JP7249246B2 - receiver - Google Patents

Description

The present disclosure relates to a receiver having a function of filtering multi-frequency electrical signals.

A filter device is known that has a plurality of filters with different passbands, which are connected to a common terminal (for example, Patent Document 1). Patent Literature 1 discloses a configuration in which a matching circuit for impedance matching and an amplifier for amplifying a signal are connected in order after a plurality of filters (on the side opposite to the common terminal).

JP 2012-244615 A

It is desired to provide a receiving device capable of communicating electrical signals in a plurality of frequency bands with high accuracy.

A receiving device according to an aspect of the present disclosure includes an antenna that receives electrical signals in at least three or more frequency bands, an input terminal, and an output terminal, the input terminal is connected to the antenna, and the electrical signal is filtered. and an IC connected to the output terminal of the receiving module. The receiving module includes a pre-filter section connected to the input terminal side and a post-filter section connected to the output terminal side. The pre-filter section includes a first filter and a second filter connected in parallel between a first common terminal and a second common terminal. The first filter filters at least one frequency band of the electrical signal. The second filter filters more frequency bands of the electrical signal than the frequency bands filtered by the first filter, and has a fractional bandwidth wider than the fractional bandwidth of the first filter. and an adjustment unit that adjusts the delay time between the first signal that passes through the first filter and the second signal that passes through the second filter.

A receiving device according to an aspect of the present disclosure includes an antenna that receives electrical signals in at least three or more frequency bands, an input terminal, and an output terminal, the input terminal is connected to the antenna, and the electrical signal is filtered. and an IC connected to the output terminal of the reception module. The receiving module includes a pre-filter section connected to the input terminal side and a post-filter section connected to the output terminal side, wherein the pre-filter section includes a first common terminal and a second common terminal. a first filter for filtering at least one frequency band of the electrical signal, connected in parallel between the a second filter that filters and has a fractional bandwidth substantially the same as the fractional bandwidth of the first filter.

According to the above configuration, it is possible to provide a receiver that can accurately process electrical signals in a plurality of frequency bands.

1 is a schematic diagram showing the configuration of a receiving device according to a first embodiment; FIG. FIG. 2 is a schematic diagram showing a main configuration of a pre-filter device of the receiver of FIG. 1; FIG. 3 is a schematic diagram showing a configuration of a pre-filter section in FIG. 2; FIG. 4(a) is a schematic diagram showing the main part of the receiver according to the second embodiment, and FIG. 4(b) is a schematic diagram showing the bandwidth of each filter. FIG. 5(a) is a schematic diagram showing a main part of a modification of the receiver according to the second embodiment, and FIG. 5(b) is a schematic diagram showing the bandwidth of each filter. be. FIG. 11 is a schematic diagram showing the essential parts of a receiving device according to a third embodiment; FIG. 14 is a schematic diagram showing the bandwidth of each filter of the receiver according to the fourth embodiment; FIG. 8(a) is a diagram showing pass characteristics of the first filter with respect to frequency, and FIG. 8(b) is a diagram showing delay time with respect to frequency of the first filter. FIG. 9(a) is a diagram showing pass characteristics of the second filter with respect to frequency, and FIG. 9(b) is a diagram showing delay time with respect to frequency of the second filter. FIG. 10(a) is a diagram showing the pass characteristic of the dielectric filter with respect to frequency, and FIG. 10(b) is a diagram showing the delay time with respect to frequency of the dielectric filter.

Embodiments will be described below with reference to the drawings. In the following description, like "first filter 19A" and "second filter 19B", identical, similar or corresponding configurations may be denoted by different capital letters. Also, in this case, the upper case letters may be simply omitted to distinguish between the two, such as "filter 19".

From the second embodiment onwards, basically, only differences from the already described embodiments will be described. Matters not specifically mentioned may be the same as those of the already described embodiments. In the second and subsequent embodiments, the same or similar configurations as those of the already-described embodiments may be denoted by the same reference numerals as those of the already-described embodiments. Even if a configuration corresponding to (similar to) the configuration of the already described embodiment is denoted by a different code from the configuration of the already described embodiment, matters not specifically mentioned , may be similar to the configuration of the already described embodiments.

[First embodiment]
(Overall configuration of receiving device)
FIG. 1 is a schematic diagram showing the main configuration of a receiver 1 according to the first embodiment.

The receiving device 1 is configured, for example, as a device that receives radio waves and executes predetermined processing. For example, the receiving device 1 is configured by connecting an antenna 3, a receiving module 5, and an IC (Radio Frequency Integrated Circuit) 7 and BB-IC (Base Band Integrated Circuit) 9 in this order from the radio wave receiving side. It is

The antenna 3 converts received radio signals (radio waves) into electrical signals. Antenna 3 receives signals of multiple frequency bands of at least three frequency bands. In this example, the electrical signal contains four frequency bands L1-L4. The receiving module 5 amplifies the electric signal from the antenna 3, extracts an electric signal in a predetermined passband from the electric signal, and outputs the electric signal. The RF-IC 7 demodulates, frequency-downgrades, and digitizes the electrical signal from the receiver module 5, for example. The BB-IC 9 performs various processes on the signal from the RF-IC 7, for example.

The receiving device 1 may be used for various purposes, and the carrier frequency (passband frequency of the receiving module 5), baseband frequency, processing contents of the BB-IC 9, etc. may be determined according to the purpose. . For example, the receiver 1 is used in a GNSS (Global Navigation Satellite System) such as a GPS (Global Positioning System). The passband of the receiving module 5 may be set according to the GNSS standard, for example, and is 1000 MHz or more and 3000 MHz or less as an example.

In this example, the case where the RF-IC 7 and the BB-IC 9 are connected to the output side of the receiving module 5 has been described as an example, but the present invention is not limited to this. For example, an IC in which RF-IC 7 and BB-IC 9 are integrated may be used.

(Configuration of receiving module)
The receiving module 5 has an input terminal 5a and an output terminal 5b, the input terminal 5a is connected to the antenna 3, and the output terminal 5b is connected to the RF-IC 7. FIG. A separate matching circuit may be connected between the antenna 3 and the input terminal 5a.

For example, as shown in FIG. 2, the receiving module 5 has a pre-amplifier 11, a pre-filter section 13, a post-amplifier 15, and a post-filter section 17 in order from the antenna 3 side.

The pre-amplifier 11 amplifies and outputs the electrical signal input from the input terminal 5a. The pre-amplifier 11 may be configured by, for example, a so-called low noise amplifier (LNA: Low Noise Amplifier). The NF (Noise Figure) of the LNA is, for example, 0.5 dB or more and 1.5 dB or less.

The configuration of the preamplifier 11 may be similar to various known configurations. Although not shown, the preamplifier 11 has, for example, a power supply terminal, an input signal reference potential terminal, an output signal reference potential terminal, and a control terminal (for example, ON/OFF of the preamplifier 11). Although there is one input terminal in the illustrated example, there may be two. The fact that the configuration of the amplifier may be a known configuration in this way also applies to the post-stage amplifier 15 .

The pre-filter section 13 includes a plurality of (two in the illustrated example) first filters connected in parallel between the first common terminal 13a and the second common terminal 13b and connected to the output side of the pre-amplifier 11. 19A and a second filter 19B. Each filter 19 extracts and outputs a signal in a predetermined frequency band (passband) from the input electrical signal.

The first filter 19A filters the electrical signal from the antenna 3 so as to pass at least one frequency band. The second filter 19B filters the electric signal from the antenna 3 so as to pass more frequency bands than the frequency band filtered by the first filter 19A. A signal output from the first filter 19A is referred to as a first signal S1, and a signal output from the second filter 19B is referred to as a second signal S2.

The filters 19A and 19B may be configured using, for example, resonators that excite surface acoustic waves (SAW). Alternatively, the filter may be configured using an FBAR (Film Bulk Acoustic Resonator) that uses elastic waves in the thickness direction of the thin film.

The post-amplifier 15 amplifies the electrical signal input from the pre-filter section 13 side and outputs the amplified signal to the post-filter section 17 side. The post-amplifier 15 is configured by an LNA, for example, like the pre-amplifier 11 . The front-stage amplifier 11 and the rear-stage amplifier 15 may have the same configuration (the same product), or may have different configurations.

The post-filter section 17 has a post-filter 21 connected to the output side of the post-amplifier 15 . The post-filter 21 has two (first post-filter 21A, second post-filter 21B) in this example. Each post-filter 21 extracts and outputs a signal in a predetermined frequency band (passband) from the input electrical signal. The passbands of the multiple post-filters 21 are different from each other.

The number of post-filters 21 may be the same as the number of filters 19, for example. In that case, the passband of each post-filter 21 is identical to the passband of the filter 19 labeled with the same capital letter. That is, the passband of the first post-filter 21A is the same as the passband of the first filter 19A. The passband of the second post-filter 21B is the same as the passband of the second filter 19B. The filter 19 and the post-filter 21 having the same passband may have the same configuration or may have different configurations.

The first post-filter 21A and the second post-filter 21B are connected to post-amplifiers 15A and 15B, respectively. The output sides of the plurality of post-filters 21 are connected to each other, for example. Accordingly, the plurality of passband electrical signals filtered by the plurality of post-filters 21 are combined into one and input to the RF-IC 7 .

As described above, the receiving module 5 as a whole extracts signals of a plurality of passbands from the input electrical signal and collectively outputs them. At this time, the electrical signal is also amplified. Also, the amplification and extraction of the signal is done in two stages within the receiver module 5 .

The RF-IC 7 and/or BB-IC 9 includes a multiplexer (not shown), and divides the input electrical signal into multiple filters 19 (post-filter 21) in the passbands (corresponding passbands in the case of BB-IC 9, etc.). ) signals. The BB-IC 9 then executes processing for selectively using the demultiplexed signals and/or processing for jointly using the demultiplexed signals.

(Configuration of front-stage filter section)
In this example, the first filter 19A included in the pre-filter section 13 filters the first frequency band L1, and the second filter 19B filters the second to fourth frequency bands L2 to L4, respectively. A signal that has passed through the first filter 19A is called a first signal S1, and a signal that has passed through the second filter 19B is called a second signal S2.

(Adjuster 50)
In the pre-filter section 13 described above, the fractional bandwidth of the first filter 19A is narrower than the fractional bandwidth of the second filter 19B.

Thus, if the filters 19A and 19B connected in parallel to one antenna 3 capable of receiving multiple frequencies have different relative bandwidths, the delay times of the signals passing through the filters 19A and 19B are shifted. Specifically, the delay time of the signal (second signal S2) passing through the wider fractional bandwidth (filter 19B) is shorter than the other. In order to widen the relative bandwidth of the filter, the difference between the resonance and anti-resonance frequencies of the resonators (for example, SAW resonators) that make up the filter must be widened. Therefore, the delay time becomes shorter.

As a result, when processing the signals that have passed through the filters 19A and 19B, it becomes impossible to process the signals received at the same time. As a result, when performing signal processing, even if you try to analyze only direct waves, you end up analyzing multipath signals. are different, the SNR (signal-to-noise ratio) of the received signal is lowered, and accurate analysis may not be possible.

Therefore, in the present embodiment, as shown in FIG. 3, an adjustment section 50 is provided to reduce this delay time deviation. In this example, the adjustment section 50 is configured with an auxiliary filter 51 .

The auxiliary filter 51 is connected between the second filter 19B with a wide fractional bandwidth and the first common terminal b. That is, the second filter 1B and the auxiliary filter 51 are connected in series. A first filter 19A is connected in parallel with the filters 19A and 51 connected in series. With such a configuration, the second signal S2 passing through the second filter 19B passes through more filters than the first signal S1, and the delay time becomes longer accordingly. As a result, the difference in delay time between the first signal S1 and the second signal S2 is alleviated before reaching the second common terminal 13b.

Such an auxiliary filter 51 is not particularly limited as long as it can pass electrical signals in a plurality of frequency bands included in the second signal S2, but may have the same configuration as the second filter 19B, for example. In that case, the fractional bandwidth is also equivalent.

In this example, one auxiliary filter 51 is provided, but two or more may be provided.

[Second embodiment]
Next, another embodiment will be described with reference to FIG. A receiving device 1A shown in FIG. 4A differs from the receiving device 1 in that an adjusting section 50A is provided instead of the adjusting section 50 (auxiliary filter 51) shown in FIG.

In the following, only different parts will be described, and redundant descriptions of other configurations will be omitted.

In the receiver 1A, the pre-filter section 13A does not include the auxiliary filter 51. FIG. That is, it has the configuration of the pre-filter section 13 shown in FIG. In the post-filter section 17A, the first signal S1 from the first filter 19A is input to the first post-filter 21A. It is wider than the fractional bandwidth. In FIG. 4(b), the double arrow indicates the fractional bandwidth. Such a first post-filter 21A functions as the adjusting means 50A.

By widening the relative bandwidth of the first post-filter 21A, the signal is transmitted to the output terminal 5b without increasing the difference in delay time between the first signal S1 and the second signal S2, which occurs in the pre-filter section 13A. can be output.

Furthermore, the fractional bandwidth of the first post-filter 21A may be equal to or greater than the fractional bandwidth of the second filter 19B. In this case, the difference in delay time between the first signal S1 and the second signal S2 that occurs in the pre-filter section 13A can be further reduced.

In the above example, the post-filter unit 17A includes the first post-filter 21A that passes the band included in the first signal S1, and the second post-filter 21B that passes a plurality of bands included in the second signal S2. Although the case where it is configured to include is described as an example, it is not limited to this.

For example, as in the receiving device 1B shown in FIG. 5(a), the post-filter section 17B may be composed of only one post-filter 21. FIG. That is, both the first signal S1 and the second signal S2 are input to the same post-filter 21 . Such a post-stage filter 21 becomes the adjusting section 50B.

In this case, as shown in FIG. 5B, the post-filter 21 has a wider fractional bandwidth than either the first filter 19A or the second filter 19B. In FIG. 5(b), the double arrow indicates the fractional bandwidth. By providing the post-stage filter 21 having such a wide specific bandwidth, the difference in delay time between the first signal S1 and the second signal S2 generated in the pre-stage filter section 13A is not exacerbated, and the output terminal 5b, the difference in delay time between the first signal S1 and the second signal S2 can be reduced.

As such a post-filter 21, a dielectric filter or the like having a wide specific bandwidth may be used, or an LC filter configured by combining a chip inductor and a chip capacitor may be used. When these filters are used, a stable wide band filter can be realized. When the filter constituting the front-stage filter unit 13 is a SAW filter and the rear-stage filter 21 is an LC filter, only the signals in the required frequency band are transmitted by the SAW filter with high selectivity and high Q value. , the delay time can be effectively alleviated.

In addition, since the delay time can be adjusted without increasing the number of filters through which the electrical signal received by the antenna 3 passes, it is possible to provide the receivers 1A and 1B with little loss.

[Third embodiment]
Next, a receiver 1C according to another embodiment will be described with reference to FIG. FIG. 6 differs from the above-described embodiment in that an adjustment section 50C is provided instead of the adjustment sections 50, 50A, and 50B.

The adjuster 50C is provided in the RF-IC7. The RF-IC 7 has individual filters 27 corresponding to each of a plurality of frequency bands included in the electrical signal received by the antenna 3 capable of multi-frequency reception. In this example, individual filters 27a to 27d corresponding to frequency bands L1 to L4 are provided.

Then, the frequency band (for example, L1) included in the first signal S1 is input to the individual filter 27a, and the frequency bands (L2 to L4) included in the second signal S2 are input to the individual filters 27b to 27d, respectively.

Here, the adjustment unit 50C is configured by increasing the number of stages in which the individual filters 27b to 27d are connected in series as compared to the number of stages in which the individual filter 27a is connected in series. In this example, the individual filter 27a has one stage, whereas the individual filters 27b to 27d are connected in series in multiple stages (two stages in the example shown). With such a configuration, it is possible to increase the delay time of the electrical signal in the frequency band included in the second signal S2, thereby alleviating the difference in delay time between the first signal S1 and the second signal S2. can be made

Incidentally, such individual filter 27 may be a filter using a SAW resonator in order to increase the Q value.

[Fourth Embodiment]
In the above example, it is assumed that a delay time occurs in the filter 19 of the pre-filter section 13, and means for alleviating the delay time that has occurred has been examined. It may be configured to suppress the occurrence of delay time between the first signal S1 and the second signal S2.

In this case, the adjustment unit 50D may be configured such that the fractional bandwidths of the first filter 17A and the second filter 17B are substantially the same as shown in FIG. 7, for example. In FIG. 7, the double arrow indicates the fractional bandwidth. In other words, the first filter 17A has a wider fractional bandwidth than the originally required fractional bandwidth. As a result, the delay times of the first signal S1 and the second signal S2 can be substantially the same.

In the above example, the bands of the first filter 17A and the second filter 17B are adjusted so as not to overlap.

(Effect verification)
Here, FIG. 8(a) shows the transmission characteristic of the first filter in which one frequency band is included in the passband, and FIG. 8(b) shows the delay time in the first filter. The first filter is a SAW filter with a fractional bandwidth of 4.7%.

In FIG. 8A, the horizontal axis indicates frequency (unit: MHz), and the vertical axis indicates transmission characteristics (dB). In FIG. 8B, the horizontal axis indicates frequency (unit: MHz) and the vertical axis indicates delay time (ns).

Similarly, FIGS. 9(a) and 9(b) show the characteristics of the second filter whose passband includes three frequency bands. The second filter is a SAW filter with a fractional bandwidth of 13.8%.

Also, FIG. 10 shows the same characteristics as FIGS. 8 and 9 for the characteristics of an LC filter composed of a dielectric covering all of the frequency bands L1 to L4.

As shown in FIGS. 8 and 9, it is confirmed that the wider the fractional bandwidth, the shorter the delay time. On the other hand, comparing FIGS. 8 and 9 with FIG. 10, it can be seen that the attenuation characteristics and loss of the pass characteristics are extremely good by dividing the frequency bands L1 to L4 into two or more and performing signal processing using filters using SAW resonators. I was able to confirm that it can be done.

As described above, according to the receiving apparatus according to the present embodiment, it is possible to simultaneously process multiple frequency bands with high characteristics and reduce the influence of delay time.

Therefore, configurations unrelated to filtering can be changed as appropriate. For example, the number of post-amplifiers 15 may be reduced to reduce size, power and/or cost. Further, in the receiving device 1, the post-filter 21 may be provided individually corresponding to each of the frequency bands L1 to L4.

REFERENCE SIGNS LIST 1 receiver, 5 receiver module, 13 pre-filter device (filter device), 19 pre-filter, 23 (first) common terminal, B1 to B4 passband.

Claims (9)

An antenna that receives electrical signals in at least three or more frequency bands;
a receiving module comprising an input terminal and an output terminal, the input terminal being connected to the antenna and filtering the electrical signal;
an IC connected to the output terminal of the receiving module;
The receiving module includes a pre-filter section connected to the input terminal side and a post-filter section connected to the output terminal side,
The pre-filter unit is connected in parallel between a first common terminal and a second common terminal,
a first filter filtering at least one frequency band of the electrical signal;
a second filter that filters more frequency bands than those filtered by the first filter in the electrical signal and has a fractional bandwidth wider than the fractional bandwidth of the first filter;
an adjustment unit that adjusts the delay time between the first signal that passes through the first filter and the second signal that passes through the second filter ,
The adjustment unit is a filter positioned after the second filter, and the second filter has a wider fractional bandwidth than the first filter, and the second filter When the delay time of the second signal immediately after passing through the first filter is shorter than the delay time of the first signal immediately after passing through the first filter, the difference between the delay times is not increased. and a filter that adjusts the delay time of at least one of the second signal
receiving device. 2. The receiving device according to claim 1, wherein said filter of said adjustment unit has an auxiliary filter between said second filter and said second common terminal. 3. The receiver of claim 2, wherein said auxiliary filter has substantially the same fractional bandwidth as said second filter. The filter of the adjustment section has a third filter through which the first signal passes, and the fractional bandwidth of the third filter is wider than the fractional bandwidth of the first filter. 2. The receiving device according to claim 1. 5. The third filter according to claim 4, wherein the first signal and the second signal commonly pass through, and the filter has a fractional bandwidth wider than the fractional bandwidths of the first filter and the second filter. Receiving device as described. The first filter and the second filter are filters using surface acoustic waves,
6. The receiver according to claim 5, wherein said third filter is a dielectric filter. each of the ICs includes an individual filter corresponding to each frequency band of the electrical signal;
The filter of the adjustment unit has the individual filter, and the individual filter filters the frequency band included in the second signal more than the filter corresponding to the frequency band included in the first signal. 2. The receiving device according to claim 1 , wherein the number of stages is large . An antenna that receives electrical signals in at least three or more frequency bands;
a receiving module comprising an input terminal and an output terminal, the input terminal being connected to the antenna and filtering the electrical signal;
an IC connected to the output terminal of the receiving module;
The receiving module includes a pre-filter section connected to the input terminal side and a post-filter section connected to the output terminal side,
The pre-filter unit is connected in parallel between a first common terminal and a second common terminal,
a first filter filtering at least one frequency band of the electrical signal;
a second filter that filters more frequency bands than the frequency bands filtered by the first filter in the electrical signal and has a fractional bandwidth that is approximately the same as the fractional bandwidth of the first filter. Device. 9. Any one of claims 1 to 8, wherein the receiving module comprises a pre-amplifier between the input terminal and the first common terminal, and a post-amplifier between the first filter and the second filter. Receiving device as described.

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