual pulse position modulation device 10, the on / off control oscillation device 30, and the power amplification device 40 is formed on a silicon substrate. By forming the spiral pattern 70 on the surface of the silicon substrate, the wireless communication device including the antenna 50 is integrally formed on the silicon substrate, so that an extremely small wireless communication device with low power consumption can be realized.

  In particular, in the present embodiment, the operating frequency frequency and impedance of the antenna 50 can be set by adjusting the number of turns of the spiral pattern 70, the outer diameter Dout, the width of the spiral pattern 70, and the interval therebetween. By determining each of these parameters, the antenna 50 capable of obtaining desired antenna characteristics can be formed on the silicon substrate.

  Further, as described above, the impedance of the antenna 50 can be set as appropriate by adjusting the width of the spiral pattern 70 and the interval thereof. Therefore, when the antenna 50 is connected to the wireless transmission integrated circuit 60, the impedance matching inductor is used. Can be directly connected by a connection pattern formed on a silicon substrate.

Therefore, according to the wireless transmission device of the present embodiment, the manufacturing cost can be reduced by reducing the man-hour when the wireless communication device including the antenna 50 is integrally formed on the silicon substrate.
[Experimental example]
Next, the above-described wireless communication apparatus according to the second embodiment was designed, manufactured, and evaluated in an LSI design environment using CAD (Computer Aided Design) manufactured by Cadence.

This evaluation result will be described as an experimental example of the second embodiment.
Here, in manufacturing the wireless communication device, the wireless transmission integrated circuit 60 is formed on the silicon substrate 80 (specifically, n-type Si (100)) in the well-known CMOS manufacturing process. Then, an insulating film 81 made of SiO ₂ was formed.

  Then, as shown in FIG. 8, after forming contact holes 90 for wiring in the formation region of the wireless transmission integrated circuit 60, the process of forming the wiring of the wireless transmission integrated circuit 60 and the spiral pattern 70 is entered. By the procedure, the wiring of the wireless transmission integrated circuit 60 and the spiral pattern 70 were formed.

  That is, as shown in FIG. 9, first, an aluminum layer (Al layer) 92 is deposited using an Al sputtering apparatus in order to form the wiring of the wireless transmission integrated circuit 60 and the spiral pattern 70.

  Next, as shown in FIG. 10, a resist 94 for forming the wiring and spiral pattern 70 of the wireless transmission integrated circuit 60 is formed on the Al layer 92, and Al using a RIE (Reactive Ion Etching) apparatus. Layer 92 is etched.

Then, after etching the Al layer 92, the resist 94 remaining on the substrate surface is removed.
As a result, as shown in FIG. 11, the wiring 95 and the spiral pattern 70 of the wireless transmission integrated circuit 60 are formed by using the wiring forming process of the CMOS manufacturing process.

  8 to 11, reference numeral 82 denotes a p-well region, reference numeral 83 denotes an n-MOS channel stopper, reference numeral 84 denotes a p-MOS channel stopper, reference numeral 85 denotes an n-MOS source / drain region, reference numeral Reference numeral 86 denotes a p-MOS source / drain region, reference numeral 87 denotes a channel stopper (n +), reference numeral 88 denotes a channel stopper (p +), and reference numeral 89 denotes a poly-Si film.

Next, the radio transmission integrated circuit 60 formed on the silicon substrate 80 in the above procedure is driven with a power supply voltage of 5 V, and the operation waveforms of the respective parts of the radio transmission integrated circuit 60 and the radiation of the antenna 50 including the spiral pattern 70 are emitted. Characteristics were measured.
(Operating characteristics of the wireless transmission integrated circuit 60)
FIG. 12 shows an input signal (information signal) Sin to the dual pulse position modulator 10, a reference signal Sst output from the sawtooth generator 12, an output (pulse width modulation signal) S11 from the comparator 14, and a dual The measurement result of the output (pulse modulation signal consisting of two pulse signals generated by DPPM) S1 from the pulse position modulation device 10 is shown.

  From this measurement result, in the dual pulse position modulation device 10, the pulse signal P1 generated when the input signal Sin becomes higher than the sawtooth wave (reference signal) Sst (in other words, the rising timing of the pulse width modulation signal S11). Of the pulse signal P2 generated when the input signal Sin becomes lower than the sawtooth wave (reference signal) Sst (in other words, the falling timing of the pulse width modulation signal S11). The pulse width was 2 μs (see FIG. 14), and it was confirmed that the pulse widths of these two pulse signals P1 and P2 were different.

  FIG. 15 shows an oscillation signal output from the on / off control oscillation device 30 when the on / off control oscillation device 30 starts an oscillation operation by the pulse modulation signal S1 output from the dual pulse position modulation device 10. The measurement result of measuring (carrier wave) S2 is shown.

  Then, when the power consumption in the wireless transmission integrated circuit 60 that changes as the operating state of the on / off control oscillation device 30 is switched as described above is measured, the on / off control oscillation device 30 is in the oscillation stop state. The power consumption consumed by the on / off control oscillation device 30 and the power amplification device 40 is 2.45 mW. When the on / off control oscillation device 30 is in the oscillation state, the on / off control oscillation device 30 and power The power consumption consumed by the amplifying device 40 was 10.45 mW, and the power consumption of the dual pulse position modulation device 10 was 4 mW.

Moreover, the average power consumption consumed by the dual pulse position modulation device 10 and the on / off control oscillation device 30 was 7.0 mW.
On the other hand, the power consumption consumed by the dual pulse position modulation device 10 and the conventional oscillation device that cannot be controlled on / off was 14.5 mW or more.

  As a result, according to the wireless transmission device of this embodiment, it was confirmed that the power consumption can be reduced by 50% or more compared to the case where the dual pulse position modulation device 10 and the conventional oscillation device are combined.

  On the other hand, as a modulation device for generating a pulse modulation signal from an input signal, a pulse width modulation (PWM) device composed of a sawtooth wave generator 12 and a comparator 14 is used. When the wireless transmission integrated circuit is configured using the oscillation device 30, the power consumption changes within a range of 8.4 to 14.5 mW, and the power consumption may be larger than that of the wireless transmission device of the present embodiment. all right.

  Note that the power consumption changes in this way because the duty ratio of the pulse modulation signal changes depending on the input signal (information signal). From this measurement result, the same applies to the pulse interval modulation method and the pulse frequency modulation method. It can be expected that the power consumption will change.

On the other hand, in the wireless transmission device of the present embodiment, by adopting the dual pulse position modulation method, two short pulse signals are generated for every fixed time frame, and the on / off control oscillation device 30 is generated by the pulse signals. Since the power is driven, the power consumption can be made substantially constant.
(Characteristics of antenna 50)
Next, the antenna 50 of this embodiment configured with the spiral pattern 70 as described above had an operating frequency of 300 MHz and a return loss of −24 dB as shown in FIG. Further, as shown in FIG. 17, the bandwidth was 270 to 360 MHz under the condition of VSWR (Voltage Standing Wave Ratio) <2.

  Further, the input impedance is 51Ω as shown in FIG. 18, and the radiation pattern is as shown in FIGS. 19 and 20, and it was found that the input impedance is substantially omnidirectional. The maximum gain is −40 dBi.

  Here, the error between the calculated value of the antenna characteristic and the measured value of the embodiment is caused by the error of the expression for obtaining the inductance and parasitic component of the spiral pattern 70 and the error generated in the manufacturing process. is there.

  In this embodiment, since the antenna 50 is formed by the spiral pattern 70 and the operating frequency is adjusted and impedance matching is performed using the parasitic component, the length corresponding to the wavelength as described in Patent Document 2 is used. As compared with an antenna using a line pattern or an antenna using an on-chip antenna and an impedance matching inductor as described in the technical literature described above, the size can be reduced.

In addition, since the antenna 50 can be manufactured by using a wiring formation process during the manufacturing process of the wireless transmission integrated circuit 60, a manufacturing process dedicated to the antenna 50 can be eliminated.
Next, in order to confirm a transmission signal from the wireless transmission device manufactured as described above, a wireless transmission device is used by using the reception system shown in FIG. 21 that includes a standard dipole antenna, a low noise amplifier (LNA), and an oscilloscope. The transmission signal from was measured.

  FIG. 22 shows the measurement result. From this measurement result, according to the wireless transmission device of this embodiment, an antenna in which the pulse modulation signal generated by the dual pulse position modulation method is formed by the spiral pattern 70 is shown. 50 can be transmitted normally, and it has been found that the receiving side can identify two pulse signals generated every certain time frame from the received signal and detect the signal level of the input signal from the pulse interval. .

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken in the range which does not deviate from the summary of this invention.
For example, in the above-described embodiment, the spiral pattern 70 formed on the silicon substrate has been described as having a circular shape. However, the spiral pattern 70 may have a polygonal shape such as a square or a hexagon.

  In the above embodiment, the wireless transmission device is described as being incorporated and used in a smart sensor. However, the wireless transmission device of the present invention may be any device that wirelessly transmits a pulse modulation signal. But it can be used.

  In addition, according to the wireless transmission device of the present invention, it is possible to reduce power consumption compared to the conventional one, and as described in the second embodiment, an IC is formed as a semiconductor integrated circuit (in other words, Therefore, when applied to an apparatus that requires low power consumption or miniaturization, the effect can be effectively exhibited.

  DESCRIPTION OF SYMBOLS 2 ... Oscillator, 4 ... Mixer, 10 ... Dual pulse position modulation device, 12 ... Saw wave generator, 14 ... Comparator, 16, 22, 24 ... Inverter, 18, 20 ... Differentiation device, 26 ... NAND gate, 30 ... ON / OFF controlled oscillation device, 32 ... NAND gate, 34, 36 ... inverter, 40 ... power amplification device, 50 ... antenna, 60 ... wireless transmission integrated circuit, 70 ... spiral pattern, 80 ... silicon substrate, 81 ... insulating film, 90 ... contact hole, 92 ... Al layer, 94 ... resist, 95 ... wiring.

Claims (5)

Pulse modulation means for generating two pulse signals having an interval corresponding to the signal level of the input signal for each fixed time frame;
Oscillating means switchable to an oscillation state or an oscillation stop state for generating a carrier wave for wireless communication by a control signal;
And the pulse signal generated by the pulse modulation means is input to the oscillating means as the control signal, so that the oscillation operation of the oscillating means is limited when the pulse signal is generated. A wireless transmission device. The pulse modulation means includes
A reference signal generating means for generating a reference signal whose signal level changes in a sawtooth shape for each predetermined time frame;
Comparison means for generating a pulse width modulation signal having a pulse width corresponding to the signal level of the input signal by comparing the input signal and the reference signal generated by the reference signal generation means;
Pulse signal generating means for generating the pulse signal at the rising timing and the rising timing of the pulse width modulation signal generated by the comparing means;
The wireless transmission device according to claim 1, further comprising:   The pulse modulation means and the oscillation means are formed on a silicon substrate as an integrated circuit for wireless transmission, and an antenna for radiating a carrier wave generated by the oscillation means is formed on the surface of the silicon substrate. The wireless transmission device according to claim 1, wherein a spiral pattern is formed.   The spiral pattern is directly connected to an integrated circuit for wireless transmission via a wiring pattern on the silicon substrate, and the impedance of the spiral pattern viewed from the connection portion adjusts the width and interval of the spiral pattern. 4. The wireless transmission device according to claim 3, wherein impedance matching is performed with said integrated circuit for wireless transmission.   The wireless transmission device is provided as a wireless transmission device that wirelessly transmits an output from the signal processing unit to a smart sensor including a sensor element and a signal processing unit that performs signal processing on a detection signal from the sensor element. The wireless transmission device according to any one of claims 1 to 4.