JP2019134248A - Radio equipment - Google Patents

Abstract

To provide radio equipment capable of making followability and stability compatible for the input signal level, in digital variable gain amplifier.SOLUTION: Radio equipment has a variable gain amplifier for amplifying an input signal variably, an AD conversion part for converting the input signal, outputted from the variable gain amplifier, from analog signal to digital signal, a level controller for controlling the signal level of the converted input signal, and a feedback section performing feedback control for the level controller. The feedback section has a detector, a logarithmic conversion part, a correction part, a comparator, a change amount calculation part, a control value calculation part, and a feedback control part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wireless device.

  The front end of the wireless device incorporates a variable gain amplifier (variable gain amplifier) that amplifies the received signal while changing the gain. In such a variable gain amplifier, there are mainly two types of amplifiers, a digital variable gain amplifier and an analog variable gain amplifier.

  The digital variable gain amplifier (digital variable gain amplifier) can adjust the gain discretely by a digital adjustment method. The adoption of such a digital variable gain amplifier in the front end portion of the wireless device means that the digital variable gain amplifier has a smaller circuit mounting area than the analog variable gain amplifier (analog variable gain amplifier), and has a component. Since the number of points is small, it is easy to integrate into one device, which is effective for downsizing and cost reduction of the wireless device.

  For example, variable gain amplifiers disclosed in Patent Documents 1 to 3 below can be cited as examples of variable gain amplifiers that amplify signals while changing gain.

JP 2003-152540 A JP 2007-166588 A JP-A-8-288888

  As described above, since the digital variable gain amplifier (digital variable gain amplifier) has a discrete gain adjustment, there is an adjustment unit that is the minimum adjustable width. Therefore, in an integrated device equipped with a digital variable gain amplifier, the adjustment unit tends to increase depending on the device process and the like. As a result, the digital variable gain amplifier has a larger adjustment unit than the analog variable gain amplifier (analog variable gain amplifier) capable of linearly adjusting the gain, and therefore the received signal level fluctuates due to the influence of interference waves. It is difficult to adjust following the fluctuation in an environment where the temperature is severe. Further, in the above environment, it is difficult for the digital variable gain amplifier to converge and stabilize the level of the amplified signal, and as a result, the reception performance of the radio apparatus using the digital variable gain amplifier is deteriorated.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to achieve both a tracking capability and stability with respect to a received signal level in a digital variable gain amplifier (digital variable gain amplifier). It is an object of the present invention to provide a new and improved wireless device that can be implemented.

  In order to solve the above problems, according to an aspect of the present invention, a variable gain amplifier that variably amplifies a received signal, and an AD conversion that converts the received signal output from the variable gain amplifier from an analog signal to a digital signal A level control unit that controls a signal level of the converted received signal, and a feedback unit that performs feedback control on the level control unit, wherein the feedback unit is configured to output the converted digital signal. A detection unit for detecting a signal level, a logarithmic conversion unit for logarithmically converting the detected signal level, and adding a feedback control value corresponding to a previously received preceding received signal to the conversion result of the logarithmic conversion A correction unit that corrects the logarithmically converted signal level to obtain a correction signal level, and the correction signal level and the reference signal level. A comparison unit that obtains a comparison result, a change amount calculation unit that calculates a change amount from a difference between the comparison result and the comparison result corresponding to the preceding received signal processed earlier, and the change A difference between the amount and the control unit of the variable gain amplifier is calculated with the control unit as an upper limit, and based on a difference between the control result calculation unit for obtaining the feedback control value, and the comparison result and the feedback control value Thus, a wireless device is provided that includes a feedback control unit that performs feedback control of the level control unit.

  The change amount calculation unit includes a delay unit that obtains the comparison result corresponding to the preceding received signal processed one processing unit ahead of the received signal, and the comparison result corresponding to the comparison result and the preceding received signal. And a subtractor that calculates the amount of change from the difference between.

  The control value calculation unit may obtain the feedback control value by subtracting a control unit of the variable gain amplifier from an absolute value of the change amount.

  The feedback control unit is a numerical value equal to or less than the control unit with respect to the difference between the comparison result and the feedback control value so that the difference between the comparison result and the feedback control value is an integral multiple of the control unit. The variable gain amplifier may be feedback-controlled based on the difference subjected to the truncation process.

  The feedback unit may further include an average processing unit that performs an average process on the comparison result from the comparison unit and outputs the result to the change amount calculation unit and the feedback control unit.

  The variable gain amplifier may be a digital variable gain amplifier that adjusts the gain discretely.

  The wireless device may further include a demodulation processing unit that demodulates the converted digital signal.

  The variable gain amplifier, the AD conversion unit, and the level control unit may be formed on one semiconductor substrate.

  As described above, according to the present invention, in the digital variable gain amplifier (digital variable gain amplifier), it is possible to achieve both the followability to the received signal level and the stability.

It is an example of the block diagram of the radio | wireless apparatus 1 which concerns on embodiment of this invention. The block diagram of the front end part 10 which concerns on embodiment of this invention is shown. It is a table | surface which shows the gain variation | change_quantity of the digital variable gain amplifier 100 obtained by the operation | movement by the front end part 92 which concerns on a comparative example. It is a table | surface which shows the amount of gain changes of the digital variable gain amplifier 100 obtained by the operation | movement by the front end part 10 which concerns on an Example. 5 is a graph showing a cumulative value of the amount of change in gain of the digital variable gain amplifier 100 shown in FIGS. 3 and 4 with respect to processing time. The block diagram of the front end part 12 which concerns on the modification 1 of embodiment of this invention is shown. The block diagram of the front end part 90 which concerns on the comparative example 1 is shown. The block diagram of the front end part 92 which concerns on the comparative example 2 is shown.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  An embodiment of the present invention described below is a digital variable gain amplifier (digital variable gain) that is provided in a front end portion of a wireless device that can be used in various wireless communications and that amplifies a received signal while changing the gain. The present invention relates to automatic gain control (AGC (Automatic Gain Control)) for an amplifier.

<< Overview of Wireless Device >>
First, the outline | summary of the radio | wireless apparatus 1 which concerns on embodiment of this invention is demonstrated with reference to FIG. FIG. 1 is an example of a block diagram of a wireless device 1 according to an embodiment of the present invention.

  The wireless device 1 according to the present embodiment can be, for example, a business transceiver base station or portable terminal used in a specific area (for example, in a business office), and more specifically, for example, Bluetooth. (Registered trademark) or ZigBee (registered trademark) for short-range wireless communication (base station or terminal), wireless LAN (Local Area Network), Wi-Fi (registered trademark), or mobile communication network (LTE, 3G), etc., can be a communication interface (base station or terminal). Therefore, in this embodiment, the frequency of the signal received by the wireless device 1 is not particularly limited. For example, the wireless device 1 can receive a signal having a frequency such as a 400 MHz band.

  For example, in the wireless device 1 according to the present embodiment, as illustrated in FIG. 1, a signal received by the antenna of the wireless device 1 is transmitted via a bandpass filter to one or multiple stages of Low Noise Amplifier (LNA) or an attenuator. The data is taken into the front end unit of the wireless device 1 via (ATTenator; ATT) or the like. The captured signal passes through an amplifier (AMPlifer; AMP), is converted into a signal having a low frequency by a frequency conversion circuit (MIXer; MIX), and further passes through a band-pass filter to a variable gain amplifier (AGC). Is input.

  Further, the signal whose signal level is adjusted by the variable gain amplifier is input to a preamplifier (PreAmp) via a bandpass filter, and then input to an A / D (Analog / Digital) converter. Thereafter, the signal from the A / D converter is further processed by various filters, frequency conversion circuits, and the like, and finally input to the demodulation processing unit to be converted as audio information or the like.

  The digital variable gain amplifier according to the embodiment of the present invention described below corresponds to the variable gain amplifier (AGC) of the wireless device 1 described above.

  Note that the wireless device 1 according to the present embodiment is not limited to the wireless device having the configuration shown in FIG. 1, and is a wireless device having another configuration as long as it has a digital variable gain amplifier. There may be.

<< Background to the Embodiment of the Present Invention >>
First, prior to the detailed description of the embodiment of the present invention, the background that the inventor has made the embodiment of the present invention will be described.

  As described above, a variable gain amplifier (variable gain amplifier) that amplifies a received signal while changing the gain is incorporated in the front end portion of the wireless device 1. In such a variable gain amplifier, there are mainly two types of amplifiers, a digital variable gain amplifier and an analog variable gain amplifier.

  The digital variable gain amplifier (digital variable gain amplifier) can adjust the gain discretely by a digital adjustment method. Employing such a digital variable gain amplifier in the front end portion of the wireless device 1 has several advantages. Specifically, the digital variable gain amplifier has a smaller circuit mounting area and a smaller number of components than an analog variable gain amplifier (analog variable gain amplifier), and can be easily integrated into one device. This is advantageous in reducing the size and cost of the wireless device 1. Further, it may be required to adjust the control parameters of the front end unit of the wireless device 1 due to manufacturing variations of components built in the wireless device 1 or changes in the installation environment of the wireless device 1. Then, since it is possible to adjust by software, it is also advantageous that the adjustment can be easily performed as compared with the analog variable gain amplifier.

  However, as described above, since the digital variable gain amplifier has discrete gain adjustment, there is an adjustment unit that is the minimum adjustable width. In an integrated device equipped with the digital variable gain amplifier, Depending on the device process and the like, the adjustment unit tends to increase. Therefore, the digital variable gain amplifier has a larger adjustment unit than the analog variable gain amplifier that can adjust the gain linearly and smoothly. Is difficult to adjust following the fluctuation. Further, in the environment as described above, it is difficult for the digital variable gain amplifier to converge and stabilize the level of the amplified signal, and as a result, the reception performance of the wireless device 1 is degraded. In particular, in an environment where there are many indoors and buildings, radio waves are reflected by walls and the like, so that a desired signal wave to be received by the wireless device 1 is easily affected by interference waves, and the received signal There is a tendency for level fluctuations to become intense.

  Therefore, in view of such a situation, the present inventor has repeatedly studied AGC control capable of achieving both the followability to the received signal level and stability for various variable gain amplifiers. . For example, before the inventor has created an embodiment of the present invention, the following configuration has been studied. Below, examination of the present inventors will be described. In the following description, a configuration that the inventor has studied before creating the embodiment of the present invention is referred to as a comparative example.

  In detail, the comparative example 1 which this inventor examined is the structure disclosed by the said patent document 1. FIG. As shown in FIG. 7 which is a block diagram of the front end unit 90 according to the comparative example 1, the front end unit 90 according to the comparative example 1 includes an analog variable gain amplifier (analog variable gain amplifier) 900 and an A / D. (Analog / Digital) converter 200, demodulation processing unit 410 that demodulates the reception signal converted into a digital signal, reception signal level detection processing unit 422, logarithmic conversion processing unit 424, comparison unit 428, and average processing Unit 450, a D / A (Digital / Analog) converter 202, and an LPF (Low Pass Filter) 902.

  In Comparative Example 1, the received signal input via the analog variable gain amplifier 900 is converted from an analog signal to a digital signal by the A / D converter 200. Further, in the first comparative example, the received signal level detection processing unit 422 that detects the signal level of the digital signal, the logarithmic conversion processing unit 424 that logarithmically converts the detected signal level from the linear value to the logarithmic value, and the logarithmically corrected correction The comparison unit 428 that compares the signal level with the reference signal level C, and the average processing unit 450 that performs average processing (for example, moving average processing) on the comparison result, the signal level of the converted digital signal becomes a predetermined reference value. Thus, a control value for performing feedback control on the analog variable gain amplifier 900 is calculated. In the first comparative example, the calculated control value is converted from a digital signal to an analog signal, passes through the LPF 902 after conversion, and is transmitted to the analog variable gain amplifier 900. Thus, in the comparative example 1, the gain of the analog variable gain amplifier 900 can be linearly varied.

  However, Comparative Example 1 is configured to convert the control value from a digital signal to an analog signal and adjust the analog variable gain amplifier 900 using the LPF 902, and thus is configured based on the analog adjustment method. .

  Accordingly, the present inventor has come up with the idea of adopting a digital variable gain amplifier that is effective in reducing the size and cost of a wireless device, and has considered replacing the configuration of Comparative Example 1 with a digital adjustment method.

  In detail, the front end unit 92 according to the comparative example 2 examined by the present inventor is a block diagram of the front end unit 92 according to the comparative example 1 as shown in FIG. Gain amplifier) 100, A / D converter 200, demodulation processing unit 410, received signal level detection processing unit 422, logarithmic conversion processing unit 424, comparison unit 428, average processing unit 450, and digital variable gain And an amplifier gain adjustment unit 300 that controls the gain (amplification) of the amplifier 100 to be variable. The details of the operation of the front end unit 92 according to the comparative example 2 are the same as those of the comparative example 1 except that the adjustment of the gain of the digital variable gain amplifier is discrete. Description is omitted.

  In the case of Comparative Example 2 in which the configuration as in Comparative Example 1 is simply replaced with a digital adjustment method, in an environment where the fluctuation of the received signal level is severe due to the influence of interference waves, it is difficult to adjust following the fluctuation, The reception performance in the wireless device 1 is deteriorated.

  Specifically, since the configuration of Comparative Example 1 is based on an analog adjustment method, the gain of the analog variable gain amplifier 900 can be adjusted in an arbitrary unit. On the other hand, in the case of the configuration of Comparative Example 2, since the discrete gain is adjusted in units of 1 dB, for example, when the adjustment is to be performed with the intermediate value of 0.5 dB, the gain of the variable gain amplifier. However, it continues to change with the previous and subsequent adjustment values (specifically, values in 1 dB increments) and cannot be converged, and the reception performance of the wireless device 1 deteriorates.

  The above-described degradation in reception performance can be dealt with by increasing the averaging processing time of the average processing unit 450 so that a stable adjustment value can be obtained. Since the followability of the received signal with respect to the signal level deteriorates, it is not possible to cope with a large fluctuation in the signal level of the received signal at the start of reception or when receiving a bursty signal.

  Furthermore, the inventor examined the configurations disclosed in Patent Documents 2 and 3 above. In these Patent Documents 2 and 3, a technique for acquiring a control amount using a limiter processing unit and a delay device and controlling the gain of a variable gain amplifier using the acquired control amount is disclosed. In particular, in Patent Document 2, the control mode in which the followability is improved with respect to the signal level of the input signal and the stability of the control voltage are improved in accordance with the amount of change in the control voltage for controlling the variable gain amplifier. The mode is switched to the controlled mode.

  However, in the configuration disclosed in Patent Document 2 and the like, it takes time to adjust and study the control parameters in order to optimize the control mode switching conditions and the control method, increasing the development time of the wireless device 1 and the wireless device. It is difficult to avoid complication of the structure of 1.

  Therefore, the present inventor has created an embodiment of the invention in view of the above situation. According to the embodiment of the present invention, it is possible to achieve both the followability to the received signal level and the stability in the digital variable gain amplifier. Below, the detail of embodiment of this invention which this inventor created is demonstrated one by one.

<< Embodiment of the Present Invention >>
<Detailed configuration of front end unit 10>
First, a detailed configuration of the front end unit 10 of the wireless device 1 according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram of the front end unit 10 according to the present embodiment.

  The front end unit 10 according to the present embodiment performs analog processing on a received signal input from an antenna (not shown) and the like, converts the received signal subjected to analog processing into a digital signal, a DSP (Digital Signal Processor) or FPGA (FPGA). By performing digital processing (software) using Field-Programmable Gate Array) or the like, it is possible to perform demodulation processing on the received signal or perform feedback control (AGC processing) on the digital variable gain amplifier 100.

  Specifically, as shown in FIG. 2, the front end unit 10 according to this embodiment includes a digital variable gain amplifier (digital variable gain amplifier) 100, an A / D converter (AD conversion unit) 200, and an amplifier gain. An adjustment unit (level control unit) 300 and a digital processing unit 400 are included. Details of each block of the front end unit 10 will be described below.

(Digital variable gain amplifier 100)
The digital variable gain amplifier 100 receives a signal level of a reception signal received via an antenna (not shown), an LNA (Low Noise Amplifier) (not shown), a filter (not shown), and the like from an amplifier gain adjustment unit 300 described later. By adjusting the gain (amplification) in accordance with the control, it can be adjusted. Specifically, the digital variable gain amplifier 100 adjusts the signal level of the received signal to a suitable value by discretely adjusting the gain by a digital adjustment method. The reception signal whose signal level is adjusted by the digital variable gain amplifier 100 is output to an A / D converter 200 described later.

(A / D converter 200)
The A / D converter 200 converts the received signal whose signal level is adjusted from an analog signal to a digital signal. A digital signal, which is a conversion result by the A / D converter 200, is temporarily stored in a register area (not shown) in the A / D converter 200, and an SPI (Serial Peripheral Interface) or I ² C (I Square). It can be read out by an interface such as “Do Sea”. For example, a digital signal temporarily stored in the register area is read out and used for demodulation processing or AGC (Automatic Gain Control) processing in the digital processing unit 400 described later.

(Amplifier Gain Adjustment Unit 300)
The amplifier gain adjustment unit 300 can control the gain (amplification) of the digital variable gain amplifier 100 to be variable, and can adjust the signal level of the received signal. In the present embodiment described below, the gain adjustment unit of the amplifier gain adjustment unit 300 with respect to the digital variable gain amplifier 100 is assumed to be a logarithmic value dB (decibel). However, in the present embodiment, the gain adjustment unit of the amplifier gain adjustment unit 300 with respect to the digital variable gain amplifier 100 is not limited to dB, and may be another adjustment unit. Specifically, the amplifier gain adjustment unit 300 acquires an adjustment amount via an interface such as SPI or I ² C by a digital processing unit 400 described later, and a voltage value corresponding to the acquired adjustment amount is a digital variable gain amplifier. By outputting to 100, the gain of the digital variable gain amplifier 100 can be controlled.

(Digital processing unit 400)
The digital processing unit 400 includes a digital signal processor (DSP), a field-programmable gate array (FPGA), and the like, and performs software processing (digital processing) to perform demodulation processing on the received signal and the digital variable gain amplifier 100. AGC processing can be realized as control for the above. For example, the digital processor 400 temporarily controls the register area (not shown) in the A / D converter 200 via an interface such as SPI or I ² C as a control function for the digital variable gain amplifier 100 or the like. The conversion result (digital signal) stored in is read and output to a demodulation processing unit 410 (to be described later) or an AGC processing unit 420 that performs AGC processing. Specifically, the digital processing unit 400 includes a demodulation processing unit 410 and an AGC processing unit (feedback unit) 420 as shown in FIG. Details of the functional blocks of the digital processing unit 400 will be described below.

-Demodulation processing unit 410-
The demodulation processing unit 410 can demodulate the received signal converted into the digital signal using a method such as π / 4 shift QPSK (Quadrature Phase Shift Keying) or FSK (Frequency Shift Keying).

-AGC processing unit 420-
The AGC processing unit 420 performs software processing (digital processing) using the received signal converted into the digital signal, calculates the gain adjustment amount of the amplifier gain adjusting unit 300 for the digital variable gain amplifier 100 described above, and Feedback control can be performed on the gain adjustment unit 300. Specifically, as shown in FIG. 2, the AGC processing unit 420 includes a received signal level detection processing unit (detection unit) 422, a logarithmic conversion processing unit (logarithmic conversion unit) 424, a correction unit 426, a comparison unit 428, and a change amount calculation. Unit 430, limiter processing unit (control value calculation unit) 440, and subtracter (feedback control unit) 442. Details of the operation of the AGC processing unit 420 will be described later. Hereinafter, details of each functional block of the AGC processing unit 420 will be described.

-Received signal level detection processing unit 422
The reception signal level detection processing unit 422 performs envelope detection on the reception signal converted into the digital signal read from the A / D converter 200 (extracts only the envelope information in the time series of the reception signal). Thus, the signal level of the received signal can be detected. Further, the received signal level detection processing unit 422 outputs the detected signal level to a logarithmic conversion processing unit 424 described later.

-Logarithmic conversion processing unit 424-
The logarithmic conversion processing unit 424 logarithmically converts the signal level detected by the reception signal level detection processing unit 422 described above from a linear value to a logarithmic value (dBm), and outputs the logarithmic conversion result _An to the correction unit 426 described later. be able to.

-Correction unit 426-
Correcting unit 426 can correct the signal level A _n of the received signal logarithmically converted by the logarithmic conversion processing unit 424 described above, to obtain the corrected signal level B _n. Specifically, the correction unit 426, the conversion result A _n logarithmic conversion processing unit 424, processed by the AGC processing unit 420 previously (specifically, were processed before by one processing unit of) the received signal based an adder for adding the feedback control value G _n-1 output from the limiter processing unit 440 to be described later, the correction signal level B _n by adding the feedback control value G _n-1 in the conversion result a _n To get. Further, the correction unit 426 outputs the acquired correction signal level _Bn to the comparison unit 428 described later.

~ Comparator 428 ~
The comparison unit 428 can compare the correction signal level _Bn acquired from the correction unit 426 described above with the reference signal level C, and acquire a comparison result. Specifically, the comparison unit 428 includes a subtracter that subtracts the correction signal level B _n acquired from the correction unit 426 from a preset reference signal level C, and the correction signal level B _n and the reference signal are compared as a comparison result. The difference D _n from level C can be acquired. Further, the comparison unit 428 outputs the acquired difference D _n to a change amount calculation unit 430 (specifically, a delay unit 432 and a subtracter 434 included in the change amount calculation unit 430) and a subtracter 442, which will be described later.

-Change amount calculation unit 430-
The change amount calculation unit 430 and the difference (comparison result) D _n acquired from the comparison unit 428 described above and the AGC processing unit 420 previously processed (specifically, processed by one processing unit before) ) The difference (previous comparison result) D _n-1 (E _n ) related to the received signal is compared, and is the difference between the comparison result D _n and the previous comparison result D _n-1 (E _n ). A change amount _Fn is calculated. Variation F _n calculated by the change amount calculation unit 430 is output to the limiter processing unit 440 to be described later. Specifically, the change amount calculation unit 430 includes a delay unit 432 and a subtracter 434 as shown in FIG. Details of the delay unit 432 and the subtractor 434 included in the change amount calculation unit 430 will be described below.

Delay device 432
The delay unit 432 acquires the difference D _n−1 (E _n ) corresponding to the preceding received signal processed by one processing unit before the difference D _n (E _n ) acquired from the comparison unit 428. Can do. Specifically, the delay unit 432 delays the difference D _n acquired from the comparison unit 428 by one processing unit, and acquires the difference D _n−1 (E _n ) corresponding to the preceding received signal. Further, the delay unit 432 outputs the difference D _n−1 (E _n ) corresponding to the preceding received signal to the subtracter 434.

Subtractor 434
The subtractor 434 changes the amount based on the difference obtained by subtracting the difference D _n−1 (E _n ) corresponding to the preceding reception signal acquired from the delay unit 432 from the difference D _n acquired from the comparison unit 428. _Fn is calculated. Incidentally, the variation F _n calculated corresponds to the variation of the signal level per one processing unit. Further, the subtracter 434 outputs the calculated change amount _{F n} to the limiter processing unit 440 to be described later.

~ Limiter processing unit 440-
Limiter processing unit 440, the amount of change obtained from the subtractor 434 as described above (specifically, the absolute value of the variation) adjustable and F _n, the adjustment unit (digital variable gain amplifier 100 of the digital variable gain amplifier 100 top By calculating the difference from (small width) (control unit) N with 0 as the lower limit and the adjustment unit N as the upper limit, the feedback control value G _n can be obtained. The limiter processing unit 440 outputs the feedback control value G _n obtained based on the received signal that has been processed by the AGC processing unit 420 in advance (specifically, processed by one processing unit before). The control value _Gn is output to the correction unit 426 described above. Furthermore, the limiter processing unit 440 outputs the acquired feedback control value G _n to the subtracter 442 described later.

~ Subtractor 442-
The subtractor 442 calculates a difference between the comparison result D _n acquired from the above-described comparison unit 428 and the feedback control value G _n acquired from the above-described limiter processing unit 440, and based on the calculated difference H _n , the amplifier The gain adjustment unit 300 can be feedback controlled.

Further, the subtractor 442, as calculated above difference H _n is an integer multiple of the digital variable gain (adjustable minimum width digital variable gain amplifier 100) Adjustment units of amplifier 100 (control unit) N, the difference A truncation process for truncating a numerical value equal to or smaller than the adjustment unit N may be performed on H _n , and the amplifier gain adjustment unit 300 may be feedback-controlled based on the difference subjected to the truncation process.

  The digital variable gain amplifier 100, the A / D converter 200, and the amplifier gain adjustment unit 300 described above can be formed on one semiconductor substrate 500, that is, integrated on one integrated device. be able to. Furthermore, both or one of the demodulation processing unit 410 and the AGC processing unit 420 described above may be formed on the semiconductor substrate 500.

<Operation of front end unit 10>
The detailed configuration of the front end unit 10 of the wireless device 1 according to the present embodiment has been described above. Next, details of the operation of the front end unit 10 will be described with reference to FIG.

  First, a received signal that is an analog signal is input to the digital variable gain amplifier 100 via an antenna (not shown), an LNA (not shown), a filter (not shown), or the like. The input received signal is amplified by the digital variable gain amplifier 100 and input to the A / D converter 200.

  The received signal input to the A / D converter 200 is converted from an analog signal to a digital signal by the A / D converter 200. The converted digital signal is temporarily stored in a register area (not shown) in the A / D converter 200 and is read out to the demodulation processing unit 410 and the AGC processing unit 420 in the digital processing unit 400.

  The reception signal converted into the digital signal read from the A / D converter 200 is envelope-detected by the reception signal level detection processing unit 422, whereby the signal level of the reception signal is detected.

The signal level detected by the received signal level detection processing unit 422 is logarithmically converted from a linear value to a logarithmic value (dBm) by the logarithmic conversion processing unit 424, and obtained as a conversion result _An (dBm).

The conversion result A _n (dBm), which is the signal level of the received signal logarithmically converted by the logarithmic conversion processing unit 424, is corrected by the correction unit 426, whereby the correction signal level B _n (dBm) is acquired. In particular, the conversion result to the A _n, treated with AGC processing unit 420 previously (specifically, were processed before by one processing unit of) output from the limiter processing unit 440, which will be described later, based on the received signal The corrected signal level B _n (dBm) is acquired by adding the feedback control value G _n−1 (dB). That is, the correction signal level B _n (dBm) can be calculated by the following formula (1).

Next, the comparison unit 428 compares the correction signal level B _n (dBm) acquired as described above with the reference signal level C (dBm), thereby acquiring the comparison result D _n (dB). Specifically, the comparison unit 428, by subtracting the correction signal level _B n (dBm) from a preset reference signal level C (dBm), the correction signal level _B n (dBm as a comparison result _D n (dB) ) And the reference signal level C (dBm), a comparison result D _n (dB) is acquired. That is, the comparison result D _n (dB) can be calculated by the following mathematical formula (2).

Next, the change amount calculation unit 430 and the difference (comparison result) D _n acquired as described above and the AGC processing unit 420 previously processed (specifically, processing is performed by one processing unit before). The difference (previous comparison result) D _n-1 (E _n ) (dB) relating to the received signal is compared, and the comparison result D _n and the previous comparison result D _n-1 (E _n ) ( A change amount F _n (dB), which is a difference from dB), is calculated.

Specifically, the delay unit 432 having a change amount calculation unit 430, the difference _{E n (= D n-1} corresponding to the preceding received signal that was processed before by one processing unit of than the difference _D n (dB) ) (DB). That is, the comparison result En (dB) can be calculated by the following mathematical formula (3).

Further, the subtractor 434 included in the change amount calculation unit 430 subtracts the difference E _n (dB) corresponding to the preceding reception signal acquired from the delay unit 432 from the difference D _n (dB), thereby changing the amount of change F _n ( dB) is calculated. The calculated change amount F _n (dB) corresponds to the change amount of the signal level per processing unit. That is, the change amount F _n (dB) can be calculated by the following mathematical formula (4).

Next, the amount of change (more specifically, the absolute value of the amount of change) F _n (dB) acquired as described above by the limiter processing unit 440 and the adjustment unit (digital variable gain amplifier 100 of the digital variable gain amplifier 100). The feedback control value G _n (dB) is obtained by calculating the difference from the adjustable minimum width (control unit) N (dB) with 0 as the lower limit and the adjustment unit N as the upper limit. . That is, the feedback control value G _n (dB) can be calculated by the following mathematical formula (5).

Further, the subtractor 442 performs feedback control on the amplifier gain adjustment unit 300 by calculating a difference between the comparison result D _n (dB) acquired as described above and the acquired feedback control value G _n (dB). A difference H _n (dB) is calculated. Specifically, the subtracter 442 can obtain the difference H _n (dB) by subtracting the obtained feedback control value G _n from the comparison result D _n obtained as described above. That is, the difference H _n (dB) can be calculated by the following mathematical formula (6).

The calculated difference H _n (dB) is used when feedback control of the amplifier gain adjustment unit 300 is performed. The amplifier gain adjusting unit 300 controls the gain of the digital variable gain amplifier 100 using the difference H _n (dB).

Further, the difference H _n (dB) is an integral multiple of the adjustment unit (minimum width in which the digital variable gain amplifier 100 can be adjusted) (control unit) N (dB) of the digital variable gain amplifier 100 by the subtractor 442. As described above, a truncation process for truncating a numerical value equal to or less than the adjustment unit N (dB) may be performed. Then, the difference subjected to the truncation process is used when feedback control of the amplifier gain adjustment unit 300 is performed.

The feedback control value G _n obtained as described above _{(dB) is} output to the correction unit 426, the correcting unit 426, the received signal will be processed by the AGC processing unit 420 after only 1 treatment unit of It is added to the conversion result A _{n + 1} (dBm), and the correction signal level B _{n + 1} (dBm) related to the received signal after one processing unit is calculated. That is, the correction signal level B _{n + 1} (dBm) can be calculated by the following mathematical formula (7). Since the subsequent operation is the same as the above-described operation, the description thereof is omitted here.

The AGC processing unit 420 repeats a series of operations as described above until the difference between the correction signal level B _n (dBm) and the reference signal level C (dBm) disappears, and the gain of the digital variable gain amplifier 100 is adjusted. It will be.

  As described above, according to the present embodiment, since the adjustment amount is suppressed when adjusting the gain of the digital variable gain amplifier 100, the signal level of the reception signal input to the demodulation processing unit 410 is stabilized. Therefore, the reception performance of the wireless device 1 can be improved. That is, according to the present embodiment, even in an environment where the signal level of the received signal varies greatly due to the influence of the interference wave, the digital variable gain amplifier 100 can follow the varying received signal level well and vary the gain. The signal level of the received signal input to the demodulation processing unit 410 can be stabilized.

  Furthermore, according to the present embodiment, the parameter for adjusting the gain of the digital variable gain amplifier 100 obtained by the AGC processing unit 420 conforms to the adjustment unit N of the digital variable gain amplifier 100. No complicated adjustments or examinations are required, and an increase in time related to the development time of the wireless device 1 can be suppressed.

<< Example >>
The details of the operation of the front end unit 10 according to the present embodiment have been described above. Next, an example of the operation according to the present embodiment will be described more specifically with reference to specific examples. In addition, the Example shown below is an example of the operation | movement which concerns on this embodiment to the last, Comprising: The operation | movement which concerns on this embodiment is not limited to the following example.

  In order to more specifically describe an example of the operation according to the present embodiment, the movement of the gain change amount of the digital variable gain amplifier 100 obtained by the operation (example) by the front end unit 10 according to the present embodiment, 8 is compared with the movement of the gain change amount of the digital variable gain amplifier 100 obtained by the operation of the front end unit 92 according to the comparative example shown in FIG. FIG. 3 is a table showing the gain change amount of the digital variable gain amplifier 100 obtained by the operation of the front end unit 92 according to the comparative example. Furthermore, FIG. 4 is a table showing the amount of gain change of the digital variable gain amplifier 100 obtained by the operation of the front end unit 10 according to the embodiment.

  Specifically, FIG. 3 shows the signal level of the input received signal, the gain of the digital variable gain amplifier 100, and the logarithmically converted reception for each unit processing time obtained from the AGC control operation by the front end unit 92 according to the comparative example. A comparison result D that is a difference between the signal level A of the signal and the reference signal level C, a gain of the digital variable gain amplifier 100 set in the next unit processing time, and a change in gain of the digital variable gain amplifier 100 are shown. . 4 shows the signal level of the received signal, the gain of the digital variable gain amplifier 100, and the logarithmically converted received signal for each unit processing time obtained from the AGC control operation by the front end unit 10 according to the present embodiment. Signal level A, corrected received signal level (corrected signal level) B, comparison result D that is a difference from reference signal level C, variation F, calculated value of limiter processing unit 440 (| F | −N), The movement of the feedback G, the difference H, the gain of the digital variable gain amplifier 100 set in the next unit processing time, and the gain change amount of the digital variable gain amplifier 100 is shown.

  More specifically, the results of FIGS. 3 and 4 can be obtained under the following conditions. First, the front end units 10 and 92 start reception of a desired reception signal having a signal level of −20.25 dBm at a processing time of 0, and after the processing time of 10, an interference wave is generated in addition to the desired reception signal. To receive. That is, after the processing time 10, the signal level of the received signal varies within a range of −19.75 dBm to −20.25 dBm. The reference signal level C is set to 10 dBm, the adjustment unit N of the digital variable gain amplifier 100 is set to 1 dB, and one unit of processing time is set to 100 μsec. Furthermore, it is assumed that the average processing unit 450 is not built in the front end units 10 and 92.

  As can be seen from FIGS. 3 and 4, in both the comparative example and the embodiment, after the processing time 10, since the interference wave is received in addition to the desired reception signal, the signal level of the reception signal varies. It has become intense.

  As shown in FIG. 3, in the comparative example, the signal level of the received signal is greatly fluctuated by the interference wave after the processing time 10, so that the gain of the set digital variable gain amplifier 100 is not stable, The amount of change in gain of the digital variable gain amplifier 100 will also constantly change.

  On the other hand, as shown in FIG. 4, in the embodiment, even when the signal level of the received signal fluctuates significantly due to the interference wave after the processing time 10, the gain of the set digital variable gain amplifier 100 is The amount of change in the gain of the digital variable gain amplifier 100 is stable and suppressed to a small value.

  Next, the difference between the comparative example and the example will be described with reference to FIG. FIG. 5 is a graph showing the cumulative value of the amount of change in gain of the digital variable gain amplifier 100 shown in FIGS. 3 and 4 with respect to the processing time.

  As can be seen from FIG. 5, in the processing time 20, the cumulative value of the magnitude of the gain change of the digital variable gain amplifier 100 of the embodiment is the magnitude of the magnitude of the gain change of the digital variable gain amplifier 100 of the comparative example. Is about half of the cumulative value of. Further, according to FIG. 5, the accumulated value of the magnitude of the gain change amount of the digital variable gain amplifier 100 of the example is suppressed to about ３ of the comparative example in the processing time 10 to 20. Recognize. That is, it can be seen that the signal level of the reception signal input to the demodulation processing unit 410 is stable in the embodiment and the reception performance of the wireless device 1 can be improved as compared with the comparative example.

  As described above, according to the present embodiment, since the adjustment amount is suppressed when adjusting the gain of the digital variable gain amplifier 100, the signal level of the reception signal input to the demodulation processing unit 410 is stabilized. Therefore, the reception performance of the wireless device 1 can be improved. That is, according to the present embodiment, even in an environment where the signal level of the received signal varies greatly due to the influence of the interference wave, the digital variable gain amplifier 100 can follow the varying received signal level well and vary the gain. The signal level of the received signal input to the demodulation processing unit 410 can be stabilized.

  Furthermore, according to the present embodiment, the parameter for adjusting the gain of the digital variable gain amplifier 100 obtained by the AGC processing unit 420 conforms to the adjustment unit N of the digital variable gain amplifier 100. No complicated adjustments or examinations are required, and an increase in time related to the development time of the wireless device 1 can be suppressed.

<< Modification >>
In the present embodiment, the configuration of the front end unit 10 is not limited to the configuration illustrated in FIG. 2 and can be variously modified. Below, the modification of the front end part 10 which concerns on this embodiment is demonstrated with reference to FIG. FIG. 6 is a block diagram of the front end unit 12 according to the first modification of the present embodiment.

(Modification 1)
In the first modification of the present embodiment, as shown in FIG. 6, the front end unit 12 includes an average processing unit 450 that averages the comparison result D _n from the comparison unit 428 and outputs the average result to the change amount calculation unit 430. You may have. The averaging processing unit 450 takes time for the averaging process by averaging the comparison result D _n that fluctuates in an environment where the signal level of the received signal varies greatly due to the influence of the interference wave. The signal level of the reception signal input to the processing unit 410 can be further stabilized.

(Modification 2)
In the above-described embodiment, the digital variable gain amplifier 100, the A / D converter 200, and the amplifier gain adjustment unit 300 are described as being formed on one semiconductor substrate 500. However, in the present embodiment, the present invention is not limited to this, and the digital variable gain amplifier 100, the A / D converter 200, and the amplifier gain adjustment unit 300 are integrated on one semiconductor substrate 500. Instead, the wireless device 1 may be mounted as a separate component.

<< Supplementary >>
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Radio | wireless apparatus 10, 12, 90, 92 Front end part 100 Digital variable gain amplifier 200 A / D converter 202 D / A converter 300 Amplifier gain adjustment part 400 Digital processing part 410 Demodulation processing part 420 AGC processing part 422 Received signal Level detection processing unit 424 Logarithmic conversion processing unit 426 Correction unit 428 Comparison unit 430 Change amount calculation unit 432 Delay unit 434, 442 Subtractor 440 Limiter processing unit 450 Average processing unit 500 Semiconductor substrate 900 Analog variable gain amplifier 902 LPF

Claims (9)

A variable gain amplifier that variably amplifies the received signal;
An AD converter that converts the received signal output from the variable gain amplifier from an analog signal to a digital signal;
A level control unit for controlling the signal level of the converted received signal;
A feedback unit that performs feedback control on the level control unit;
With
The feedback unit includes:
A detection unit for detecting a signal level of the converted digital signal;
A logarithmic conversion unit for logarithmically converting the detected signal level;
A correction unit that corrects the logarithmically converted signal level by adding a feedback control value corresponding to the previously received previous received signal to the conversion result of the logarithmic conversion, and acquires a correction signal level;
A comparison unit that compares the correction signal level with a reference signal level and obtains a comparison result;
A change amount calculation unit that calculates a change amount from a difference between the comparison result and the comparison result corresponding to the preceding received signal processed in advance;
A difference between the change amount and the control unit of the variable gain amplifier is calculated with the control unit as an upper limit, and a control value calculation unit for obtaining the feedback control value;
A feedback control unit that feedback-controls the level control unit based on a difference between the comparison result and the feedback control value;
Having
Wireless device. The change amount calculation unit
A delay unit for obtaining the comparison result corresponding to the preceding reception signal processed one processing unit ahead of the reception signal;
A subtractor that calculates the amount of change from the difference between the comparison result and the comparison result corresponding to the preceding received signal;
Having
The wireless device according to claim 1.   The radio apparatus according to claim 1, wherein the control value calculation unit obtains the feedback control value by subtracting a control unit of the variable gain amplifier from an absolute value of the change amount. The feedback control unit is a numerical value equal to or less than the control unit with respect to the difference between the comparison result and the feedback control value so that the difference between the comparison result and the feedback control value is an integral multiple of the control unit. Performing a truncation process, and feedback-controlling the variable gain amplifier based on the difference subjected to the truncation process.
The radio | wireless apparatus of any one of Claims 1-3.   The said feedback part further has an average process part which carries out the average process of the said comparison result from the said comparison part, and outputs it to the said variation | change_quantity calculation part and the said feedback control part. Wireless devices.   The radio apparatus according to claim 1, wherein the variable gain amplifier includes a digital variable gain amplifier that adjusts a gain discretely.   The radio apparatus according to claim 1, further comprising a demodulation processing unit that demodulates the converted digital signal.   The radio apparatus according to claim 1, wherein the variable gain amplifier, the AD conversion unit, and the level control unit are formed on one semiconductor substrate.   The wireless device according to claim 8, wherein the feedback unit is formed on the semiconductor substrate.

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