JP2006217013A - Cofdm modulation signal receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure basic performances of a receiver such as tracking performance, selectivity characteristics of a filter, noise figure of an RF amplifier, power gain characteristics, receiving sensitivity, frequency selectivity characteristics, receiving information quality, and the like, through a single tuner, single IF stage arrangement. <P>SOLUTION: The band limit filters at the RF stage and IF stage of a COFDM modulation signal receiver employ variable band tuning double-tuned tracking filters 3, 7, 8, 12 and controllable impedance matching units 4, 6, 9, 11 are provided at the RF stage. Consequently, basic performances of the receiver such as receiving information quality can be ensured through a single tuner, single IF stage arrangement. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a COFDM modulated signal receiver, and more particularly to improving the performance of an RF stage and an IF stage that receive a COFDM modulated signal.

  As an example of a conventional COFDM modulated signal receiver, a DAB mobile receiver that has been internationally standardized earliest in COFDM will be described. FIG. 2 shows the reception of DAB (“ETS300401”), which is an existing COFDM modulation system broadcast (mainly started in Europe, Canada, and Australia excluding the former socialist sphere) that is also mounted on mobile objects such as automobiles. It is the block diagram which showed the structure of the tuner part of a machine (for example, refer patent document 1). This example belongs to the category of digital audio radio using the COFDM modulation system, but the tuner section is not much different from conventional amateur radio equipment or analog NTSC / PAL / SECAM television, FM, AM radio, The objective is to amplify the C / N of the desired signal received by the antenna without losing it as much as possible, and send it to the demodulator as the signal processor at the subsequent stage.

  In FIG. 2, first, electric power induced in an active antenna element (not shown) is taken in from an RF input terminal 45, and L-Band (1452-1492 MHz) and BandIII (175-175) used in an existing DAB by the duplexer 1. 240 or 250 MHz) are extracted and sent to the L-band gain variable RF amplifier 25 and the combiner 2, respectively. At this time, a DC current is supplied from the antenna DC supply terminal 35 via the low-pass filter 37 to the active antenna element. In the figure, 35 is an antenna DC supply terminal, and 37 is a low-pass filter.

  The signal sent to the L-Band gain variable RF amplifier 25 is amplified here, and then output from the L-Band local oscillator 27 controlled by the L-Band PLL block 30 in the L-Band mixer 26. Are mixed to form an RF signal in the Band III frequency band, and further sent to the first tracking filter 3 via the combiner 2. On the other hand, the output signal from the L-Band mixer 26 is envelope-detected by the AGC block 31, and the DC signal controls the gain of the L-Band gain variable RF amplifier 25 so that the frequency band of the L-Band is controlled. An AGC loop for controlling the input level of the RF signal to be optimum is formed.

  The BandIII RF signal sent to the combiner 2 was sent to the first tracking filter 3 (many of which the single-tuning type is used) and subjected to band limitation, and then amplified by the BandIII gain variable amplifier 4. Thereafter, the second tracking filter 5 limits the band again, and the signal is sent to the first mixer 6.

  The RF signal band-limited by the second tracking filter 5 was mixed by the first mixer 6 with the DC signal generated by the PLL block 10, the low-pass filter 15, the RF stage local oscillator 7, and the buffer amplifier 9. Thereafter, the first IF signal is sent to the first IF amplifier 12. The DC signal generated for controlling the oscillation frequency of the RF stage local oscillator 7 is also applied to the first tracking filter 3 and the second tracking filter 5 of the RF stage, and the center frequency of the pass band is obtained. It is also used to control.

  The signal down-converted to the first IF frequency is amplified by the first IF amplifier 12 and then narrowed by the first IF bandpass filter (fixed type) 13 as compared with the processing in the RF stage. Limited bandwidth. The first IF frequency signal subjected to the band limitation is amplified again by the second IF amplifier 14, passes through the attenuator 16, and is then sent to the second mixer 17.

  On the other hand, the signal down-converted by the first mixer 6 is extracted by the RF stage AGC block 11 where it is subjected to envelope detection to become a DC signal, which is applied to the gain variable RF amplifier 4. As a result, an AGC loop is built and the gain of the RF signal is adjusted.

  Further, the second mixer 17 mixes the input RF signal and a fixed frequency signal generated by the combination of the crystal 20 and the local oscillator 32, down-converts a certain frequency, and performs the second conversion. The IF signal is input to the second IF stage AGC block 18, the RSSI block 19, and the second IF amplifier 22. The IF signal is extracted by the IF stage AGC block 18 and subjected to envelope detection to become a DC signal. When the signal is applied to the attenuator 16, another AGC loop is formed, The gain of the IF signal 2 is adjusted.

  After the signal sent to the second IF amplifier 22 is amplified, the signal is subjected to the final narrowband limitation by the second IF bandpass filter (fixed type) 23 in the next stage, and the second IF amplifier 24 Amplified to a signal level suitable for the input range of the demodulator not shown, and this is sent out from the IF output terminal 40 to the demodulator as an analog baseband signal of the receiver.

  On the other hand, the second IF signal sent out from the second mixer 17 is also applied to an RSSI (Received Signal Strength Detector) block 19, subjected to envelope detection with a small time constant, and then passed through a low-pass filter 41. The high-frequency component is removed, and it is output from the RSSI output terminal 42 as an RSSI signal required by the subsequent demodulator at the initial stage of synchronization (timing synchronization with the burst signal) via the buffer amplifier 21.

In addition, the communication terminal with the external system controller has, for example, three terminals (DATA 36, CLOCK 37, LOCK 38) for controlling the N value of the PLL block 10 and recognizing the PLL lock in the I2C (Isquare Sea) bus. An AFC terminal 39 is provided for fine frequency tuning from the subsequent demodulator.
JP 11-46154 A (page 5-6, FIG. 1)

  However, in the conventional COFDM modulated signal receiver described above, (1). It was necessary to provide a receiver (tuner) separately for each broadcast wave to be received. (2). Since the control voltage of the voltage controlled local oscillator (VCO) was used to control the center frequency of the tracking filter in the RF stage, it is difficult to obtain ideal tracking, and man-hours on the production / manufacturing line during mass production・ A lot of time was spent. (3). Since a device with a fixed bandwidth IF filter was used, a single IF stage configuration could not cope with receiving broadcast waves with different bandwidths. (4). Since the input / output impedance between the RF stage bandpass filter and RFAmp has a frequency deviation, depending on the reception frequency, impedance matching may be lost, resulting in filter selectivity characteristics, RFAmp noise figure, and power gain characteristics. Degradation occurred, and reception sensitivity and frequency selectivity characteristics were easily damaged depending on the reception frequency.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a single tuner and a single IF stage configuration, tracking performance, filter selectivity characteristics, RF amplifier noise figure, An object of the present invention is to provide a COFDM modulated signal receiver capable of ensuring basic receiver performance such as power gain characteristics, reception sensitivity, frequency selectivity characteristics, and received information quality.

  In order to achieve the above object, the present invention includes a Hi-BAND stage, an RF stage, and an IF stage, thereby receiving a COFDM modulated wave of a desired channel and receiving it as an analog baseband signal to a demodulator. A double-tuned passive filter is used as a tracking filter of the RF stage, and two poles of the double-tuned filter are each controlled by independent DC control, and the DC control voltage for this purpose is applied to a plurality of D / A. It is generated by a converter.

  In addition, the present invention is a COFDM modulated signal receiver that includes a Hi-BAND stage, an RF stage, and an IF stage to receive a COFDM modulated wave of a desired channel and output it as an analog baseband signal to a demodulation unit. A passively tunable filter with variable bandwidth is used as the band limiting filter of the IF stage, and the two poles of the double tuned filter are each controlled by independent DC control, and a plurality of DC control voltages are used for this purpose. It is generated by a D / A converter.

  The present invention is also characterized in that a controllable impedance matching circuit is provided on the input / output side of the RF amplifier, and the impedance matching of the input / output of the RF amplifier is changed according to the reception frequency.

  As described above, in the COFDM modulated signal receiver of the present invention, by using the variable bandwidth tuning filter for the band limiting filters of the RF stage and IF stage of the COFDM modulated signal receiver, and by providing an impedance matching circuit that can be controlled in the RF stage, Receiver basics such as one tuner, one IF stage configuration, tracking performance, filter selectivity characteristics, receiver noise figure, power gain characteristics, reception sensitivity, frequency selectivity characteristics, and received information quality Performance can be ensured.

According to the present invention, a double-tuned passive filter is used as a tracking filter for the RF stage and the IF stage, and the double-tuned two poles are each controlled by independent DC control. When a COFDM modulated signal (1.536 MHz for DAB, approximately 6 MHz for terrestrial digital television) is received with a relatively large ratio of the desired reception bandwidth by being generated by the A / A converter, oscillation of the local oscillator Since the tuning voltage in the PLL is not used to control the frequency, the passband characteristic of the tracking filter is sacrificed, or the oscillation purity of the output signal of the local oscillator generated due to the importance of the characteristic of the tracking filter is sacrificed. This is eliminated because each can be designed independently.
When receiving a COOFDM-modulated signal with a relatively large desired reception frequency bandwidth relative to the reception frequency, reception of the matching degree of impedance matching between the passive circuit tracking filter and RF amplifier composed of inductors and capacitors The frequency deviation cannot be ignored as reception performance, and the main factors include passband characteristics and pass loss in multiple tracking filters, noise figure degradation in RF amplifier and increase in power gain frequency deviation, etc. A controllable impedance matching circuit is provided on the input / output side of the RF amplifier, and by changing the impedance matching of the input / output of the RF amplifier according to the reception frequency, the passband characteristics in a plurality of tracking filters And passage loss, degradation of noise figure in RF amplifier Such as an increase of the frequency deviation of the power gain can be prevented.
When dividing the frequency of the reference oscillator for creating the phase comparison frequency inside the PLL loop, the frequency of the local oscillator is divided by two parts, so that the quality of the oscillation purity of the local oscillator, the receiver sensitivity, the received signal Degradation of information quality can be prevented.
By having a band limiting filter (double tuning) that can control the bandwidth at the IF stage, for example, one tuner can be used for each VHF channel of FM radio, DAB, and TV that has a common range in the reception frequency band. It is possible to prevent having a plurality of receivers and RF modules.
By providing a controllable impedance matching circuit between the tracking filter and RFAmp in the RF stage, the receiver performance (noise figure, power gain) and anti-adjacent interference are the basic performance of the receiver due to the difference in reception frequency. It is possible to prevent the occurrence of device deterioration of characteristics (frequency selectivity characteristics).
Since the control of the RF stage tracking filter is programmable and the device for generating a DC voltage is a D / A converter, an effect of reducing characteristic variations during mass production can be expected.
By providing a plurality of types of demodulation units (for example, an AM radio detection circuit, an FM radio demodulation circuit, an NTSC / PAL demodulation circuit, an ADC for digital modulation demodulation) at the subsequent stage of the receiver, a modulation method other than COFDM It also has expandability that allows demodulated signal processing of broadcast signals.
The receiver having this configuration can have a signal processing operation required for Stationary (accompanying reception type) and mobile (mobile reception type) in one unit.

  1 tuner, 1 IF stage configuration, tracking performance, filter selectivity characteristics, RF amplifier noise figure, power gain characteristics, receiver sensitivity, frequency selectivity characteristics, receiver information quality, etc. The purpose of ensuring the performance is realized by using a variable band tuning filter for the band limiting filters of the RF stage and IF stage of the COFDM modulated signal receiver and providing an impedance matching circuit that can be controlled in the RF stage.

  FIG. 1 is a block diagram showing a configuration example of a COFDM modulated signal receiver according to an embodiment of the present invention. The COFDM signal receiver includes a duplexer 1, a combiner 2, a second band RF stage 1st double-tuned tracking filter 3, a second band RF amplifier preceding impedance matcher 4, and a second band gain variable. RF amplifier 5, second band gain continuously variable RF amplifier latter impedance matcher 6, second band RF stage 2nd double-tuned tracking filter 7, first band RF stage 1st double-tuned tracking Filter 8, impedance matching unit 9 before the first band RF amplifier, variable RF amplifier 10 with continuous gain of the first band, impedance matching unit 11 after the first band RF amplifier, RF stage 2nd double-tuned tracking filter 12, second band 1st mixer 13, first band st mixer 14, first band 1st local oscillator 15, second band 1st local oscillator 16, first band 1st local oscillator buffer amplifier 17, second band 1st local oscillator buffer amplifier 18, RF stage first PLL block (phase comparator) 19, RF stage AGC block (envelope detection) 20, first 1st IF Amp 21, 1st IF double-tuned bandpass filter 22, second 1st IF Amp 23, V-I conversion Amplifier 24, attenuator 25, 2nd mixer 26, IF stage AGC block (envelope detection) 27, 2nd IF band pass filter 28, fixed band pass filter 29, multiplier 30, first 2nd IF Amp 31, RSSI generator 32, low pass filter 33, buffer amplifier 34, second 2nd IF gain Variable Amp 35, other Hi Band AGC block (envelope detection) 36, other Hi Band gain variable RF Amp 37, band down converter mixer 38, other Hi Band band local oscillator 39, low pass filter 40, buffer amplifier 41, PLL block 42 for down converter, low pass filter 43, band pass filter 44, VCTCXO (voltage controlled temperature self-compensation reference crystal oscillator) 45, collective D / A converter 46, antenna connection terminal 47, DC for active antenna Supply terminal 48, DATA input terminal 49, CLOCK input terminal 50, PLL LOCK status output terminal (example 49.-51 .: "I2Cbus") 51, AFC control terminal 52, RSSI output terminal 53, IF OUT (analog)・ Baseband output terminal 54, Fine AGC control terminal 55, CLOCK input terminal 56, DATA input terminal 57, GND pin 58, and is configured with a low-pass filter 59.

  Next, the operation of the present embodiment will be described. First, power induced in an active antenna element (not shown) is taken in from the RF input terminal 47, and the duplexer 1 uses two L-Band (1452 to 1492 MHz) and BandIII (175 to 240 or 250 MHz) used in the existing DAB. The band is extracted and sent to the first band RF stage 1st double-tuned tracking filter 8, combiner 2, other Hi Band AGC block (envelope detection) 36, and other Hi Band gain variable RF Amp 37. . At this time, a DC current is supplied from the active antenna DC supply terminal 48 to the antenna element via the low-pass filter 43. In addition, as a broadcasting system that is currently used in the receiver for COFDM modulation broadcasting targeted in this embodiment, “DAB” (: “ETS300401”), “DVB”, ““ terrestrial digital television ” 1-segment reception mode for mobile reception (reception mode for mobile reception including in-vehicle use and mobile phone features) is also raised. Is already in operation.

  First, the RF amplifiers 5 and 10 with variable gain provided for two bands, the RF stage of the second band 1st double-tuned tracking filter 3 provided before and after the stage, and the RF of the second band A stage 2st double-tuned tracking filter 7, a first band RF stage 1st double-tuned tracking filter 8, and a first band RF stage 1st double-tuned tracking filter 12 are provided to generate a 1stIF signal. 2st band 1st local oscillators 15 and 16 that emit mixed signals, and 1st mixers 13 and 14 that mix the received signal and the output signal of the local oscillator provided for each band. Down converted.

  Further, the third band having a higher frequency is sent to another Hi Band gain variable RF Amp 37 by the duplexer 1 (the official name is a triplexer in this proposal), and the other Hi Band AGC block 36 is transmitted. Depending on the closed loop, the signal is amplified with the optimum amplification level of the received signal level and sent to the combiner 2. The tracking filters 3, 7, 8, and 12 of each band controlled by the tuning frequency are not DC voltage signals for frequency control of a conventional local oscillator, but DC voltages generated by the collective D / A converter 46. It is controlled using a signal. Each tracking filter 3, 7, 8, 12 uses a double-tuned type, and the two poles are separately controlled by an independent D / A converter inside the collective D / A converter 46. Thus, not only the pass center frequency but also the pass bandwidth characteristic can be varied.

  Similarly, the impedance matching units 4, 6, 9, and 11 of the two RF stage gain variable RF Amps 5 and 10 are also subjected to voltage control from independent D / A converters to correct the impedance matching of the input and output of the variable gain RF Amp. To do. Therefore, the frequency-deviation of Power Gain and noise figure (: NF) due to the reception frequency is suppressed. Further, as an additional effect, the impedance matching of the passive double-tuned tracking filters before and after that does not collapse, so that the deterioration of the filter selectivity characteristics and the pass loss characteristics can be reduced.

  The tracking filter control signal and the impedance matching circuit control signal are generated based on processing from the system controller. By processing the control signal for the tracking filter and the signal for the impedance matching unit from the system controller, the two-tuned tracking filters 3, 7, 8, 12 in the RF stage and the double-tuned bandpass filter 22 in the 1st IF stage By controlling the two poles independently, reception of broadcast waves having different occupied bandwidths can be handled by a program in the system controller unit or table format data stored in the ROM.

Here, the 1st IF (: first intermediate frequency) signal generating means of the COFDM modulated broadcast receiver of the present embodiment is an N value (programmable program) that is sent to the PLL block 19 of the RF stage to be tuned by the system controller. By sending an integer divider value for the divider, the oscillation frequencies of the 1st local oscillators (VCO) 15 and 16 are stabilized with high accuracy, and the 1st IF signal is generated by the signals and the 1st mixers 13 and 14.

  The 2ndIF (: first intermediate frequency) signal generation means does not include a PLL-controlled local oscillator, and based on a frequency relationship designed as a frequency synthesizer, the frequency of the VCTCXO 45 is multiplied, and the bandpass filter 29 essential components Using the signal from which 2 is removed as a mixed signal, a 2dIF signal is generated at 2nd26.

  Down-converting block (combiner, Hi Band AGC block 36, Hi Band gain variable Amp 37, band down converter mixer 38, Hi band local oscillator 39 controlled by PLL polyimide resin) for other Hi Band RF signals Further, the output signal is passed through a common circuit in the signal processing line of the RF stage, down-converted to the same 1st and 2nd IF frequencies, and subjected to the same signal processing except for the frequency selection processing.

  A Hi Band down-converter must be built in for the desired reception frequency against the difference in specifications of transmission frequency band and specific modulation bandwidth such as existing FM radio, DAB, DVB, and terrestrial digital television. On the other hand, the modulated bandwidth can be dealt with by varying the pass bandwidth with the RF stage, the 1st IF filter 22, and the 2nd IF filter 28. In addition, other demodulation units (for example, AM radio detection circuit, FM radio demodulation circuit, NTSC demodulation circuit, ADC for digital modulation demodulation, etc.) are provided after the receiver to receive broadcast signals other than COFDM.・ Scalability for demodulation is also provided.

The reference signal for phase comparison of the PLL block 42 for the down converter and the PLL block 19 of the RF stage and the output signal from the multiplier 30 obtained by multiplying the signal of the VCTCXO 45 itself are applied to the AFC control terminal 52 as the VCTCXO 45 which is the system frequency reference. Since a finer and more continuous frequency tuning can be executed with the control signal from the demodulator at the subsequent stage of the DC signal to be processed, it is possible to cope with a fading phenomenon including a Doppler shift under Rayleigh fading at the time of mobile reception.

  The DC voltage signal from the collective D / A converter block 46 to the four tracking double-tuned filters 3, 7, 8, 12 and the four impedance matchers 4, 6, 9, 11 in the RF stage Data managed as table-type data in a memory or the like in the provided system controller is sent via the communication terminals of the CLOCK input terminal 56, the DATA input terminal 57, and the GND terminal 58, and the analog DC voltage value is determined from the data information. Can be obtained by converting to.

  The double-tuned bandpass filters 3, 7, 8, 12, 22, and 28 in the RF stage, 1stIF stage, and 2ndIF stage have two resonance points called poles, and the resonance points on the frequency axis are variable. Is performed by varying the DC voltage applied to the varicap diode, which is a capacitive element constituting the filter.

  The impedance matching devices 4, 6, 9, and 11 placed before and after the gain variable RF amplifiers 5 and 10 in the RF stage are also composed of a plurality of inductors and capacitors, and the capacitor components of these are made using varicap diodes. By being configured, control is performed by the DC voltage signal generated by the collective D / A converter 46 in accordance with the reception frequency so that good impedance matching can be obtained when the reception frequency changes.

As a control signal for frequency tuning from the system controller, there is a communication bus (ex. “I ² Cbus” * actually composed of three other GND lines) such as a CLOCK input terminal 50 and a DATA input terminal 49. N value [: Divider value of programmable divider] is obtained, and each PLL loop (Hi Band, first RF band, second RF band) is locked, and oscillation of each local oscillator 15, 16, 39 is performed. The frequency is locked.

  Regarding the operation of AGC, in the first mixer of two RF bands, the signal down-converted to 1st IF is envelope-detected by the RF stage AGC block 20 and converted into a DC voltage signal proportional to the amplitude level of the signal, A gain control signal is applied to the gain variable RF amplifiers 5 and 10 of the two RF bands, and an AGC loop is formed. As an example of the variable gain RF amplifier, a method of varying the power gain by applying the signal to the second gate of the dual gate FET is also an example.

  Although the principle is the same for the AGC operation in the IF stage, since the gain of the IF stage is normally designed to be as high as several tens of dB, it is not sufficient to change only the gain of the first 1st IF Amp 21, and the VI conversion amplifier 24 An operation for gaining attenuation by giving a control signal of DC current through the attenuator 25 (in many cases, a PIN diode is used) is also performed in a region other than weak input reception in a weak electric field.

  In the 2nd IF of the final stage, the demodulator of the subsequent stage matches the level of the desired signal to a level suitable for signal processing (detection, AD conversion, AD conversion and FFT processing, etc.), unnecessary noise components and distortion components outside the band 2nd IF bandpass filter 28 performs final out-of-band component removal filtering, which is sufficiently amplified by two stages of 2ndIF Amps 31 and 35 and output from IFOUT 54 (to the demodulator). Also, the gain variable second 2ndIFAmp 35 that is the final amplification unit is applied with a DC control signal from the demodulation unit via the FineAGC control terminal 55, and fine input level adjustment to the demodulation unit is performed. On the other hand, the output from the first 2ndIFAmp 31 is also sent to the RSSI generator 32, subjected to envelope detection with a small time constant, output to the low-pass filter 33, and after removing high frequency components there, the buffer amplifier 34 And output from the RSSI output terminal to the demodulator. Note that the RSSI signal generated by this receiver is mainly used as a trigger for temporal synchronization of the desired received signal when the demodulator at the subsequent stage synchronizes.

  According to the present embodiment, the tracking filters 3, 7, 8, and 12 use a double-tuned type, and separate the two poles into independent D / A converters inside the collective D / A converter 46. Therefore, not only the pass center frequency but also the pass bandwidth characteristic can be made variable by controlling.

  Similarly, the two RF stage gain variable RF Amps 5 and 10 and the impedance matching units 4, 6, 9, and 11 around the same are also subjected to voltage control from independent D / A converters, and the impedance matching of the input and output of the variable gain RF Amps. Correct. Therefore, the deviation of Power Gain and noise figure (: NF) due to the reception frequency is suppressed. Furthermore, as an additional effect, the impedance matching of the passive double-tuned tracking filter before and after that does not collapse, so that it is possible to reduce the deterioration of the filter selectivity characteristic and the pass loss characteristic.

  The tracking filter control signal and the impedance matching circuit control signal are generated based on processing from the system controller. By processing the control signal for the tracking filter and the signal for the impedance matching unit from the system controller, the two-tuned tracking filters 3, 7, 8, 12 in the RF stage and the double-tuned bandpass filter 22 in the 1st IF stage By making the control of the two poles independent, reception of broadcast waves having different occupied bandwidths can be dealt with by a program in the system controller unit or table format data stored in the ROM.

  In addition, other demodulation units (for example, AM radio detection circuit, FM radio demodulation circuit, NTSC demodulation circuit, ADC for digital modulation demodulation, etc.) are provided after the receiver to receive broadcast signals other than COFDM.・ Scalability for demodulation can be provided.

  Further, the reference signal for phase comparison of the PLL block 42 for the down converter and the PLL block 19 of the RF stage, and the output signal from the multiplier 30 obtained by multiplying the signal of the VCTCXO 45 itself are connected to the VCTCXO 45 which is the frequency reference of the system by the AFC control terminal 52. Since the DC signal applied to can be executed with a control signal from the demodulator at the subsequent stage, finer and continuous frequency tuning can be executed, it is possible to cope with the Rayleigh fading phenomenon including Doppler shift at the time of mobile reception.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can implement also with another various form in a concrete structure, a function, an effect | action, and an effect.

It is the block diagram which showed the structural example of the COFDM modulation signal receiver which concerns on one embodiment of this invention. It is the block diagram which showed the structural example of the tuner part of the receiver of DAB which is the conventional COFDM modulation system broadcast

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Duplexer, 2 ... Combiner, 3 ... Second band RF stage 1st double-tuned tracking filter, 4 ... Second band RF amplifier front stage impedance matching device, 5 ... Second Band gain variable RF amplifier, 6... Second band gain continuously variable RF amplifier latter impedance matcher, 7. Second band RF stage 2nd double-tuned tracking filter, 8. RF band 1st double-tuned tracking filter for the first band, 9... First impedance amplifier for the first band RF amplifier, 10... First band gain continuous variable RF amplifier, 11. Impedance matcher after the band RF amplifier, 12... 1st band RF stage 2nd double-tuned tracking filter, 13. 14: First band 1st mixer 15: First band 1st local oscillator 16: Second band 1st local oscillator 17: First band 1st local oscillator buffer Amplifier 18 ... Buffer amplifier of 1st local oscillator of the second band, 19 ... RF stage PLL block (phase comparator), 20 ... RF stage AGC block (envelope detection), 21 ... First 1stIFAmp, 22... 1stIF double-tuned band-pass filter, 23... 2nd 1stIFAmp, 24... VI conversion amplifier, 25. (Envelope detection), 28 ...... 2nd IF bandpass filter, 29 ... fixed bandpass filter, 30 ... multiplier, 31 ... first 2nd FAmp, 32... RSSI generator, 33... Low pass filter, 34... Buffer amplifier, 35... Second 2nd IF gain variable Amp, 36 .. Other Hi Band AGC block (envelope detection), 37. Other Hi Band gain variable RF Amp, 38 ...... Band down converter mixer, 39 ...... Other Hi Band band local oscillator, 40 ... Low pass filter, 41 ... Buffer amplifier, 42 ... Down converter PLL block , 43... Low pass filter, 44... Band pass filter, 45... VCTCXO (voltage controlled temperature self-compensation reference crystal oscillator), 46... Collective DA converter, 47. DC supply terminal, 49 ... DATA input terminal, 50 ... CLOCK input Power terminal 51... PLL LOCK status output terminal 52... AFC control terminal 53... RSSI output terminal 54... IF OUT (analog baseband output terminal) 55 55 Fine AGC control terminal 56 ... CLOCK input terminal, 57 ... DATA input terminal, 58 ... GND terminal, 59 ... Low-pass filter.

Claims (7)

A COFDM modulated signal receiver that includes a Hi-BAND stage, an RF stage, and an IF stage to receive a COFDM modulated wave of a desired channel and output it as an analog baseband signal to a demodulation unit,
A double-tuned passive filter is used as the tracking filter of the RF stage, and two poles of the double-tuned filter are each controlled by independent DC control, and a DC control voltage for that purpose is generated by a plurality of D / A converters. A COFDM modulated signal receiver. A COFDM modulated signal receiver that includes a Hi-BAND stage, an RF stage, and an IF stage to receive a COFDM modulated wave of a desired channel and output it as an analog baseband signal to a demodulation unit,
A passive double-tuned filter having a variable bandwidth is used as the band-limiting filter of the IF stage, and each of the two poles of the double-tuned filter is performed by independent DC control. A COFDM modulated signal receiver generated by a D / A converter.   2. The COFDM modulation according to claim 1, wherein a controllable impedance matching circuit is provided on an input / output side of the RF amplifier, and impedance matching of the input / output of the RF amplifier is changed according to a reception frequency. Signal receiver.   3. The COFDM modulation signal receiver according to claim 1, wherein the COOF modulation signal receiver is continuously variable in accordance with a bandwidth of a broadcast receiving the RF stage and IF stage double-tuned passive filter.   2. The RF stage double-tuned passive filter tracking filter is controlled by a voltage generated by a setting to a plurality of D / A converters sent from a system controller. The COFDM modulated signal receiver described.   The control of the double-tuned passive filter tracking filter of the IF stage is controlled by a voltage generated by a setting to a plurality of D / A converters sent from a system controller. The COFDM modulated signal receiver described.   The system controller stores the type of received broadcast signal and the tuning frequency information held in a table in a memory, converts the stored information into setting values of a plurality of D / A converters in the receiver, and converts these D 7. The COFDM modulated signal receiver according to claim 5 or 6, wherein the signal is sent to a / A converter.

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