JP2002190995A - High-frequency signal processor and transmitter/ receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase in power consumption in a receiver due to always flowing the excessive power consumption even when the input level range of a downstream signal is around the lowest value in a transmitter/ receiver capable of making two way communication. SOLUTION: An IF-AGC voltage is monitored to control the power consumption of an active circuit so that the power consumption of the active circuit provided from an input/output connector to an IF gain control amplifier is appropriately controlled according to the level of an RF input signal. Also, if the apparatus has a function of transmission reception, a gain control signal of a transmission signal is monitored to control the power consumption of the active circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal device connected to, for example, a cable television network (CATV network). The present invention relates to a transmission / reception device that can be used.

[0002]

2. Description of the Related Art In recent years, with the advancement of multimedia and digitalization of broadcasting technology and communication technology, integration of broadcasting and communication technology fields has been realized. For example, a CATV line has a larger data transmission capacity than a telephone line.
It is conceivable to construct a network using a line and provide a data communication service via the Internet.

In this service, an interface with a CATV line called a cable modem is installed at a subscriber's house, a personal computer as a data communication device is connected to the cable modem, and a user can connect to an external network such as the Internet via a CATV broadcasting center. So that you can access it.

An example of such a cable modem having a receiving circuit for receiving a digitally modulated broadcast signal (downstream signal) and a transmitting circuit for sending out an upstream signal will be described with reference to FIG. I do.

In FIG. 1, a digitally modulated high-frequency signal (hereinafter referred to as an RF signal), which is a downstream signal, is input from an input / output connector 1 and is passed through a duplexer 2 to an RF variable attenuator 3.
And a first high-frequency amplifier 4 (hereinafter referred to as RF
Amplifier 4), a band-pass filter 5 (hereinafter referred to as B
PF5) and a second high-frequency amplifier 6 (hereinafter, RF amplifier 6).

The mixer 7 mixes the RF signal and the signal from the local oscillator 8 to perform frequency conversion, and outputs an intermediate frequency signal (hereinafter, IF signal). The IF signal frequency-converted by the mixer 7 is supplied to an IF gain control amplifier 11 via a first IF amplifier 9 and an IF band BPF 10. The output from the IF gain control amplifier 11 is
Is output from an IF signal output terminal 13 through an IF amplifier 12.

The IF output from the IF signal output terminal 13
The signal is input to an analog-to-digital converter 14 (hereinafter, AD converter 14), and the AD converter 14
The F signal is converted into a digital signal, and the demodulator 15 at the next stage performs digital demodulation.

[0008] A digital output from the AD converter 14 is input to a level detector 16, and the output of the level detector 16 is supplied to an AGC voltage generation circuit 17. The AGC voltage generation circuit 17 generates an IF-AGC voltage and an RF-AGC voltage, and supplies the IF-AGC voltage to the IF gain control amplifier 11 and the RF variable attenuator 3 via terminals 18 and 19, respectively.
Supply GC voltage and RF-AGC voltage. Thus RF
The gain of the variable attenuator 3 and the gain of the IF gain control amplifier 11 are controlled, and control is performed so that the input level of the AD converter 14 is optimized.

The operation of the RF-AGC and the IF-AGC is as shown in FIG. 8. In the region where the input level of the RF signal is low, the RF-AGC does not operate, only the IF-AGC operates, and the input of the RF signal is performed. RF-A in the high level area
GC operates, and IF-AGC becomes constant. FIG.
, Characteristic A indicates the input level of the first RF amplifier 4, characteristic B indicates the signal attenuation by the IF gain control amplifier 11, and characteristic C indicates the signal attenuation by the RF variable attenuator 3.

On the other hand, a high-frequency signal, which is an upstream signal, is input to a terminal 20, is supplied to a duplexer 2 via a gain control amplifier 21 and a band-pass filter 22, and is sent to a CATV center via an input / output connector 1 and a cable. An uplink signal is transmitted to the station. The gain control amplifier 21
Is for performing intermittent control of the transmission signal and level control of the transmission signal by the control signal supplied to the terminal 23.
Reference numeral 24 denotes a terminal for supplying + B voltage.
The block indicated by is a receiving circuit, and the block indicated by reference numeral 200 is a transmitting circuit.

As an example of a high-frequency device having a transmitting / receiving function, Japanese Patent Application No.
198475.

The downstream signal input to the input / output connector 1 is usually a high frequency signal of 90 to 860 MHz, and the level of the downstream signal at the input terminal of the cable modem is usually from -15 dB (mV) to +15 dB (mV). ) The degree is weak. The upstream signal is usually a high-frequency signal of about 5 to 65 MHz, and the level of the upstream signal is +8 to +58 dB (mV) at the output terminal of the cable modem.

By the way, as described above, in the receiving apparatus,
As described above, it is necessary to guarantee the range of 30 dB (mV) at the minimum for the downstream signal input. Therefore, the RF amplifier 4 secures the distortion performance that can withstand even when the input signal level is expected to be the maximum level. So that a relatively large bias current always flows regardless of a change in the input level.

Further, another RF amplifier 6, mixer 7, IF
Similarly, the amplifier 9 does not change the bias setting even if the input level changes, and the current consumption does not change. Therefore, in the conventional receiving apparatus, even when a signal whose input level range is near the lower limit is input, an excessively large current is constantly flowing in order to secure distortion performance.

[0015] Considering the upstream signal, when the input level of the downstream signal is near the lower limit, it is generally the case that the upstream signal is located on a trunk line far from the CATV center station. Requires large current consumption. In other words, as the downstream signal level is lower, the gain control amplifier 21 of the upstream signal requires a larger current consumption.

Therefore, considering such a point, even when the input level range of the downstream signal is near the lower limit, constantly flowing an excessive current consumption increases the current consumption of the receiving apparatus and increases the current consumption of the upstream signal. At the time of transmission, the current consumption further increases.

[0017]

As described above, in the conventional receiving apparatus, even when the input level range of the downstream signal is near the lower limit, excessive current consumption is constantly flowing, so that the current consumption of the receiving apparatus is increased. Will do. In addition, current consumption is further increased when transmitting an uplink signal.

In view of the above circumstances, the present invention appropriately controls the current consumption of an active circuit such as an amplifier existing between an input / output connector and an IF gain control amplifier according to the level of an RF input signal. It is an object of the present invention to provide a receiving apparatus in which an increase in the number of received signals is suppressed.

[0019]

According to the present invention, there is provided an input terminal to which a high frequency signal is inputted, and a first terminal supplied to the input terminal.
And a gain control circuit for controlling the gain of the intermediate frequency signal by a gain control signal and outputting the same, wherein a plurality of the plurality of intermediate frequency signals are provided between the input terminal and the gain control circuit. A receiving circuit including an active circuit, and current control means for detecting the gain control signal supplied to the gain control circuit and controlling current consumption of the active circuit in accordance with the gain control signal. It is a high-frequency signal processing device characterized by the following.

The present invention also provides an input / output terminal for inputting / outputting a high-frequency signal, a circuit for receiving the first high-frequency signal supplied to the input / output terminal and converting it to an intermediate frequency, A receiving circuit including a gain control circuit for controlling and outputting a gain, including a plurality of active circuits between the input / output terminal and the gain control circuit, and an input terminal to which a second high-frequency signal for transmission is supplied And a control terminal to which a gain control signal for controlling the gain of the second high-frequency signal is supplied,
A transmission circuit that controls the second high-frequency signal supplied to the input terminal by the gain control signal and supplies the input / output terminal to the input / output terminal; and detects the gain control signal supplied to the transmission circuit, and controls the gain control. And a current control means for controlling current consumption of the active circuit in accordance with a signal.

As described above, according to the high-frequency signal processing device and the transmitting / receiving device, useless power consumption can be eliminated.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a receiving apparatus according to an embodiment of the present invention. The same parts as those in the conventional example of FIG.

In FIG. 1, a digitally modulated high-frequency signal (hereinafter, RF signal), which is a downstream signal, is input from an input / output connector 1 and supplied to an RF variable attenuator 3 via a duplexer 2. The signal is input to a mixer 7 via a first RF amplifier 4, a variable-bandwidth BPF 5, and a second RF amplifier 6.

In the mixer 7, the RF signal and the signal from the local oscillator 8 are mixed and converted into an IF signal, and this IF signal is supplied to an IF gain control amplifier 11 via a first IF amplifier 9 and a BPF 10. . The output from the IF gain control amplifier 11 is output from the IF signal output terminal 13 via the second IF amplifier 12.

The IF signal output from the output terminal 13 is converted into a digital signal by an AD converter 14, and is digitally demodulated by a demodulator 15 at the next stage. The digital output from the AD converter 14 is input to the level detector 16 and supplies the output of the level detector 16 to the gain control circuit 17. The gain control circuit 17 controls the IF-AGC voltage and R
An F-AGC voltage is generated, and an IF-AGC voltage and an RF-AGC voltage are supplied to the IF gain control amplifier 11 and the RF variable attenuator 3, respectively.
Supply AGC voltage. By controlling the gains of the RF variable attenuator 3 and the IF gain control amplifier 11, control is performed so that the input level of the AD converter 14 is optimized. The operations of the RF-AGC and the IF-AGC are as shown in FIG.

On the other hand, the high frequency signal of the upstream signal is
Is supplied to the duplexer 2 via the gain control amplifier 21 and the band-pass filter 22,
And an upstream signal is transmitted to the CATV center station via a cable. The gain control amplifier 21 includes:
The intermittent control of the transmission signal and the level control of the transmission signal are performed by the control signal supplied to the terminal 23.

Further, in the present invention, a monitor control circuit 31 and a current control circuit 32 are provided. Monitor control circuit 31
Monitors the IF-AGC voltage supplied to the terminal 18,
When the IF-AGC voltage becomes equal to or higher than the reference voltage or equal to or lower than the reference voltage, a control signal is output in response thereto.
The control signal is supplied to the current control circuit 32.

The current control circuit 32 receives the control signal, controls the amount of operating current of the first RF amplifier 4, and
The current consumption of the F amplifier 4 is controlled. When the RF input signal level is high, the current consumption of the RF amplifier 4 is increased, and when the RF input signal level is low, the current consumption of the RF amplifier 4 is reduced. Perform control.

As a result, when the input level range of the downstream signal to the input / output connector 1 is near the lower limit, excessive current consumption does not flow, so that the current consumption can be suppressed.

FIG. 2 is a connection diagram showing a specific circuit example of the monitor control circuit 31 and the current control circuit 32. In FIG. 2, the monitor control circuit 31 has a differential input operational amplifier A1, and a non-inverting input terminal (+) of the operational amplifier A1 has a reference voltage V obtained by dividing the + B power supply voltage by resistors R1 and R2.
s is supplied to the inverting input terminal (−) from the terminal 18 to the IF
-AGC voltage is supplied. The current control circuit 3
2 has a field-effect transistor FET1, and controls the gate of the FET1 by the output of the operational amplifier A1.

The first RF amplifier 4 has an amplifying transistor Tr1, an RF signal is supplied to the base of the transistor Tr1 via a capacitor C1, and an amplified output is obtained from a collector via a capacitor C2. I have to. A series circuit of a load resistor RL and resistors Ra and Rb is connected between the collector of this transistor and the + B power supply, and the drain of the FET 1 is connected in parallel with the resistor Rb.
The source current path is connected.

The resistors RB1 and R2 are connected between the collector and the base of the transistor Tr1 and between the base and the ground, respectively.
B2 is connected, and a resistor RE is connected between the emitter and the ground. The connection point between the resistors RL and Ra is grounded via a capacitor Cd.

Next, the operation of FIG. 2 will be described with reference to FIG. FIG. 3 shows changes in the IF-AGC voltage (solid line a) and the RF-AGC voltage (dotted line b) with respect to the RF input level, and furthermore, the input level of the first RF amplifier 4 (solid line c).
Is shown.

In FIG. 3, when the RF input level is higher than a predetermined level (Ref1), the input of the first RF amplifier 4 is kept constant by the effect of gain reduction of the RF variable attenuator 3. At this time, the first RF
The amplifier 4 needs to set a large current consumption so as to satisfy the distortion performance. On the other hand, at this time, since the IF-AGC voltage is lower than the divided voltage VS by the resistors R1 and R2, the output of the operational amplifier A1 becomes high level,
FET1 turns on. Therefore, since the resistor Rb is bypassed, a current flows through the collector of the transistor Tr1 via the current limiting resistor (Ra + RL).

Further, the RF input level is reduced,
When the -AGC voltage becomes higher than the divided voltage VS, the output of the operational amplifier A1 becomes low level, and the FET1 is turned off.
Therefore, since the resistor Rb is connected in series to the resistors Ra and RL, a current flows through the collector of the transistor Tr1 via the current limiting resistor (Rb + Ra + RL).

That is, if the IF-AGC voltage is equal to the reference level VS
If it is lower, that is, if the input level of the first RF amplifier 4 is higher than a predetermined level, the resistance (Ra + RL)
Current flows through the transistor Tr1 and is limited by IF-
If the AGC voltage is higher than the reference level VS,
When the input level of the RF amplifier 4 is smaller than a predetermined level, a current limited by the resistor (Rb + Ra + RL) flows through the transistor Tr1.

Therefore, the current limiting resistance is (Ra + RL)
In the case of (1), the amount of current consumption is larger than in the case of the resistor (Rb + Ra + RL). Therefore, when the input level of the first RF amplifier 4 is higher than a predetermined level, the amount of current consumption is increased, and the input level is increased. When it is lower than the predetermined level, it acts to reduce the amount of current consumption. This allows
Unnecessary power consumption can be eliminated.

The switching point of the current consumption (that is, the setting of the reference voltage VS) needs to be set in consideration of the distortion performance of the first RF amplifier 4.
It is desirable to set the reference voltage VS by determining the input level Vin that does not cause a problem in the distortion performance even if the current consumption is reduced, when the input level of Vin is Vin.

In FIG. 2, the current consumption is controlled by changing the resistance value connected to the collector of the transistor Tr1, but another method of changing the bias resistance value may be used. The current control circuit 32 is a FET
Although the example using 1 has been described, a switching element such as a transistor may be used instead. Furthermore, operational amplifier A
If 1 is made to have a hysteresis characteristic, IF-
Even if the AGC voltage frequently fluctuates near the reference voltage VS, it is possible to prevent the current consumption from fluctuating carelessly.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 4, the first RF amplifier 4
In addition to providing the current control circuit 32 for the
The current control circuits 33, 34, 35 are connected to the amplifier 6, the mixer 7, and the first IF amplifier 9, respectively, and these current control circuits 32, 33, 34, 35 are connected to the monitor control circuit 3
1 is controlled.

That is, the first RF amplifier 4, the second RF amplifier 6, the mixer 7, and the first IF amplifier 9 are arranged between the input / output connector 1 and the IF gain control amplifier 11 to supply power. The active circuit is operated by a plurality of active circuits. By controlling the current consumption of the plurality of active circuits, power consumption can be further reduced.

Further, a third embodiment of the present invention will be described with reference to FIGS. FIG. 5 shows that the monitor control circuit 31 monitors the gain control signal supplied to the gain control amplifier 21 of the upstream signal, and the output of the monitor control circuit 31 controls the current control circuit 32 for the first RF amplifier 4. The current consumption of one RF amplifier 4 is controlled.

That is, the relationship between the distance on the main line from the CATV center station, the downstream signal level, and the upstream signal level is shown in FIG.
It is shown as follows. When the distance on the main line from the CATV center station is long, the output level of the upstream signal needs to be high, and conversely, the RF input level of the downstream signal decreases as the distance increases. In such a case, since the distortion performance of the RF amplifier 4 is good and the gain control signal of the upstream signal is large, the monitor control circuit 31 operates to suppress the current consumption of the RF amplifier 4.

When the distance on the main line from the CATV center station is short, the output level of the upstream signal may be low,
Conversely, the RF input level of the downstream signal increases as the distance decreases. In such a case, it is necessary to increase the current consumption of the RF amplifier 4 in order to maintain good distortion performance. However, since the gain control signal of the uplink signal becomes small, the monitor control circuit 31
Is operated so as to increase the current consumption of the RF amplifier 4.

As the gain control signal of the upstream signal, a signal represented by a voltage or a digital signal can be used. When the signal is represented by a voltage value, the operational amplifier A1 as shown in FIG. 2 can be used. In the case of (1), a comparator such as an arithmetic unit may be used to compare with the numerically set comparison setting value.

The gain control signal of the upstream signal is monitored by the monitor control circuit 31 by applying the embodiment of FIG.
The current consumption of the F amplifier 6, the mixer 7, and the first IF amplifier 9 may also be controlled, so that the power consumption can be further reduced.

[0047]

As described above, according to the present invention, it is possible to suppress the power consumption in the receiving device and the transmitting / receiving device while keeping the distortion performance of the active circuit in the receiving device at an optimum.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a high-frequency signal processing device according to an embodiment of the present invention.

FIG. 2 is a connection diagram illustrating a configuration of a monitor control circuit and a current control circuit used in the present invention.

FIG. 3 is a characteristic diagram for explaining the operation of the present invention.

FIG. 4 is a block diagram showing a high-frequency signal processing device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a transmitting / receiving apparatus according to a third embodiment of the present invention.

FIG. 6 is a characteristic diagram for explaining the operation of FIG. 5;

FIG. 7 is a block diagram showing a conventional transmitting / receiving apparatus.

FIG. 8 is a characteristic diagram for explaining a gain control operation of the conventional receiving apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Connector for input / output 2 ... Divider 3 ... RF variable attenuator 4 ... 1st RF amplifier 6 ... 2nd RF amplifier 7 ... Mixer 8 ... Local oscillator 9 ... 1st IF amplifier 11 ... IF gain Control amplifier 12 second IF amplifier 17 AGC voltage generation circuit 21 upstream signal gain control amplifier 31 monitor control circuit 32, 33, 34, 35 current control circuit 100 reception circuit 200 transmission circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 1/26 H04B 1/26 H 5K011 1/40 1/40 5K020 H04N 7/173 630 H04N 7/173 630 5K062 F term (reference) 5C026 BA18 5C064 BA01 BB10 BC20 BC27 5J069 AA01 AA51 AA55 BC03 CA36 CA81 FA04 FA10 FA17 FA18 HA02 HA09 HA18 HA25 HA29 HA39 KA02 KA12 KA17 KA47 KA49 KA55 MA08 A09 MA01 A08 A08 FA10 FA17 FA18 GR06 GR09 HA02 HA09 HA18 HA25 HA29 HA39 KA02 KA12 KA17 KA47 KA49 KA55 MA08 MA11 MA20 MA21 SA08 TA01 TA02 5J100 JA01 KA05 LA09 LA10 LA11 QA01 QA02 QA03 SA03 5K011 DA03 DA13 FA07 FA09 GA03 DD03 JA03 DD03 EE04 LL01 5K062 AB14 AD04 AD05 AD07 AD09 AG01 BC03 BD02 BE08

Claims (9)

[Claims] An input terminal to which a high-frequency signal is input, a circuit for receiving a first high-frequency signal supplied to the input terminal and converting the signal into an intermediate frequency, and a gain control signal for controlling the gain of the intermediate frequency signal A receiving circuit including a plurality of active circuits between the input terminal and the gain control circuit, wherein the receiving circuit includes a plurality of active circuits, and detects the gain control signal supplied to the gain control circuit; Current control means for controlling current consumption of the active circuit in accordance with a gain control signal. 2. The active circuit includes a high-frequency amplifier for amplifying the first high-frequency signal, a mixer for converting the first high-frequency signal to an intermediate frequency, and an intermediate for amplifying an output signal from the mixer. 2. The high-frequency signal processing device according to claim 1, further comprising a high-frequency amplifier, wherein the current control means controls current consumption of at least one circuit of the high-frequency amplifier, the mixer, and the intermediate-frequency amplifier. . 3. The gain control signal is an IF-AGC voltage that changes according to an input level of the first high-frequency signal, and the current control unit controls the IF-AGC voltage and a predetermined reference voltage. A comparison circuit that generates a comparison output that changes when an input level of the first high-frequency signal becomes lower than a predetermined level; and an input level of the first high-frequency signal in response to a comparison result of the comparison circuit. 2. The high-frequency signal processing device according to claim 1, further comprising a current control circuit configured to reduce a current consumption of the active circuit when the voltage is smaller than a predetermined level. 4. The current control circuit includes an amplifying transistor to which a signal is supplied between a base and an emitter, and a plurality of resistor series circuits connected between a collector of the transistor and a voltage source. The means comprises a switching element connected in parallel with one of the resistors in the resistor series circuit, and switches the switching element in response to a comparison result of the comparison circuit. The transmission / reception device according to claim 3. 5. An input / output terminal for inputting / outputting a high-frequency signal, a circuit for receiving the first high-frequency signal supplied to the input / output terminal and converting it to an intermediate frequency, and controlling a gain of the intermediate frequency signal. A reception circuit including a plurality of active circuits between the input / output terminal and the gain control circuit; an input terminal to which a second high-frequency signal for transmission is supplied; A control terminal to which a gain control signal for controlling the gain of the second high-frequency signal is supplied, and a second high-frequency signal supplied to the input terminal is controlled by the gain control signal and supplied to the input / output terminal A transmission circuit, detecting the gain control signal supplied to the transmission circuit,
A transmission / reception device comprising: current control means for controlling current consumption of the active circuit according to the gain control signal. 6. The current control means controls in response to the gain control signal to reduce current consumption of the active circuit when an input level of the first high-frequency signal is lower than a predetermined level. The transmission / reception device according to claim 5, characterized in that: 7. The active circuit includes a high-frequency amplifier for amplifying the first high-frequency signal, a mixer for converting the first high-frequency signal to an intermediate frequency, and an intermediate for amplifying an output signal from the mixer. 6. The transmission / reception device according to claim 5, further comprising a frequency amplifier, wherein the current consumption of at least one circuit of the high frequency amplifier, the mixer, and the intermediate frequency amplifier is controlled by the current control means. 8. The transmission / reception apparatus according to claim 7, wherein the current consumption of said high-frequency amplifier in said active circuit is controlled by said current control circuit. 9. An input / output terminal for inputting / outputting a high-frequency signal, a circuit for receiving the first high-frequency signal supplied to the input / output terminal and converting it to an intermediate frequency, and controlling a gain of the intermediate frequency signal And a first gain control circuit for outputting the first gain control circuit between the input / output terminal and the first gain control circuit.
A receiving circuit including a high-frequency amplifier for amplifying the high-frequency signal, a mixer for converting the first high-frequency signal to an intermediate frequency, and an intermediate-frequency amplifier for amplifying an output signal from the mixer; And a control terminal to which a gain control signal for controlling the gain of the second high-frequency signal is supplied, wherein the second high-frequency signal supplied to the input terminal is supplied to the input terminal. A transmission circuit controlled by a control signal and supplied to the input / output terminal, and detecting the gain control signal supplied to the transmission circuit,
In response to the gain control signal, current consumption of at least one of the high-frequency amplifier, the mixer, and the intermediate-frequency amplifier of the receiving circuit is reduced when the input level of the first high-frequency signal is lower than a predetermined level. And a current control means for controlling the transmission and reception.