JP2005142948A - Variable gain amplifier, and receiving device and reception control method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable gain amplifier, a receiving device, and a reception control method using the amplifier, which enable lowering the specification of a tertiary output distortion intercept point (OIP3) of a primary amplifier and reducing power consumption for raising the OIP3 specification. <P>SOLUTION: The variable gain amplifiers 107 and 108 can control gain for input signals. A first control signal C1 switches between a circuit for consecutively controlling gain and a circuit for outputting a fixed gain by a second control signal C2. Consequently, a gain by a primary amplifier 100 can be controlled when the interfering wave of an adjacent channel is large, and the specification of the OIP3 which becomes an index of linearity of the primary amplifier 100, an amplifier, a frequency converter and the like serving as a circuit to the input end of a filter can be controlled to a low level. Power consumption for raising the specification of the OIP3 can also be suppressed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable gain amplifier, a receiving apparatus using the same, and a reception control system.

As an example of a variable gain amplifier that controls the level of a baseband signal of a receiving apparatus to be constant and a receiving apparatus using the variable gain amplifier, the one shown in FIG. 14 is known. The following documents are introduced as references.
"A 5-GHz CMOS Transceiver for IEEE 802.11a Wireless LAN Systems" IEEE JSSC VOL.37. NO.12. DECEMBER2002

  FIG. 14 is a simplified diagram of the receiving apparatus described in the above-mentioned reference, and a first-stage amplifier 902 that can switch in two stages for amplifying a radio frequency signal (RF signal) input from the input terminal 901, and a first frequency conversion. An intermediate frequency variable gain amplifier (IFVGA) 904 for further amplifying the output of the amplifier 903, a circuit 905 for a second frequency converter and a filter for performing a quadrature conversion to the I and Q signals and performing amplification, signal wave selection, etc. 906, I and Q are variable gain amplifiers (BBVGA) for amplifying baseband signals 907, 908, I and Q, respectively, and subsequent circuits 909 and 910.

  FIG. 15 is a level diagram of the received signal in the receiving apparatus. In the receiving apparatus as described above, for example, it is necessary to receive the desired wave even when the interference wave in the adjacent channel is much larger than the desired wave to be received. When the RF signal input from the input terminal is relatively small, the first-stage amplifier amplifies the signal with a high gain (solid line), but also a disturbing wave in the adjacent channel is similarly amplified (broken line) along with the desired wave. For example, in a receiving apparatus such as a wireless LAN transceiver, it is necessary to allow an interference wave as large as 40 dBc in the reception sensitivity of a desired wave. For this reason, in order to receive a desired wave without reducing the bit error rate (BER), an amplifier, a frequency converter, or the like that is a circuit up to the input end of the filter has an output third-order distortion intercept point that is an index of linearity. It is necessary to design (OIP3) higher than a certain value from the output in which the interference wave is amplified.

However, in a conventional receiving apparatus, an amplifier, a frequency converter, and the like, which are circuits up to the input end of the filter, amplify both a received desired wave and an interference wave in an adjacent channel with high gain. For this reason, amplifiers, frequency converters, and the like that are circuits up to the input end of the filter need to be designed with high OIP3 specifications, and there is a problem that a large amount of current is required to improve linearity. It was.
In order to solve such a problem, a method of continuously controlling the gains of the first-stage amplifier and the subsequent-stage amplifier is known (refer to Japanese Patent Laid-Open No. 2001-28553).

JP 2001-28553 A A 5-GHz CMOS Transceiver for IEEE 802.11a Wireless LAN Systems "IEEE JSSC VOL.37. NO.12. DECEMBER2002

  However, in the method described in Patent Document 1, when the control lines for controlling the first-stage amplifier and the latter-stage amplifier are the same, when it is necessary to allow an interference wave as large as 40 dBc at the reception sensitivity of a desired wave, Since the gain is small, the specification of OIP3 of the first stage amplifier cannot be kept sufficiently low, and the circuit design of the first stage amplifier and the subsequent stage amplifier is restricted.

  The present invention has been devised in view of the above circumstances, and the object thereof is to reduce the specification of the OIP3 of the first stage amplifier, and also to suppress the current consumption for raising the specification of the OIP3. It is an object to provide a variable gain amplifier, a receiving apparatus using the variable gain amplifier, and a reception control method.

In order to achieve the above object, the present invention provides a variable gain amplifier capable of gain control with respect to an input signal, wherein the gain can be continuously variable by a second control signal, and And a second mode in which a constant gain is maintained by a control signal of 2, and switching between the first mode and the second mode is performed by a first control signal. Features.
The present invention further includes a first amplifier circuit whose gain is continuously variable by a second control signal in order to realize the first aspect, and outputs the input signal via the first amplifier circuit. And a second signal path that outputs the input signal via the second amplifier circuit, the second signal circuit having a constant gain to realize the first mode. And a first switch circuit that switches between the first signal path and the second signal path in accordance with a first control signal.

  According to the present invention, a third amplifier circuit interposed between the input terminal and the output terminal and a second control signal are input, and the gain of the third amplifier circuit is continuously variable by the second control signal. A first control circuit that can be controlled, a second control circuit that receives a second control signal, and controls the third amplifier circuit so that the gain is constant according to the second control signal; And a second switch circuit interposed between the second control signal and the first control circuit, and between the second control signal and the second control circuit, respectively, and switched according to the first control signal. And a second switch circuit that can be switched.

  In addition, the present invention is a variable gain amplifier capable of gain control with respect to an input signal, wherein a change width of continuous gain control by the second control signal is switched by the first control signal.

  The present invention includes a plurality of fourth amplifier circuits that are continuously variable in gain by a second control signal and have different gain change widths, and each of the fourth amplifier circuits is controlled by a second control signal. There is also a case where any one of the amplifier circuits is selectively switched and the input signal is output via the selected fourth amplifier circuit.

  In the present invention, the third amplifier circuit interposed between the input terminal and the output terminal and the second control signal are respectively input, and the third amplifier circuit is controlled so that the change width of the gain control is different. A plurality of third control circuits, a switch circuit group interposed between the second control signal and the plurality of third control circuits, respectively, to select one of the plurality of third control circuits And a switch circuit group whose switching mode is switched by the first control signal.

  Further, the present invention is a receiving device having a first stage amplifier, a frequency converter, a filter, and a rear stage amplifier, wherein the rear stage amplifier is the variable gain amplifier according to any one of claims 1 to 6, And amplifying to a predetermined output signal level.

  In the case where the variable gain amplifier according to any one of claims 1 to 3 is provided, when the desired wave to be received is small, the gain of the entire receiving device is increased in order to receive the signal. When the variable gain amplifier in the baseband frequency band in the later stage is made constant at a high gain, and the first stage amplifier in the first stage among the receivers is continuously variable in gain configuration, when the interference wave of the adjacent channel is large Thus, the gain of the first stage amplifier can be suppressed, and the specifications of the OIP3 that is an index of linearity of the first stage amplifier, the amplifier that is a circuit up to the input terminal of the filter, the frequency converter, and the like can be suppressed to a low level. In addition, current consumption for increasing the specifications of OIP3 can be suppressed.

  In the case where the variable gain amplifier according to any one of claims 4 to 6 is provided, when the desired wave to be received is small, the gain of the entire receiving device is increased in order to receive the signal. A variable gain amplifier in a baseband frequency band in a relatively subsequent stage suppresses the change width with a relatively high gain, and the first stage amplifier in the first stage in the receiving apparatus has a variable gain configuration with a continuously large change width. When the channel interference is large, the gain of the first stage amplifier can be suppressed, and the specifications of OIP3, which is an index of linearity, such as the first stage amplifier, the amplifier up to the input terminal of the filter, and the frequency converter are reduced. Can be suppressed. In addition, current consumption for increasing the specifications of OIP3 can be suppressed.

  In addition, the present invention is a reception control system that performs gain control on a high-frequency input signal at least in each of the preceding stage and the subsequent stage, and when the desired wave to be received is small, the gain control is performed so that the gain is constant at a high gain in the subsequent stage. The former stage may be characterized in that gain control is performed so that a variable gain configuration is continuously obtained. In addition, when the desired wave to be received is small, the subsequent stage suppresses the change width with a relatively high gain. The gain control may be performed as described above, and in the preceding stage, the gain control may be performed so that a variable gain configuration having a continuously large change width is obtained.

  According to the present invention, the specification of OIP3 can be kept low, and current consumption for raising the specification of OIP3 can also be suppressed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a variable gain amplifier and a receiving apparatus using the same according to the present invention will be described below in detail with reference to the accompanying drawings.
(Embodiment 1)
[Circuit configuration of receiving apparatus]
FIG. 1 is a block diagram of the main part of a receiving apparatus according to the present invention. In the case of a direct conversion receiving device, the receiving device 1 can be switched between an antenna (not shown) and two stages for amplifying a radio frequency signal (RF signal) input from the antenna via the input terminal 101, respectively. First-stage amplifier (RFVGA) 100 that is continuously variable in gain, frequency converter 104 that performs frequency conversion on the output of first-stage amplifier 100 and orthogonally converts the output to I and Q signals, and I signal output of frequency converter 104 The circuit 105 further including a filter, the Q signal output of the frequency converter 104 is further amplified, the circuit 106 further includes a filter, and the variable gain amplifier (BBVGA) 107 that amplifies the I baseband signal. A variable gain amplifier (BBVGA) 108 that amplifies the Q baseband signal, a post-stage circuit 109 for I signal, And issue a subsequent circuit 110, a signal generation circuit 111 for outputting a first control signal C1 and the second control signal C2, and a signal level detection circuit 112. which detects the signal level of the received signal. As will be described later, the signal generation circuit 111 generates and outputs a first control signal C1 and a second control signal C2 according to the received signal level detected by the signal level detection circuit 112.

  The first-stage amplifier 100 includes a first amplifier circuit 102 (corresponding to the first circuit) and a second amplifier circuit 103 (corresponding to the second circuit), and the first amplifier 100 is controlled by the first control signal C1. The amplifier circuit 102 and the second amplifier circuit 103 can be selectively switched. Specifically, as shown in FIG. 2, the power supply line L1 of the bias circuit 122 supplied to the first amplifier circuit 102 is provided with a switch SW1 for switching between the power supply voltage Vcc and the ground. A switch SW2 for switching between the power supply voltage Vcc and the ground is provided in the power supply line L2 of the bias circuit 123 supplied to the amplifier circuit 103, and the first control signal C1 is commonly applied to these switches SW1 and SW2. For example, when the first control signal C1 is at a high level, the switch SW1 is switched to the power supply voltage Vcc side, and the switch SW2 is switched to the ground side, and when the first control signal C1 is at a low level, The switch SW1 is switched to the ground side, and the switch SW2 is switched to the power supply voltage Vcc side. Accordingly, as described above, either the first amplifier circuit 102 or the second amplifier circuit 103 is selectively switched by the first control signal C1.

  Here, the first amplifier circuit 102 is a circuit that outputs high gain, the second amplifier circuit 103 is a circuit that outputs low gain, and the first amplifier circuit 102 and the second amplifier circuit 103 are either Also, the gain is continuously variable by the second control signal C2. Therefore, for example, when a small signal is input, an amplifier 102 having a high gain and a small NF generation is selected to obtain a noise figure (NF), and when a relatively large signal is input, linearity is emphasized. The selected amplifier 103 is selected.

  The variable gain amplifiers 107 and 108 can switch between performing a continuous variable gain based on the second control signal C2 or making the gain constant in accordance with the first control signal C1 provided from the signal generation circuit 111. It is configured. FIG. 3 shows the variable gain range of the variable gain amplifiers 107 and 108. The gain change width by the second control signal C2 can be switched by the first control signal C1, and the solid line in FIG. 3 obtains a constant gain by the first control signal C1. Also, the broken line in FIG. 3 is continuously changed by the first control signal C1, and the gain is continuously changed by the second control signal C2.

A specific configuration of the variable gain amplifier 107 (108) is shown in FIG. The variable gain amplifier 107 (108) has two types of control circuits 702 and 703 having variable gain characteristics arranged in parallel, and switches 704 and 705 (corresponding to a second switch circuit) that serve as signal paths by the first control signal C1. When applied to the second embodiment to be described later, it corresponds to a switch circuit group) and is configured to select whether to use the control circuit 702 or the control circuit 703. The gain of the variable gain amplifier circuit 701 is continuously changed by the second control signal C2 via the control circuit 702 or the control circuit 703. In the receiving apparatus according to the first embodiment, the control circuits 702 and 703 are changed. Since one of the two (corresponding to the first control circuit and the second control circuit) outputs only a constant value regardless of the second control signal C1, the variable gain amplifier circuit 701 (corresponding to the third amplifier circuit) is output. ) Is constant, and the other of the control circuits 702 and 703 is a circuit that realizes continuous variable gain according to the second control signal C2.
In the variable gain amplifiers 407 and 408 of the receiving apparatus according to the second embodiment to be described later, one of the control circuits 702 and 703 (corresponding to the third control circuit) has a gain of the second control signal C2. A control signal for increasing the continuous variable range is output to the variable gain amplifier circuit 701, and the other of the control circuits 702 and 703 (corresponding to the third control circuit) decreases the continuous variable range of the gain by the second control signal. The control signal is output to the variable gain amplifier circuit 701.

  A specific circuit configuration of the variable gain amplifier 107 is shown in FIG. The variable gain amplifier 108 has a circuit configuration similar to that of the variable gain amplifier 107. The gain of the variable gain amplifier 107 continuously changes depending on the current supply amounts of the transistors Tr1 and Tr2, but the current supply amounts of the transistors Tr1 and Tr2 can be determined by the pass gates P1 and P2 and the transistors Tr3 and Tr4. ON / OFF of the pass gate and ON / OFF of the transistor are determined by the control signal C1 of 1. The variable gain amplifier 107 is variable in gain by the second control signal C2 when the pass gate is ON, and the transistors Tr3 and Tr4 are turned ON when the pass gate is OFF, so that the current supply amount of the transistors Tr1 and Tr2 of the variable gain amplifier 107 is constant. Become. For this reason, the variable gain amplifier 107 obtains a constant gain regardless of the second control signal.

[Reception control operation of receiving device]
Next, the reception control operation of the reception apparatus having the above configuration will be described.
FIG. 6 is a flowchart of the reception control operation of the receiving apparatus. The level of the received signal is detected by the signal level detection circuit 112 (step S1). If the level of the received signal is small, the process proceeds to step S2, and the signal generation circuit 111 receives the first control signal C1 and the second control signal C2. This is given to the first stage amplifier 100. As a result, the first-stage amplifier 100 is switched to the first amplifying circuit 102 that outputs a high gain, and has a configuration capable of continuously variable gain by the second control signal C2. At the same time, the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the variable gain amplifiers 107 and 108. Thereby, the variable gain amplifiers 107 and 108 are switched to the control circuit 702 side, and a constant gain is output by the second control signal C2. As a result, the signal level of the desired wave changes to the target level P of the output level of the variable gain amplifiers 107 and 108 as shown by the line M1 in FIG. Here, since the variable gain amplifiers 107 and 108 are configured to amplify the signal level, the gain of the first stage amplifier 100 can be set to a gain that is not so high. Therefore, the signal level of the disturbing wave is lower than the conventional example in the output level P1 from the first-stage amplifier 100 of the disturbing wave, as shown by the line M2 in FIG. The specification level N1 of the OIP3 of the amplifier circuit 102) can be suppressed compared to the specification level N2 of the conventional OIP3. As a result, there is an effect that it is not necessary to consume a large amount of current in order to improve OIP3.

  When the level of the received signal is small, the gain of the desired wave having the maximum level among the small levels is controlled by the amplifier circuit 102 so that the signal level is reduced to P2, as indicated by the line M3 in FIG. Thereafter, it changes to the target level P through the same route as the line M2. In this case, since the level of the disturbing wave is also reduced by the amplifier circuit 102, the specification level N1 of the OIP3 is sufficiently satisfied, and no problem occurs.

  In step S1, when the level of the received signal is high, the process proceeds to step S3, and the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the first stage amplifier 100. As a result, the first-stage amplifier 100 is switched to the second amplifier circuit 103 that outputs a low gain, and has a continuously variable gain configuration based on the second control signal C2. At the same time, the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the variable gain amplifiers 107 and 108. As a result, the variable gain amplifiers 107 and 108 are switched to the control circuit 703 side, and have a variable gain configuration continuously by the second control signal C2. As a result, the signal level of the desired wave is reduced by the first-stage amplifier 100 as shown by the line M4 in FIG. 8, passes through the frequency converter and filter while maintaining the signal level, and is changed by the variable gain amplifiers 107 and 108. It further decreases and changes to the target level P. The disturbing wave at this time changes as shown by a line M5 in FIG.

  When the level of the received signal is large, the desired wave having the minimum level among the large levels is increased by the amplifier circuit 102 as shown by the line M6 in FIG. 8, and the frequency conversion is performed while maintaining the signal level. Through the filter and the filter, and further increased by the variable gain amplifiers 107 and 108 to the target level P.

  In this way, a circuit design with a high degree of freedom can be achieved by controlling the gain distribution by the first stage amplifier and the subsequent stage amplifier (corresponding to the variable gain amplifiers 107 and 108) and guiding the desired wave to the target level P. Is possible. In particular, by controlling the gain when the signal level is small, the specification level of OIP3 can be suppressed as compared with the conventional example. Therefore, it is possible to easily design the circuit of the first stage amplifier with low current consumption. Become.

(Embodiment 2)
[Circuit configuration of receiving apparatus]
FIG. 9 is a main part configuration diagram of a receiving apparatus according to Embodiment 2 of the present invention. In the second embodiment, parts corresponding to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the second embodiment, variable gain amplifiers 407 and 408 are used instead of the variable gain amplifiers 107 and 108 of the first embodiment. The variable gain amplifier 407 and the variable gain amplifier 408 have the same circuit configuration. The variable gain amplifiers 407 and 408 are continuously variable in gain by the second control signal C2 supplied from the signal generation circuit 111, and gain is increased by the first control signal C1 supplied from the signal generation circuit 111. The width of change is configured to be switched. That is, as shown in FIG. 10, the gain change width by the second control signal C2 is a continuous gain change with a relatively small change width as shown by the solid line in FIG. 10 by the first control signal C1. It is possible to switch between a case of performing and a case of performing a continuous gain change with a relatively large change width as indicated by a broken line. The specific circuit configuration of the variable gain amplifiers 407 and 408 is basically the same as the configuration shown in FIG. 4 of the first embodiment. However, in the second embodiment, as described above, one of the control circuits 702 and 703 (corresponding to the third control circuit) controls to increase the continuous variable range of the gain by the second control signal C2. The signal is output to the variable gain amplifier circuit 701, and the other of the control circuits 702 and 703 outputs to the variable gain amplifier circuit 701 a control signal for reducing the continuous variable range of the gain by the second control signal C2.

[Reception control operation of receiving device]
Basically, the same reception control operation as in the first embodiment is performed. That is, when the level of the received signal is detected by the signal level detection circuit 112 and the level of the received signal is small, the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the first stage amplifier 100. . As a result, the first-stage amplifier 100 is switched to the first amplifier circuit 102 that outputs a high gain, and has a continuously variable gain configuration by the second control signal C2. At the same time, the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the variable gain amplifiers 407 and 408. As a result, the variable gain amplifiers 407 and 408 are switched to the control circuit 702 side, and can be continuously variable gained by the second control signal C2. As a result, the signal level of the desired wave changes to the target level P of the output level of the variable gain amplifiers 407 and 408, as indicated by the line M8 in FIG. Here, since the variable gain amplifiers 4107 and 408 are configured to amplify the signal level, the gain of the first-stage amplifier 100 can be set to a modest gain. Therefore, the signal level of the disturbing wave is lower than the conventional example in the output level P2 from the first-stage amplifier 100 of the disturbing wave, as shown by the line M8 in FIG. The specification level N1 of the OIP3 of the amplifier circuit 102) can be suppressed compared to the specification level N2 of the conventional OIP3. As a result, there is an effect that it is not necessary to consume a large amount of current in order to improve OIP3.

  When the level of the received signal is small, the gain of the desired wave having the maximum level among the small levels is controlled by the amplifier circuit 102 so that the signal level is reduced to P3 as shown by the line M9 in FIG. After that, the signal passes through the frequency converter and the filter while maintaining the signal level, and further increases by the variable gain amplifier circuit 701 and changes to the target level P. In this case, since the level of the disturbing wave is also reduced by the amplifier circuit 102, the specification level N1 of the OIP3 is sufficiently satisfied, and no problem occurs.

  When the level of the received signal is high, the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the first stage amplifier 100. As a result, the first-stage amplifier 100 is switched to the second amplifier circuit 103 that outputs a low gain, and has a continuously variable gain configuration based on the second control signal C2. At the same time, the signal generation circuit 111 supplies the first control signal C1 and the second control signal C2 to the variable gain amplifiers 407 and 408. As a result, the variable gain amplifiers 407 and 408 are switched to the control circuit 702 side, and continuously have a variable gain configuration by the second control signal C2. As a result, the signal level of the desired wave is reduced by the first-stage amplifier 100 as shown by the line M10 in FIG. 12, passes through the frequency converter and the filter while maintaining the signal level, and is further increased by the variable gain amplifier circuit 701. Decrease and change to target level P. The interference wave at this time changes as indicated by a line M11 in FIG.

  Further, when the level of the received signal is large, the desired wave having the minimum level among the large levels is increased by the amplifier circuit 103 as shown by the line M12 in FIG. 12, and the frequency conversion is performed while maintaining the signal level. Through the filter and the filter, and further increased by the variable gain amplifier circuit 701 until the target level P is reached.

  Thus, also in the second embodiment, the specification level of OIP3 can be suppressed as compared with the conventional example by the gain control when the signal level is small as in the first embodiment, and therefore, the current consumption can be reduced. The circuit design of the first stage amplifier can be easily performed.

  In the second embodiment, the variable range of the entire apparatus can be made larger than that in the first embodiment. In other words, in the first embodiment, when the signal level is low, the gain of the subsequent amplifier (corresponding to the variable gain amplifiers 107 and 108) is constant, so that the variable width of the entire apparatus is narrowed accordingly. Therefore, in the second embodiment, even when the signal level is small, the variable width of the entire apparatus can be increased by making the gain of the subsequent amplifier (equivalent to the variable gain amplifiers 407 and 408) variable. As a result, the degree of freedom in circuit design increases.

(Embodiment 3)
Another configuration of the variable gain amplifier 107 is shown in FIG. Note that the variable gain amplifiers 108, 407, and 408 have the same configuration as the variable gain amplifier 107. The variable gain amplifier 107 according to the third embodiment includes a variable gain amplifier circuit 801 (corresponding to a first amplifier circuit) having two types of variable gain characteristics, and a variable gain amplifier circuit 802 (corresponding to a second amplifier circuit). Are switched in parallel, and switches 803 and 804 (corresponding to the first switch circuit) serving as signal paths are switched by the first control signal C1 to use either the variable gain amplifier circuit 801 or the variable gain amplifier circuit 802. Is configured to select. The variable gain amplifier 801 continuously changes the gain by the second control signal C2, but the variable gain amplifier circuit 802 has a constant gain regardless of the second control signal C2.
When the configuration of FIG. 13 is applied to the variable gain amplifier 407, either one of the variable gain amplifier circuits 801 and 802 (corresponding to the fourth control circuit) has an output whose gain is obtained by the second control signal C2. The other of the variable gain amplifying circuits 801 and 802 has a small continuous variable range of gain by the second control signal C2.

(Other matters)
(1) In the embodiment of the present invention, the direct conversion receiving apparatus has been described. However, the present invention can also be applied to a heterodyne receiving apparatus that performs frequency conversion twice.
(2) In the embodiment of the present invention, the two variable gain amplifiers 107 and 108; 407 and 408 are used in the receiving apparatus, but can be applied to the transmitting apparatus. Further, the variable gain amplifier according to the present invention can be applied to variable gain amplifiers of other electronic devices in addition to the transmission device and the reception device.

  The present invention can be implemented in a receiving terminal device such as a wireless LAN transceiver.

It is a principal part block diagram of the receiver of Embodiment 1 which concerns on this invention. 3 is a specific circuit diagram of the first stage amplifier 100. FIG. It is a figure which shows the variable gain range of variable gain amplifier 107,108. It is a figure which shows the specific structure of the variable gain amplifier 107 (108). It is a figure which shows the specific circuit structure of the variable gain amplifier 107 (108). It is a flowchart of the reception control operation | movement of a receiver. 3 is a level diagram when the signal signal in the first embodiment is small. 3 is a level diagram when the signal signal in the first embodiment is large. It is a principal part block diagram of the receiver which concerns on Embodiment 2 of this invention. FIG. 6 is a diagram illustrating a gain change width. It is a level diagram in case the signal signal in Embodiment 2 is small. It is a level diagram in case the signal signal in Embodiment 2 is large. 6 is a diagram illustrating another configuration of the variable gain amplifier 107. FIG. It is a simplified diagram of a conventional receiving apparatus. It is the level diagram of the received signal in the receiver of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... First stage amplifier 101 ... Input terminal 102 ... 1st amplifier circuit 103 ... 2nd amplifier circuit 104 ... Frequency converter 105, 106 ... Filter 107, 108, 407, 408... Variable gain amplifiers 109 and 110... Subsequent circuit 111... Signal generation circuits 702 and 703... Control circuits 701, 801 and 802.

Claims (10)

A variable gain amplifier capable of gain control with respect to an input signal,
A first mode in which the gain can be continuously controlled to be variable by the second control signal; and a second mode in which the gain is held at a constant gain by the second control signal. A variable gain amplifier characterized in that the switching of the second mode is performed by the first control signal. A first signal that includes a first amplifier circuit whose gain is continuously variable by a second control signal in order to realize the first aspect, and that outputs the input signal via the first amplifier circuit. Route,
A second signal path for outputting the input signal via the second amplifier circuit, the second amplifier circuit having a constant gain so as to realize the second mode;
A first switch circuit that switches between the first signal path and the second signal path according to the first control signal;
The variable gain amplifier according to claim 1, comprising: A third amplifier circuit interposed between the input terminal and the output terminal;
A first control circuit that receives the second control signal and controls the third amplifier circuit so that the gain can be continuously varied by the second control signal;
A second control circuit that receives the second control signal and controls the third amplifying circuit to have a constant gain by the second control signal;
A second switch circuit interposed between the second control signal input terminal and the first control circuit, and between the second control signal input terminal and the second control circuit, respectively, A second switch circuit whose switching mode is switched by a control signal of
The variable gain amplifier according to claim 1, comprising: A variable gain amplifier capable of gain control with respect to an input signal,
A variable gain amplifier characterized in that a change width of continuous gain control by the second control signal is switched by the first control signal. A plurality of fourth amplifying circuits which are continuously variable in gain by the second control signal and have different gain change widths;
In accordance with a second control signal, one of the fourth amplifier circuits is selectively switched, and the input signal is output via the selected fourth amplifier circuit. The variable gain amplifier according to claim 4. A third amplifier circuit interposed between the input terminal and the output terminal;
A plurality of third control circuits, each of which receives the second control signal, and controls the third amplifier circuit so that a gain control change width is different;
A group of switch circuits interposed between the second control signal and the plurality of third control circuits, respectively, in order to select one of the plurality of third control circuits, according to the first control signal; A group of switch circuits in which switching modes are switched;
The variable gain amplifier according to claim 4, comprising: A receiving device having a first stage amplifier, a frequency converter, a filter, and a subsequent stage amplifier,
7. The receiving apparatus according to claim 1, wherein the post-stage amplifier is a variable gain amplifier according to claim 1, and amplifies to a predetermined output signal level in cooperation with the first-stage amplifier.   The first-stage amplifier can be switched between a first circuit that outputs a high gain and a second circuit that outputs a low gain by a first control signal, and the first circuit and the second circuit. The receiving apparatus according to claim 7, wherein both are circuits capable of continuous gain control by the second control signal. A high frequency input signal is a reception control method that performs gain control at least in each of the front and rear stages,
A reception control system characterized in that when a desired wave to be received is small, gain control is performed so that the gain is constant at a high gain in the subsequent stage, and gain control is performed continuously in a variable gain configuration in the previous stage. A high frequency input signal is a reception control method that performs gain control at least in each of the front and rear stages,
When the desired signal to be received is small, gain control is performed so as to suppress the change width with a relatively high gain in the subsequent stage, and gain control is performed so that a variable gain configuration with a continuously large change width is obtained in the previous stage. Reception control method.

Images