JP4093230B2 - Receiving device, receiving method, and integrated circuit for receiving device - Google Patents

Description

  The present invention relates to a receiving device, a receiving method, and an integrated circuit for the receiving device.

In recent years, research on mobile communication receivers for mobile communication terminals such as mobile phones and in-vehicle televisions to receive digital signals has been actively conducted. As such a digital signal receiver, in order to maintain good reception quality, the received signal is detected, noise included in the detected signal is detected and compared with a predetermined value, and AGC (Auto Patent Document 1 discloses a technique for performing gain control.
JP-A-8-330985

  However, in the case of the technique disclosed in Patent Document 1, it is difficult to perform optimal AGC control because AGC control is performed by detecting noise of a signal before being demodulated. In the case of a mobile communication receiver, the reception status changes due to movement, and the voltage level of the received signal can change abruptly. In such a case, the technique of Patent Document 1 cannot properly perform AGC control, which causes a deterioration in reception quality.

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide a receiving apparatus, a receiving method, and an integrated circuit for the receiving apparatus that perform appropriate AGC control so as to maintain optimum reception quality. .

In order to solve the above-described problems, a receiving apparatus according to a first aspect of the present invention includes first amplifying means (for example, RF-AGC22 in FIG. 1) for amplifying a received signal received by an antenna, A second amplifying means (for example, IF-AGC 26 in FIG. 1) that extracts and amplifies a signal in the frequency band of the target selected station from the received signal amplified by the one amplifying means; and the second amplifying means. Demodulating means for demodulating the amplified signal of the selected station (for example, demodulating circuit unit 3 in FIG. 1) and received signal strength detecting means for detecting the signal strength of the received signal received by the antenna (for example, in FIG. 1) RSSI output circuit 4), amplified signal strength detection means (for example, signal strength detection circuit 351 in FIG. 2) for detecting the signal strength of the signal of the selected station amplified by the second amplification means, and the amplified signal strength detection Detected by first comparison means (for example, first comparison circuit 352 in FIG. 2) for comparing the signal strength of the signal of the selected station detected by the stage with a first predetermined value, and the received signal strength detection means Second comparison means (for example, the second comparison circuit 354 in FIG. 2) for comparing the received signal strength with a second predetermined value, the comparison result of the first comparison means and the second comparison value . AGC voltage control means for controlling the amplification factor in the first amplification means and the amplification factor in the second amplification means based on the comparison result of the comparison means (for example, the AGC voltage control circuit 35 in FIG. 1). And.

According to a second aspect of the invention, a receiving apparatus according to claim 1, wherein the AGC voltage control means, the signal strength before Symbol first signal of a result of comparison the selected station by comparing means of said second If the signal intensity of the received signal is smaller than a predetermined value of 1 and the signal intensity of the received signal is larger than the second predetermined value as a result of comparison by the second comparing means, the amplification factor in the first amplifying means is decreased, Control for increasing the amplification factor in the second amplification means is performed.

According to a third aspect of the invention, a receiving apparatus according to claim 1, wherein the AGC voltage control means, the signal strength before Symbol first signal of a result of comparison the selected station by comparing means of said second The signal strength of the received signal is smaller than the second predetermined value as a result of the comparison by the second comparing means, and the increase of the amplification factor in the first amplifying means is small. When possible, control is performed to maintain the amplification factor in the first amplification unit and increase the amplification factor in the second amplification unit.

The invention of claim 4 is a reception apparatus according to claim 1, wherein the AGC voltage control means, the signal strength before Symbol first signal of a result of comparison the selected station by comparing means of said second The signal strength of the received signal is smaller than the second predetermined value as a result of the comparison by the second comparing means, and the amplification factor in the first amplifying means can be increased. In this case, control is performed to increase the amplification factor in the first amplification unit and maintain the amplification factor in the second amplification unit.

The invention according to claim 5, A receiver as claimed in claim 1, wherein the AGC voltage control means, the signal strength before Symbol first signal of a result of comparison the selected station by comparing means of said second The first amplifying means and the second amplifying means when the signal intensity of the received signal is greater than the second predetermined value as a result of comparison by the second comparing means. Control is performed to reduce the amplification factor.

The invention of claim 6 is a reception apparatus according to claim 1, wherein the AGC voltage control means, the signal strength before Symbol first signal of a result of comparison the selected station by comparing means of said second The signal intensity of the received signal is smaller than the second predetermined value as a result of comparison by the second comparing means, and the amplification factor in the second amplifying means does not decrease. When possible, control is performed to reduce the amplification factor in the first amplification unit and maintain the amplification factor in the second amplification unit.

The invention of claim 7 is a receiving apparatus according to claim 1, wherein the AGC voltage control means, the signal strength before Symbol first signal of a result of comparison the selected station by comparing means of said second The signal intensity of the received signal is smaller than the second predetermined value as a result of comparison by the second comparing means, and the amplification factor in the second amplifying means can be reduced. In such a case, control is performed to maintain the gain in the first amplifying means and decrease the gain in the second amplifying means.

  The invention according to claim 8 is the receiving apparatus according to any one of claims 2 to 7, wherein the second predetermined value is variable in accordance with an amplification factor in the first amplification means. It is characterized by.

According to a ninth aspect of the present invention, there is provided a reception method of a first amplification step (for example, RF-AGC22 in FIG. 1) for amplifying a reception signal received by an antenna, and reception amplified by the first amplification step. A second amplification step (for example, IF-AGC 26 in FIG. 1) that extracts and amplifies the signal in the frequency band of the target selection station from the signal, and demodulates the signal of the selection station amplified by the second amplification step. demodulation step of (e.g., demodulation circuit 3 of FIG. 1), a received signal strength detection step of detecting a signal strength of the reception signal received by the antenna (e.g., RSSI output circuit 4 in FIG. 1), the first amplifying the signal intensity detecting step of detecting a signal strength of the amplified selected station signal by a second amplification step (e.g., signal strength detection circuit 351 in FIG. 2) and the selection detected by the amplified signal strength detecting step A first comparison step (for example, the first comparison circuit 352 in FIG. 2) for comparing the signal strength of the station signal with a first predetermined value, and the signal of the reception signal detected by the reception signal strength detection step A second comparison step (for example, the second comparison circuit 354 in FIG. 2) that compares the intensity with a second predetermined value, a comparison result of the first comparison step, and a comparison result of the second comparison step And an AGC voltage control step (for example, the AGC voltage control circuit 35 in FIG. 1) for controlling the amplification factor in the first amplification step and the amplification factor in the second amplification step. And

The integrated circuit for a receiver according to claim 10 includes a first amplifier circuit (for example, RF-AGC22 in FIG. 1) for amplifying a reception signal received by a connected antenna, and the first amplifier circuit. A second amplifier circuit (for example, IF-AGC 26 in FIG. 1) for extracting and amplifying a signal in the frequency band of the target selected station from the amplified received signal, and the selected station amplified by the second amplifier circuit And a received signal strength detection circuit for detecting the signal strength of the received signal received by the antenna (for example, the RSSI output circuit 4 in FIG. 1). When an amplifying signal strength detection circuit for detecting the signal strength of the second amplified selected station signal by the amplifier circuit (e.g., signal strength detection circuit 351 in FIG. 2), by the amplified signal strength detection circuit A first comparison circuit (for example, the first comparison circuit 352 in FIG. 2) that compares the signal strength of the signal of the selected station that has been output and a first predetermined value, and the reception signal strength detection circuit A second comparison circuit (for example, the second comparison circuit 354 in FIG. 2) that compares the signal strength of the received signal with a second predetermined value, the comparison result of the first comparison circuit, and the second comparison An AGC voltage control circuit (for example, the AGC voltage control circuit 35 in FIG. 1) that controls the amplification factor in the first amplification circuit and the amplification factor in the second amplification circuit based on the comparison result of the circuits ; It is characterized by providing.

  According to the first aspect of the present invention, even when the reception apparatus is moved and the reception situation of the radio wave is changed, the amplification factors of the first amplification unit and the second amplification unit are automatically set to appropriate amplification factors. Can be controlled. For this reason, optimal reception quality can be ensured and the reception performance of the reception apparatus can be improved. The inventions according to claims 9 and 10 also have the same effect.

  According to the second to seventh aspects of the present invention, based on the comparison result between the signal strength of the signal of the selected station and the first predetermined value, and the comparison result between the reception strength of the reception signal and the second predetermined value. By controlling the increase / decrease in the amplification factor of the first amplification means and the second amplification means, it is possible to control the increase / decrease in the amplification factor in consideration of the margin to the linearity degradation of the first amplification means. It becomes. Accordingly, for example, even when the reception apparatus is moved and the reception state of the radio wave is changed, the first amplifying unit always operates within a range in which the linearity is maintained. The amplification factors of the amplification unit and the second amplification unit can be automatically controlled to an appropriate amplification factor. As a result, even when the received signal changes from moment to moment, the optimum reception quality can always be ensured, and the reception performance of the receiving apparatus can be improved.

  According to the invention described in claim 8, the second predetermined value can be set according to the amplification factor of the first amplification means. Thereby, based on the amplification factor of the first amplification means, it is possible to perform increase / decrease control of the amplification factor so as to effectively utilize the range in which the linearity of the first amplification means is maintained. Accordingly, for example, even when the reception apparatus is moved and the reception state of the radio wave is changed, the first amplifying unit always operates within a range in which the linearity is maintained. The amplification factors of the amplification unit and the second amplification unit can be automatically controlled to an appropriate amplification factor. As a result, even when the received signal changes from moment to moment, the optimum reception quality can always be ensured, and the reception performance of the receiving apparatus can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment described below, a case where the receiving apparatus of the present invention is applied to a receiving apparatus for mobile communication for receiving radio waves of digital broadcasting will be described.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration of a receiving apparatus 100 that receives radio waves of digital broadcasting. The receiving apparatus 100 includes an antenna 1, a tuner circuit 2, a demodulation circuit unit 3, and an RSSI output circuit 4. Here, each component of the receiving apparatus 100 may be configured by a semiconductor integrated circuit except for the antenna 1.

  The tuner circuit 2 includes an LNA (Low Noise Amplifier) 21, an RF-AGC 22, a BPF (Band Pass Filter) 23 and 25, an RF mixer 24, an IF-AGC 26, an IF mixer 27, and an LPF (Low Pass Filter). 28).

  The radio wave received by the antenna 1 is first amplified by the LNA 21 and the RF-AGC 22 with a predetermined amplification factor. Here, the amplification factor of the RF-AGC 22 is controlled by a signal RFS output from an AGC voltage control circuit 35 to be described later so as to have an appropriate value.

  The signal S3 output from the RF-AGC 22 is cut out only in a frequency band having a predetermined width by the BPF 23, and further converted into an intermediate frequency signal having a predetermined center frequency by the RF mixer 24. The signal output from the RF mixer 24 is cut out only in a predetermined frequency band by the BPF 25 and amplified by the IF-AGC 26.

  The signal output from the IF-AGC 26 is converted into a broadcast wave signal having a predetermined center frequency by passing through the IF mixer 27 and the LPF 28. Here, the amplification factor of the IF-AGC 26 is controlled by a signal IFS output from an AGC voltage control circuit 35 described later so as to have an appropriate value.

  Further, the signal S3 output from the RF-AGC 22 is input to the RSSI output circuit 4, an RSSI (Received Signai Strength Indicator) value is detected as the intensity value of the received signal, and a signal RS indicating the detected RSSI value is output. The Here, the RSSI output circuit 4 is a circuit that detects and outputs the intensity of the received signal.

  The demodulation circuit unit 3 includes an ADC (Analog to Digital Converter) 31, an FFT (Fast Fourier Transform) 32, a waveform equivalent circuit 33, an error correction circuit 34, and an AGC voltage control circuit 35.

  The signal S2 output from the tuner circuit 2 is A / D converted by the ADC 31 and subjected to Fourier transform processing by the FFT 32. The signal output from the FFT 32 is subjected to waveform equivalent processing (amplitude equivalent and phase equivalent) by the waveform equivalent circuit 33, and further subjected to error correction processing by the error correction circuit 34. And it outputs to the exterior of the receiver 100 as TS (Transport Stream).

  The AGC voltage control circuit 35 compares the signal MS output from the ADC 31 with the first predetermined value, the signal RS output from the RSSI output circuit 4 and the second predetermined value, and determines the RFAGC voltage according to each comparison result. It is a circuit that determines the increase or decrease of the IFAGC voltage. Here, the RFAGC voltage is a voltage for controlling the amplification factor of the RF-AGC 22, and the IFAGC voltage is a voltage for controlling the amplification factor of the IF-AGC26.

  FIG. 2 is a block diagram showing a configuration of the AGC voltage control circuit 35. The AGC voltage control circuit 35 includes a signal strength detection circuit 351, a first comparison circuit 352, an ADC 353, a second comparison circuit 354, a gain distribution control circuit 355, an IF-AGC arithmetic circuit 356, and a DAC (Digital to Digital). Analog Converter) 357 and 359, and an RF-AGC arithmetic circuit 358.

  The signal intensity output from the ADC 31 is detected by the signal intensity detection circuit 351 from the amplitude of the signal. That is, the signal strength detection circuit 351 detects the signal strength of the signal S2 output from the tuner circuit 2. Then, the detected signal intensity is compared with a first predetermined value by the first comparison circuit 352. The signal RS output from the RSSI output circuit 4 is A / D converted by the ADC 353 and compared with a second predetermined value by the second comparison circuit 354.

  The gain distribution control circuit 355 determines increase / decrease in the RFAGC voltage and the IFAGC voltage based on the comparison results output from the first comparison circuit 352 and the second comparison circuit 354. IF-AGC arithmetic circuit 356 calculates the IFAGC voltage according to the increase / decrease of the IFAGC voltage determined by gain distribution control circuit 355. The calculated IFAGC voltage is D / A converted by the DAC 357 and output to the IF-AGC 26 as a signal IFS. The RF-AGC arithmetic circuit 358 calculates the RFAGC voltage according to the increase / decrease of the RFAGC voltage determined by the gain distribution control circuit 355. The calculated RFAGC voltage is D / A converted by the DAC 359 and output to the RF-AGC 22 as a signal RFS.

  Next, the RSSI value characteristic indicated by the signal RS with respect to the signal level of the signal S1 input to the RF-AGC 22 and the signal level characteristic of the output signal S2 of the tuner circuit 2 with respect to the signal level of the signal S1 will be described. FIG. 3 is a graph showing an example of the relationship between the signal level of the signal S1 and the RSSI value indicated by the signal RS for each control voltage of the RF-AGC22. FIG. 4 is a graph showing an example of the relationship between the signal level of the signal S1 and the signal level of the signal S2 for each AGC control voltage of the RF-AGC 22 when the amplification degree of the IF-AGC 26 is held at a constant value. In this case, since the relationship between the signal level of the signal S1 and the signal level of the signal S2 is apparently equal to the relationship between the signal level of the signal S1 and the signal level of the signal S3, the input / output characteristics of the RF-AGC 22 are estimated from FIG. can do.

In FIG. 4, for example, when the RFAGC voltage = e, the linearity of the signal level of the signal S2 deteriorates when the input level of the signal S1 becomes −40 [dBm] or more. Here, since the amplification degree of the IF-AGC 26 is held at a constant value, the linearity of the signal S2 is deteriorated, so that it is estimated that the linearity of the signal S3 input to the RSSI output circuit 4 is deteriorated. The Therefore, when the RFAGC voltage = e in FIG. 4, the linearity of the signal S3 input to the RSSI output circuit 4 is maintained until the input level of the signal S1 is −40 [dBm], and becomes greater than −40 [dBm]. It can be seen that the linearity of the signal S3 input to the RSSI output circuit 4 deteriorates.
In FIG. 3, when the RFAGC voltage = e, the RSSI value of the signal RS when the input level of the signal S1 is −40 [dBm] is 2600 [mV], and when it exceeds 2600 [mV], the RF-AGC22 It can be seen that the linearity of the signal output from is deteriorated. This is because the linearity of the signal 3 input to the RSSI output circuit 4 deteriorates when the input level of the signal S1 becomes −40 [dBm] or more, and the linearity of the signal RS that is the output of the RSSI output circuit 4 is reduced. It is thought to deteriorate.

  In this way, by observing the RSSI value of the signal RS, it is possible to know the range in which the signal S3 input to the RSSI output circuit 4 maintains linearity and the margin until the linearity deteriorates. From the above, the second predetermined value used for comparison in the second comparison circuit 354 is set to a level that maintains the linearity of the RF-AGC 22, and the increase / decrease in the amplification factor of the RF-AGC 22 is determined according to the RSSI value of the signal RS. By doing so, it is possible to perform amplification with a good S / N ratio while maintaining undistorted amplification with respect to the RF-AGC 22. For example, for each amplification factor of the RF-AGC 22, the second predetermined value is set to a value obtained by obtaining an upper limit value for maintaining the linearity of the RSSI value of the signal RS. The first predetermined value is also set to an appropriate value determined by design or experiment.

  Next, the AGC voltage control of this embodiment will be described in more detail. FIG. 5 is a flowchart for explaining the flow of the circuit operation of the AGC voltage control circuit 35. First, the gain distribution control circuit 355 outputs an instruction signal so as to set the RFAGC voltage and the IFAGC voltage to minimum values (step A1). Based on this instruction signal, the IF-AGC arithmetic circuit 356 calculates an IFAGC voltage, and the calculation result is D / A converted by the DAC 357 and output to the IF-AGC 26 as a signal IFS. Further, an RFAGC voltage is calculated by the RF-AGC arithmetic circuit 358, and the calculation result is D / A converted by the DAC 359 and output as a signal RFS to the RF-AGC 22.

  Next, the broadcast channel is set, and the reception signal of the selected station is received by the antenna 1 (step A2). The received signal is subjected to processing such as amplification and conversion to an intermediate frequency signal by the tuner circuit 2, and a broadcast wave signal is input to the ADC 31. The signal strength detection circuit 351 receives the signal MS output from the ADC 31, and compares the signal strength of the signal MS with a first predetermined value (step A3). When the signal intensity of the signal MS is the same as the first predetermined value (Step A3; No, Step A4; No), the RFAGC voltage and the IFAGC voltage are not increased or decreased. On the other hand, when the signal strength of the signal MS is larger than the first predetermined value (step A3; No, step A4; Yes), the second comparison circuit 354 compares the RSSI value indicated by the signal RS with the second predetermined value (step A5). ). When the RSSI value is equal to or smaller than the second predetermined value (step A5; No), the gain distribution control circuit 355 determines whether or not the IFAGC voltage can be decreased. If it is possible (step A7; Yes), the RFAGC. The voltage is fixed and the IFAGC voltage is decreased (step A9). If the IFAGC voltage cannot be decreased (step A7; No), the gain distribution control circuit 355 decreases the RFAGC voltage and fixes the IFAGC voltage (step A8).

  Returning to step A5, when the RSSI value is larger than the second predetermined value (step A5; Yes), the gain distribution control circuit 355 decreases the RFAGC voltage and the IFAGC voltage (step A6).

  Returning to step A3, when the signal strength of the signal MS is smaller than the first predetermined value (step A3; Yes), the gain distribution control circuit 355 compares the RSSI value with the second predetermined value, and the RSSI value is equal to or less than the second predetermined value. In the case (step A10; No), it is determined whether or not the RFAGC voltage can be increased. If it is possible (step A12; Yes), the gain distribution control circuit 355 increases the RFAGC voltage and fixes the IFAGC voltage (step A13). When it is impossible (step A12; No), the gain distribution control circuit 355 fixes the RFAGC voltage and increases the IFAGC voltage (step A14).

  Returning to step A10, when the RSSI value is larger than the second predetermined value (step A10; Yes), the gain distribution control circuit 244 decreases the RFAGC voltage and increases the IFAGC voltage (step A11).

By repeating the above operation, the amplification factors of the RF-AGC 22 and the IF-AGC 26 can be appropriately controlled even when the reception apparatus 100 is moved and the reception state of the radio wave changes. For this reason, the reception quality of the received signal can be maintained at an optimum value, and the reception performance of the receiving apparatus 100 can be improved.
According to the first embodiment, the first result is based on the comparison result between the signal strength of the signal of the selected station and the first predetermined value, and the comparison result between the reception strength of the received signal and the second predetermined value. By controlling the increase / decrease in the amplification factor of the second amplification unit and the second amplification unit, it is possible to control the increase / decrease in the amplification factor in consideration of the margin to the linearity degradation of the first amplification unit. Accordingly, for example, even when the reception apparatus is moved and the reception state of the radio wave is changed, the first amplifying unit always operates within a range in which the linearity is maintained. The amplification factors of the amplification unit and the second amplification unit can be automatically controlled to an appropriate amplification factor. As a result, even when the received signal changes from moment to moment, the optimum reception quality can always be ensured, and the reception performance of the receiving apparatus can be improved.

[Second Embodiment]
In the first embodiment, the RSSI value indicated by the signal RS is compared with the second predetermined value in the second comparison circuit, and the RFAGC voltage and the IFAGC voltage are compared based on the comparison results of the first comparison circuit and the second comparison circuit. The case where the increase / decrease is determined has been described. However, according to the RSSI characteristics of the signal RS with respect to the signal level of the signal S1 shown in FIG. 3, the upper limit value at which the linearity of the signal RS is maintained varies depending on each RFAGC voltage. The second embodiment is an embodiment for solving this problem, and the threshold used for comparison in the second comparison circuit is changed according to the RFAGC voltage. The configuration of the receiving device in the second embodiment is such that the AGC voltage control circuit 35 of the receiving device 100 described in the first embodiment is an AGC voltage control circuit 35a shown in FIG. Therefore, the description of the same components is omitted, and only the AGC voltage control circuit 35a is described. Further, the AGC voltage control circuit 35a shown in FIG. 6 may be configured by a semiconductor integrated circuit.

  FIG. 6 is a block diagram showing a configuration of the AGC voltage control circuit 35a. The AGC voltage control circuit 35a includes a signal strength detection circuit 351, a first comparison circuit 352, an ADC 353, a second comparison circuit 354, a gain distribution control circuit 355, an IF-AGC arithmetic circuit 356, DACs 357 and 359, , An RF-AGC arithmetic circuit 358 and a threshold value holding circuit 360 are provided.

As shown in FIG. 7, the threshold value holding circuit 360 stores a threshold value used for comparison by the second comparison circuit 354 in association with the RFAGC voltage. The threshold is set for each RFAGC voltage based on the upper limit value of the RSSI value at which the linearity of the RF-AGC 22 is maintained. The threshold holding circuit 360 detects the RFAGC voltage set by the RF-AGC arithmetic circuit 358 and outputs the corresponding threshold to the second comparison circuit 354. For example, when the RFAGC arithmetic circuit 358 sets “RFAGC voltage = e”, the threshold holding circuit 360 outputs “2300 [mV]” as the threshold to the second comparison circuit 354.

  The signal intensity output from the ADC 31 is detected by the signal intensity detection circuit 351 based on the amplitude of the signal, and the detected signal intensity is compared with a first predetermined value by the first comparison circuit 352. The signal RS output from the RSSI output circuit 4 is A / D converted by the ADC 353 and compared with the threshold value output from the threshold holding circuit 360 by the second comparison circuit 354.

  The gain distribution control circuit 355 determines increase / decrease in the RFAGC voltage and the IFAGC voltage based on the comparison results output from the first comparison circuit 352 and the second comparison circuit 354. IF-AGC arithmetic circuit 356 calculates the IFAGC voltage according to the increase / decrease of the IFAGC voltage determined by gain distribution control circuit 355. The calculated IFAGC voltage is D / A converted by the DAC 357 and output to the IF-AGC 26 as a signal IFS. The RF-AGC arithmetic circuit 358 calculates the RFAGC voltage according to the increase / decrease of the RFAGC voltage determined by the gain distribution control circuit 355. The calculated RFAGC voltage is D / A converted by the DAC 359 and output to the RF-AGC 22 as a signal RFS.

  FIG. 8 is a flowchart for explaining the circuit operation flow of the AGC voltage control circuit 35a. First, the gain distribution control circuit 355 outputs an instruction signal so that the RFAGC voltage and the IFAGC voltage are set to the minimum values (step B1). Based on this instruction signal, the IF-AGC arithmetic circuit 356 calculates an IFAGC voltage, and the calculation result is D / A converted by the DAC 357 and output to the IF-AGC 26 as a signal IFS. Further, an RFAGC voltage is calculated by the RF-AGC arithmetic circuit 358, and the calculation result is D / A converted by the DAC 359 and output as a signal RFS to the RF-AGC 22.

  Next, the broadcast channel is set, and the reception signal of the selected station is received by the antenna 1 (step B2). The received signal is subjected to processing such as amplification and conversion to an intermediate frequency signal by the tuner circuit 2, and a broadcast wave signal is input to the ADC 31. The threshold holding circuit 360 detects the RFAGC voltage from the RF-AGC arithmetic circuit 358 (step B3), and outputs a threshold corresponding to the detected RFAGC voltage to the second comparison circuit 354 (step B4).

  The signal strength detection circuit 351 receives the signal MS output from the ADC 31, and compares the signal strength of the signal MS with a first predetermined value (step B5). When the signal intensity of the signal MS is the same as the first predetermined value (Step B5; No, Step B6; No), the RFAGC voltage and the IFAGC voltage are not increased or decreased. On the other hand, when the signal strength of the signal MS is larger than the first predetermined value (step B5; No, step B6; Yes), the second comparison circuit 354 uses the RSSI value indicated by the signal RS and the threshold value output from the threshold value holding circuit 360. Compare (step B7). When the RSSI value is less than or equal to the second predetermined value (step B7; No), the gain distribution control circuit 355 determines whether or not the IFAGC voltage can be reduced. If it is possible (step B8; Yes), the RFAGC. The voltage is fixed and the IFAGC voltage is decreased (step B9). If the IFAGC voltage cannot be reduced (step B8; No), the gain distribution control circuit 355 reduces the RFAGC voltage and fixes the IFAGC voltage (step B11).

  Returning to step B7, when the RSSI value is larger than the second predetermined value (step B7; Yes), the gain distribution control circuit 355 decreases the RFAGC voltage and the IFAGC voltage (step B10).

  Returning to step B5, when the signal strength of the signal MS is smaller than the first predetermined value (step B5; Yes), the gain distribution control circuit 355 compares the RSSI value with the second predetermined value, and the RSSI value is equal to or less than the second predetermined value. In the case of (Step B12; No), it is determined whether or not the RFAGC voltage can be increased. If it is possible (step B13; Yes), the gain distribution control circuit 355 increases the RFAGC voltage and fixes the IFAGC voltage (step B14). When it is impossible (step B13; No), the gain distribution control circuit 355 fixes the RFAGC voltage and increases the IFAGC voltage (step B15).

  Returning to step B12, when the RSSI value is larger than the second predetermined value (step A10; Yes), the gain distribution control circuit 244 decreases the RFAGC voltage and increases the IFAGC voltage (step B16).

  By repeating the above operation, even when the reception apparatus 100 is moved and the reception state of the radio wave is changed, the amplification factors of the RF-AGC 22 and the IF-AGC 26 can be controlled to an appropriate amplification factor according to the RFAGC voltage. it can. For this reason, the reception quality of the received signal can be maintained at an optimum value, and the reception performance of the receiving apparatus 100 can be improved. According to the second embodiment, the second predetermined value can be set according to the amplification factor of the first amplification means. Thereby, based on the amplification factor of the first amplification means, it is possible to perform increase / decrease control of the amplification factor so as to effectively utilize the range in which the linearity of the first amplification means is maintained. Accordingly, for example, even when the reception apparatus is moved and the reception state of the radio wave is changed, the first amplifying unit always operates within a range in which the linearity is maintained. The amplification factors of the amplification unit and the second amplification unit can be automatically controlled to an appropriate amplification factor. As a result, even when the received signal changes from moment to moment, the optimum reception quality can always be ensured, and the reception performance of the receiving apparatus can be improved.

  Although the two embodiments have been described above, the receiving device, the receiving method, and the integrated circuit for the receiving device of the present invention are for receiving radio waves of mobile communication such as a mobile phone and a small vehicle-mounted television. Is preferred. However, the scope of application of the present invention is not limited to that for mobile communication as long as it is used in an environment / location where the reception status of radio waves changes.

1 is a block diagram showing a circuit configuration of a receiving device according to a first embodiment. The block diagram which shows the circuit structure of the AGC voltage control circuit of 1st Embodiment. The graph which showed the relationship between the signal level of signal S1, and the RSSI value which signal RS shows for every control voltage of RF-AGC22. The graph which showed the relationship between the signal level of signal S1 and the signal level of signal S2 for every AGC control voltage of RF-AGC22. The flowchart for demonstrating the process of the AGC voltage control circuit of 1st Embodiment. The block diagram which shows the circuit structure of the AGC voltage control circuit of 2nd Embodiment. The figure which shows an example of the threshold value table memorize | stored in the threshold value holding circuit of 2nd Embodiment. The flowchart for demonstrating the process of the AGC voltage control circuit of 2nd Embodiment.

Explanation of symbols

100 receiver 1 antenna 2 tuner circuit 21 LNA
22 RF-AGC
23, 25 BPF
24 RF mixer 26 IF-AGC
27 IF mixer 28 LPF
3 Demodulation circuit 31 ADC
32 FFT
33 Waveform Equivalent Circuit 34 Error Correction Circuit 35 AGC Voltage Control Circuit 4 RSSI Output Circuit

Claims (10)

First amplification means for amplifying a received signal received by the antenna;
Second amplifying means for extracting and amplifying a signal in the frequency band of the target selected station from the received signal amplified by the first amplifying means;
Demodulation means for demodulating the signal of the selected station amplified by the second amplification means;
Received signal strength detecting means for detecting the signal strength of the received signal received by the antenna;
Amplified signal strength detection means for detecting the signal strength of the signal of the selected station amplified by the second amplification means;
First comparing means for comparing the signal strength of the signal of the selected station detected by the amplified signal strength detecting means with a first predetermined value;
Second comparing means for comparing the signal strength of the received signal detected by the received signal strength detecting means with a second predetermined value;
AGC voltage control for controlling the amplification factor in the first amplification unit and the amplification factor in the second amplification unit based on the comparison result of the first comparison unit and the comparison result of the second comparison unit Means,
A receiving apparatus comprising: The AGC voltage control means includes:
It said first comparison means smaller than a predetermined value the signal strength is the first result of comparison the selected station signal by, and said second comparing means and said signal strength results were compared the received signal by a second 2. The receiving apparatus according to claim 1, wherein when the predetermined value is larger than the predetermined value, control is performed to decrease an amplification factor in the first amplification unit and increase an amplification factor in the second amplification unit. The AGC voltage control means includes:
It said first comparison means smaller than a predetermined value the signal strength is the first result of comparison the selected station signal by, and said second comparing means and said signal strength results were compared the received signal by a second When the gain is smaller than a predetermined value and the gain in the first amplifying means cannot be increased, the gain in the first amplifying means is maintained and the gain in the second amplifying means is increased. The receiving apparatus according to claim 1, wherein control is performed. The AGC voltage control means includes:
It said first comparison means smaller than a predetermined value the signal strength is the first result of comparison the selected station signal by, and said second comparing means and said signal strength results were compared the received signal by a second When the gain is smaller than a predetermined value and the gain in the first amplifying means can be increased, the gain in the first amplifying means is increased and the gain in the second amplifying means is maintained. The receiving apparatus according to claim 1, wherein control is performed. The AGC voltage control means includes:
Greater signal strength of a result of comparison the selected station signal from the first predetermined value by the first comparison means, and said second results were compared by the comparison means of the received signal of the signal intensity is the second 2. The receiving apparatus according to claim 1, wherein control is performed to reduce the amplification factor in the first amplification unit and the second amplification unit when the predetermined value is larger than the predetermined value. The AGC voltage control means includes:
Greater signal strength of a result of comparison the selected station signal from the first predetermined value by the first comparison means, and said second results were compared by the comparison means of the received signal of the signal intensity is the second When the gain is smaller than the predetermined value and the gain in the second amplifying means cannot be reduced, the gain in the first amplifying means is decreased and the gain in the second amplifying means is maintained. The receiving apparatus according to claim 1, wherein control is performed. The AGC voltage control means includes:
Greater signal strength of a result of comparison the selected station signal from the first predetermined value by the first comparison means, and said second results were compared by the comparison means of the received signal of the signal intensity is the second When the gain is smaller than the predetermined value and the gain in the second amplifying means can be reduced, the gain in the first amplifying means is maintained and the gain in the second amplifying means is reduced. The receiving apparatus according to claim 1, wherein control is performed.   The receiving apparatus according to claim 2, wherein the second predetermined value is variable in accordance with an amplification factor in the first amplifying unit. A first amplification step for amplifying a received signal received by an antenna;
A second amplification step of extracting and amplifying a signal in a frequency band of a target selection station from the reception signal amplified by the first amplification step;
A demodulation step of demodulating the signal of the selected station amplified by the second amplification step;
A received signal strength detecting step of detecting a signal strength of a received signal received by the antenna;
And amplifying the signal intensity detecting step of detecting a signal strength of said second amplified selected station signal by amplification step,
A first comparison step of comparing the signal strength of the signal of the selected station detected by the amplified signal strength detection step with a first predetermined value;
A second comparison step of comparing a signal strength of the reception signal detected by the reception signal strength detection step with a second predetermined value;
AGC voltage control for controlling the amplification factor in the first amplification step and the amplification factor in the second amplification step based on the comparison result of the first comparison step and the comparison result of the second comparison step Process,
A receiving method comprising: A first amplifier circuit that amplifies a received signal received by a connected antenna;
A second amplifier circuit that extracts and amplifies a signal in a frequency band of a target selection station from the reception signal amplified by the first amplifier circuit;
A demodulation circuit for demodulating the signal of the selected station amplified by the second amplification circuit;
A received signal strength detection circuit for detecting a signal strength of a received signal received by the antenna;
An amplified signal strength detection circuit for detecting the signal strength of the signal of the selected station amplified by the second amplifier circuit;
A first comparison circuit that compares the signal strength of the signal of the selected station detected by the amplified signal strength detection circuit with a first predetermined value;
A second comparison circuit that compares the signal strength of the received signal detected by the received signal strength detection circuit with a second predetermined value;
AGC voltage control for controlling the gain in the first amplifier circuit and the gain in the second amplifier circuit based on the comparison result of the first comparator circuit and the comparison result of the second comparator circuit Circuit,
An integrated circuit for a receiving device, comprising:

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