JP3315948B2 - Radio apparatus and gain control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio apparatus used for a transmitter / receiver of a mobile communication system and a method of controlling the gain thereof, and more particularly, to enabling fine control of the gain of an RF stage. .

[0002]

2. Description of the Related Art For example, in a radio device used for a receiver, it is required that the reception quality does not deteriorate even when an interfering wave is mixed. Therefore, when the received signal level is high and the interference wave level is also high, the received signal level is attenuated by lowering the gain of the RF stage,
The level of the interfering wave is attenuated to prevent saturation of the circuit constituting the receiver.

As shown in FIG. 7, such a conventional radio apparatus includes an antenna 31 for transmitting and receiving radio signals, and an antenna 31 for transmitting and receiving radio signals.
A duplexer 32 for sharing 31 for transmission and reception, a low-noise amplifier 33 for amplifying a received signal, an attenuator 34 located in front of the low-noise amplifier 33 for attenuating a received signal, and operating the attenuator 34 A switch 35 for selecting whether or not an RF band-pass filter 36 for limiting the band of the amplified received signal;
A mixer 37 for converting the received signal passed through the band-pass filter 36 into an IF signal, a first Lo oscillator 38 for outputting a Lo signal to the mixer 37, and an IF filter 39 for removing unnecessary components from the output of the mixer 37; A variable gain IF amplifier 40 for adjusting the IF signal level, and a second Lo oscillator 41 for outputting a Lo signal for converting the IF signal into I and Q signals.
And a quadrature demodulator 42 for performing quadrature detection based on the Lo signal output from the second Lo oscillator 41, a baseband filter 43 for removing unnecessary components of the demodulated I and Q outputs, and detecting the intensity of the I and Q demodulated signals. A signal strength detector 44, and a signal strength determiner 45 for controlling the ON / OFF of the switch 35 and the gain of the variable gain IF amplifier 40 based on the detected signal strength.

Next, the operation of the radio apparatus shown in FIG. 7 will be described.

A signal transmitted from a radio base station passes through an antenna 31 and a duplexer 32 and is amplified by a low noise amplifier 33. Subsequently, after passing through the RF bandpass filter 36,
The signal is converted by the mixer 37 into an IF signal. Further, after passing through an IF filter 39, the level is adjusted by a variable gain IF amplifier 40, and is converted into I and Q demodulated signals by a quadrature demodulator 42. The I and Q demodulated signals pass through a baseband filter 43, and a received signal strength is detected by a signal strength detector 44. The signal strength detection result is input to a signal strength determiner 45, and when it is determined that the signal strength has exceeded a certain threshold level, the attenuator 34 in front of the low noise amplifier 33 is operated, and the RF Switch the amount of attenuation.

However, the radio apparatus shown in FIG.
Only two stages of switching of the attenuation of the RF stage for the received signal are possible. For this reason, the attenuation of the RF stage with respect to the received signal can not be finely controlled in accordance with the received signal strength, and the influence of the interfering wave cannot be appropriately suppressed.

To cope with this problem, Japanese Patent Laid-Open No. 10-2
No. 8066 discloses a switch for selecting / non-selecting an operation of the attenuator 34 located at a preceding stage of the low noise amplifier 33 in FIG. A new signal strength detector 45
Discloses that the switching control of these two switches is performed in accordance with the received signal strength, and the amount of attenuation of the RF stage for the received signal is switched in multiple stages.

[0008]

However, in the system in which the switching of the amount of attenuation of the RF stage with respect to the received signal is controlled in a stepwise manner, the received signal strength becomes close to the threshold level which is the determination level of the signal strength determiner 45. If the received signal strength decreases, there is a problem that switch switching frequently occurs.To avoid this, the signal strength determination unit 45 is provided with a hysteresis characteristic, and a threshold level for performing switch switching when the received signal strength is reduced. In addition, there is a problem that it is necessary to make a difference from a threshold level at which a switch is switched when the received signal strength increases, and the determination operation becomes complicated.

Further, CDMA (Code Division Multip
le Access) requires a gain control characteristic with excellent linearity of about 80 dB for a variable gain IF amplifier. The gain is set. on the other hand,
Since the attenuation of the RF stage is set by multi-stage switching control, the gain of the variable gain IF amplifier and the gain of the RF stage are separately set so that the entire wireless device has a linear gain control characteristic. However, there is a problem that the gain control is complicated.

The present invention solves such a conventional problem. The present invention continuously controls the attenuation of an RF stage with respect to a received signal, has a linear gain control characteristic as a whole of the apparatus, and reduces the received signal strength. Accordingly, it is an object of the present invention to provide a radio apparatus capable of appropriately controlling the amount of attenuation of an RF stage with respect to a received signal to appropriately suppress the influence of an interference wave, and to provide a method of controlling the gain thereof.

[0011]

Therefore, in the wireless device of the present invention, a variable gain function is provided in the low noise amplifier so that the gain is set by continuous control.

[0012] Therefore, the hysteresis characteristic at the time of signal intensity determination becomes unnecessary, also to match the linear gain control characteristic of the variable gain IF amplifier, it is possible to gain control characteristic of the entire radio system linearly, the reception In accordance with the signal strength, the amount of attenuation in the RF stage with respect to the received signal is finely controlled, so that the influence of the interfering wave can be appropriately suppressed.

Further, according to the gain control method of the present invention, each of the variable gain low noise amplifier and the variable gain IF amplifier includes:
With a linear gain control characteristic in a predetermined gain control range,
The gain control characteristic of the variable gain low noise amplifier and the gain control characteristic of the variable gain IF amplifier are linearly connected to the gain control voltage, and the gain of the variable gain low noise amplifier and the gain of the variable gain IF amplifier are configured. Is controlled separately.

Therefore, the gain control of the IF stage can be started after the gain control of the RF stage is completed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a variable gain low noise amplifier for adjusting the amount of amplification for a received signal, a mixer for converting a received signal to an IF signal, and a converted IF signal. A variable gain IF amplifier for adjusting the level, a signal strength detector for detecting the signal strength of the received signal,
Based on the detected signal strength, provided a signal strength determiner for adjusting the variable gain low noise amplifier and variable gain IF amplifier gain, the variable gain low noise amplifier and variable gain I
Each of the F amplifiers is linear over a given gain control range
The gain control characteristics of the variable gain low noise amplifier
Gain control characteristics and gain control characteristics of the variable gain IF amplifier
The entire wireless device has a linear gain control characteristic.
Since the RF stage attenuation is controlled by a variable gain low noise amplifier, the RF stage attenuation for the received signal is finely controlled according to the received signal strength, and the interference wave Can be appropriately suppressed.
In addition, the hysteresis characteristics in the signal strength determiner become unnecessary. Also, a variable gain low noise amplifier and a variable gain IF amplifier
Gain control in the same manner,
The gain of the stage and the gain of the IF stage can be controlled separately.
You.

[0016]

[0017]

According to a second aspect of the present invention, there is provided a variable gain low noise amplifier for adjusting the amount of amplification with respect to a received signal, a mixer for converting the received signal into an IF signal, and a variable gain IF for adjusting the level of the converted IF signal. An amplifier and a variable gain low noise amplifier for a wireless device including a signal strength detector for detecting a signal strength of a received signal and a control method for controlling the gain of a variable gain IF amplifier based on the received signal strength. Each of the amplifier and the variable gain IF amplifier has a linear gain control characteristic in a predetermined gain control range, and the gain control characteristic of the variable gain low noise amplifier and the variable gain I
The gain control characteristic of the F-amplifier is configured so as to be linearly connected to the gain control voltage, and the gain of the variable-gain low-noise amplifier and the gain of the variable-gain IF amplifier are controlled separately. , After the gain control of the RF stage is completed,
A control method that starts the gain control of the F stage becomes possible.

According to a third aspect of the present invention, the wireless device according to the first aspect is used for a portable terminal, and a high-performance portable terminal can be realized.

According to a fourth aspect of the present invention, there is provided a communication system using the portable terminal according to the third aspect , and a high-performance communication system can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 shows a wireless device according to a first embodiment of the present invention. This device is
An antenna 1 for transmitting and receiving a radio signal, a duplexer 2 for sharing the antenna 1 for transmission and reception, a variable gain low noise amplifier 3 for amplifying a received signal, and an RF bandpass filter for limiting a band of the amplified received signal 6, a mixer 7 for converting a received signal passed through the RF bandpass filter 6 into an IF signal, a first Lo oscillator 8 for outputting a Lo signal to the mixer 7, and an IF filter 9 for removing unnecessary components from the output of the mixer 7 A variable gain IF amplifier 10 for adjusting the level of the converted IF signal; a second Lo oscillator 11 for outputting a Lo signal for converting the IF signal into I and Q signals;
a quadrature demodulator 12 for performing quadrature detection based on the Lo signal output from the o-oscillator 11, a baseband filter 13 for removing unnecessary components of the demodulated I and Q outputs, and a signal strength for detecting the strength of the I and Q demodulated signals. A detector 14 and a signal strength determiner 15 for controlling the gains of the variable gain low noise amplifier 3 and the variable gain IF amplifier 10 based on the detected signal strength are provided.

FIG. 8 shows a specific example of the variable gain circuit constituting the variable gain IF amplifier 10.

This variable gain circuit includes transistors 101 and 102 whose emitters are connected to each other via a resistor 183;
It has transistors 111 and 112 whose emitters are connected to each other via a resistor 193, and an input voltage Vid is applied to each base (Vin terminal) of the transistors 101 and 111 and each base (Vinx terminal) of the transistors 102 and 112. ). The respective emitters of the connected transistors 101 and 102 are grounded via voltage controlled current sources 181 and 182, and the respective emitters of transistors 111 and 112 are grounded via voltage controlled current sources 191 and 192. . Transistor 10
Each collector (Voutx terminal) of 1 and 111 is connected to a power supply via a resistor 171, and each collector (Vout terminal) of the transistors 102 and 112 is connected to a power supply via a resistor 172. Also, the voltage controlled current sources 181, 182, 191, 192 are:
The transistor 11 is controlled by the gain control voltage Vcd.
An output voltage Vod is output between the collectors 1 and 112.

Next, the operation of the circuit shown in FIG. 8 will be described.

An input voltage Vid is applied to a transistor
The collector current of 101 becomes + ΔI1, and the transistor 102
Is -ΔI1. Where ΔI
1 is represented by (Equation 1), where the resistance value of the resistor 183 is RE1. ΔI1 = Vid / (2VT / I1 + RE1) (1) Here, I1 is each current value of the voltage control current sources 181 and 182, VT is a thermal voltage, and VT is (Formula 2) Given by VT = kT / q (2) where k is Boltzmann's constant, T is absolute temperature, and q is the amount of charge.

Similarly, it is assumed that the input voltage Vid is applied, the collector current of the transistor 111 becomes + ΔI2, and the collector current of the transistor 112 becomes -ΔI2. Here, ΔI2 is given assuming that the resistance value of the resistor 193 is RE2.
It is represented by (Equation 3). ΔI2 = Vid / (2VT / I2 + RE2) (Equation 3) Here, I2 is each current value of the voltage control current sources 191 and 192, and VT is a thermal voltage.

Therefore, the output voltage Vod is supplied to the resistors 171 and 172 by (ΔI1 + ΔI2) and − (ΔI1 + ΔI2), respectively.
Therefore, when each resistance value of the resistors 171 and 172 is RL, it is expressed by (Equation 4). Vod = 2RL (ΔI1 + ΔI2) (Expression 4) By substituting (Expression 1) and (Expression 3) into (Expression 4), (Expression 5) representing the gain G (= Vod / Vid) is obtained. Can be G = RL (gm1 + gm2) (Equation 5) where gm1 and gm2 are (Equation 6) and (Equation 7), respectively.
Given by gm1 = 1 / (VT / I1 + RE1 / 2) (Equation 6) gm2 = 1 / (VT / I2 + RE2 / 2) (Equation 7) According to (Equation 6) and (Equation 7) Since the contained current values of I1 and I2 are controlled by the gain control voltage Vcd, g
m1 and gm2 also change accordingly. Therefore, the gain G represented by (Equation 5) can be changed with respect to the gain control voltage Vcd.

FIG. 9 shows voltage controlled current sources 181, 182, 191, 1
92 shows a circuit example.

This circuit has transistors 73 and 74, and a control voltage Vcd is input between the bases of the transistors 73 and 74. The respective emitters of the transistors 73 and 74 are connected, and are connected to a power supply via a current source 75. The collector of the transistor 73 is connected to the input terminal IN of the current mirror circuit 71 having a mirror ratio of 1: α, and the collector of the transistor 74 is connected to the input terminal IN of the current mirror circuit 72 having a mirror ratio of 1: β. Have been. The current I1 is output from the output terminal OUT of the current mirror circuit 71, and the current I2 is output from the output terminal OUT of the current mirror circuit 72.

Next, the operation of the circuit shown in FIG. 9 will be described.

Suppose that gain control voltage Vcd is applied, the collector current of transistor 73 becomes I73, and the collector current of transistor 74 becomes I74. I73 and I74 are represented by (Equation 8) and (Equation 9). I73 = M · I0 / (1 + M) (Equation 8) I74 = I0 / (1 + M) (Equation 9) Here, M is represented by (Equation 10). M = exp (Vcd / VT) (Equation 10)

From equation (8), the current I1 output from the output terminal OUT of the current mirror circuit 71 is expressed by equation (11). I1 = α · M · I0 / (1 + M) (11)

Similarly, from equation (9), the current I2 output from the output terminal OUT of the current mirror circuit 72 is
It is represented by (Equation 12). I2 = β · I0 / (1 + M) (12)

Now, let RE1 << RE2, α >> β.
In the case of Vcd >> 0, M converges to infinity from (Expression 10), the value of I1 becomes α · I0 from (Expression 11), and the value of I2 becomes zero from (Expression 12). Therefore, the values of gm1 and gm2 are obtained from (Equation 6) and (Equation 7), and (Equation 5)
, The maximum gain Gmax is obtained, and (Equation 1)
It is represented by 3). Gmax = 2RL / {VT / (α · I0) + RE1 / 2} (Expression 13)

Similarly, when Vcd << 0, (Equation 1)
From (0), M converges to zero, from (Equation 11), the value of I1 becomes zero, and from (Equation 12), the value of I2 becomes β · I0.
Therefore, from (Equation 6) and (Equation 7), gm1 and gm2
Is obtained and substituted into (Equation 5), the minimum gain Gmi
n is obtained and expressed by (Equation 14). Gmin = 2RL / {VT / (β · I0) + RE2 / 2} (Equation 14)

Therefore, the gain G can be changed by the gain control voltage Vcd, and a variable gain circuit can be configured.

As described above, a variable gain IF amplifier used in a communication system represented by CDMA is required to have a gain control characteristic excellent in linearity of about 80 dB. Therefore, the variable gain circuits shown in FIG. 8 are continuously connected to a plurality of stages, an offset voltage is applied to the gain control voltages of the variable gain circuits of each stage, and the gain control widths of the variable gain circuits of each stage are appropriately overlapped. Thus, a gain control characteristic having a wider gain control width and excellent linearity can be obtained.

By the way, in this variable gain circuit,
For example, if α: β = 3: 1, the current consumption at the minimum gain can be reduced to １ ／ of that at the maximum gain. Therefore, when the variable gain circuits are continuously connected in a plurality of stages, there is a remarkable effect that the current consumption at the minimum gain can be reduced with respect to the current consumption at the maximum gain.

However, since the variable gain circuit of FIG. 8 has a differential configuration and is not suitable for reducing noise, it is difficult to configure a variable gain low noise amplifier.

FIG. 2 shows a specific example of a variable gain low noise amplifier having the same variable gain function as the variable gain circuit of FIG.

This amplifier includes transistors 21 and 22 to which an input voltage Vi is input to each base (Vin terminal). The emitters of the transistors 21 and 22 are grounded via voltage controlled current sources 23 and 25. A capacitor 24 is connected in parallel to the voltage control current source 23, and a resistor 26 and a capacitor 27 connected in series are connected to the voltage control current source 25 in parallel. Each collector (Vout terminal) of the transistors 21 and 22 is connected to a power supply via a resistor 28. The voltage control current sources 23 and 25 are controlled by the gain control voltage Vcd, and the output voltage Vo is output from the collectors of the transistors 21 and 22.

Next, the operation of the circuit shown in FIG. 2 will be described.

The input voltage Vi is applied, and the transistor 21
Is assumed to be + ΔI1, and the impedance of the capacitor 24 is set to be negligible in the frequency band used in the circuit of FIG. Where Δ
I1 is represented by (Equation 15). ΔI1 = Vi / (VT / I1) (Equation 15) Here, I1 is a current value of the voltage control current source 23, and VT
Is the thermal voltage.

Similarly, it is assumed that the input voltage Vi is applied, the collector current of the transistor 22 becomes + ΔI2, and the impedance of the capacitor 27 is set to be negligible in the frequency band used in the circuit of FIG. Here, ΔI2 is given assuming that the resistance value of the resistor 26 is RE / 2.
It is represented by (Equation 16). ΔI2 = Vi / (VT / I2 + RE / 2) (16)

Here, I2 is a current value of the voltage control current source 25, and VT is a thermal voltage.

Therefore, the output voltage Vo is applied to the resistor 28 by (ΔI
1 + ΔI2), the resistance of the resistor 28 is changed to R
If L, it is represented by (Equation 17). Vo = RL (ΔI1 + ΔI2) (Equation 17) By substituting (Equation 15) and (Equation 16) into (Equation 17), (Equation 18) representing the gain G (= Vo / Vi) is obtained. Can be G = RL (gm1 + gm2) (Equation 18) where gm1 and gm2 are (Equation 19) and (Equation 2), respectively.
0). gm1 = 1 / (VT / I1) (Equation 19) gm2 = 1 / (VT / I2 + RE / 2) (Equation 20)

Since the current values of I1 and I2 included in (Equation 19) and (Equation 20) are controlled by the gain control voltage Vcd, gm1 and gm2 also change accordingly.
Therefore, the gain G expressed by (Equation 18) is changed to the gain control voltage Vc.
d, and it can be understood that the gain control of the variable gain low noise amplifier 3 and the variable gain IF amplifier 10 is based on the same operation principle.

Next, a method of controlling the variable gain low noise amplifier 3 and the variable gain IF amplifier 10 will be described. here,
The variable gain low noise amplifier 3 is constituted by one stage of the circuit of FIG.
The variable gain IF amplifier 10 is configured by continuously connecting the circuits of FIG. 8 in five stages, and an example in which the gain control width of one stage of the circuits of FIGS. 2 and 8 is set to the same (20 dB) will be described. I do.

Since the gain control of the circuits shown in FIGS. 2 and 8 is based on the same operation principle, an offset voltage is applied to the gain control voltages of the respective stages as shown in FIG. By combining, for a gain control width of 100 dB,
It is possible to obtain gain control characteristics with excellent linearity. In the example shown in FIG. 3, the gain control voltage range is such that the RF stage has a gain control width of 20 dB and the IF stage has a gain control width of 80 dB.

As described above, in this radio apparatus, since the low noise amplifier is provided with the variable gain function in the same manner as the variable gain IF amplifier, the gain is controlled by the same control method as the variable gain IF amplifier. It can be controlled continuously. Therefore, the amount of attenuation of the RF signal with respect to the received signal is finely controlled according to the received signal strength, so that the influence of the interfering wave can be appropriately suppressed. Further, the hysteresis characteristic at the time of determining the signal strength becomes unnecessary.

(Second Embodiment) In a radio apparatus according to a second embodiment of the present invention, the entire apparatus is linear by combining the linear gain control characteristics of the variable gain low noise amplifier 3 and the variable gain IF amplifier 10. It is configured to have gain control characteristics.

Here, the variable gain low noise amplifier 3 corresponds to FIG.
8 is continuously connected, and the variable gain IF amplifier 10 is formed by continuously connecting the circuit of FIG.
2 and 8 have the same gain control width (20d
The case where B) is set will be described as an example.

As shown in FIG. 4, the variable gain low noise amplifier 3 applies an offset voltage to the gain control voltage of each stage,
By appropriately overlapping the gain control width of each stage, 20d
With respect to the gain control width of B, it is possible to obtain a gain control characteristic excellent in linearity.

On the other hand, in the variable gain IF amplifier 10, as shown in FIG. 5, an offset voltage is applied to the gain control voltages of the respective stages, and the gain control widths of the respective stages are appropriately overlapped with each other.
It is possible to obtain a gain control characteristic excellent in linearity for a gain control width of 0 dB.

As described above, when the variable gain low noise amplifier 3 and the variable gain IF amplifier 10 have high linearity in the required gain control range, each gain control characteristic is controlled as shown in FIG. Since it can be configured to be connected linearly to the voltage, the gain of the RF stage and the IF
The gain of the stage can be controlled separately. At this time, it is necessary to stop the gain control of the RF stage and the IF stage at the connection point.

According to this method, when the gain of the RF stage is controlled, the gain of the IF stage is not simultaneously controlled, and the gain control of the IF stage is started after the gain control of the RF stage is completed. Can be dealt with when it is necessary to control

By using such a wireless device for a portable terminal, the performance of the portable terminal can be improved, and a high-performance communication system can be constructed.

[0059]

As is clear from the above description, in the radio apparatus and the gain control method of the present invention, the variable gain function is provided in the low noise amplifier so that the gain can be set by continuous control. In addition, the hysteresis characteristic in the signal strength determiner becomes unnecessary. Further, by performing control in combination with the variable gain IF amplifier, the gain control characteristic of the entire wireless device can be provided with high linearity, and the attenuation of the RF stage with respect to the received signal can be finely adjusted according to the received signal strength. Control
The effect of the interfering wave can be appropriately suppressed.

The variable gain low noise amplifier and the variable gain IF amplifier are provided with high linearity in the required gain control range, and the gain control characteristics of the variable gain low noise amplifier and the variable gain IF amplifier are increased. By being configured to be linearly connected to the control voltage, the gain of the RF stage and the gain of the IF stage can be controlled separately.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a wireless device according to first and second embodiments of the present invention;

FIG. 2 is a circuit diagram of a variable gain low noise amplifier according to the first and second embodiments of the present invention,

FIG. 3 shows a gain control characteristic of the wireless device according to the first embodiment of the present invention;

FIG. 4 shows a gain control characteristic of a variable gain low noise amplifier according to a second embodiment of the present invention;

FIG. 5 shows a variable gain IF according to a second embodiment of the present invention.
Amplifier gain control characteristics,

FIG. 6 illustrates a gain control characteristic of a wireless device according to a second embodiment of the present invention;

FIG. 7 is a block diagram illustrating a configuration of a conventional wireless device.

FIG. 8 is a circuit diagram of a variable gain circuit constituting the variable gain IF amplifier;

FIG. 9 is a circuit diagram of a voltage controlled current source.

[Explanation of symbols]

 1, 31 antenna 2, 32 duplexer 3 variable gain low noise amplifier 6, 36 RF bandpass filter 7, 37 mixer 8, 38 first Lo oscillator 9, 39 IF bandpass filter 10, 40 variable gain IF amplifier 11, 41 2Lo oscillator 12,42 Quadrature detector 13,43 Baseband filter 14,44 Signal strength detector 15,45 Signal strength determiner 21,22,73,74,101,102,111,112 Transistor 23,25,181, 182, 191, 192 Voltage controlled current source 24, 27 Capacitor 26, 28, 171, 172, 183, 193 Resistance 33 Low noise amplifier 34 Attenuator 35 Switch 71, 72 2-output current mirror circuit 75 Current source

Claims (4)

(57) [Claims] 1. A variable gain low noise amplifier for adjusting an amount of amplification of a received signal, a mixer for converting a received signal into an IF signal, a variable gain IF amplifier for adjusting a level of the converted IF signal, and a signal of the received signal. comprising a signal strength detector for detecting the intensity, based on the signal intensity detected by the signal intensity detector, and a signal strength determiner for adjusting the gain of the variable gain low noise amplifier and variable gain IF amplifier,
The variable gain low noise amplifier and the variable gain IF amplifier
Each has a linear gain control characteristic within a predetermined gain control range.
And the gain control characteristics of the variable gain low noise amplifier.
And the gain control characteristics of the variable gain IF amplifier,
A wireless device, wherein the entire wireless device has a linear gain control characteristic . 2. A variable for adjusting the amount of amplification with respect to a received signal.
Gain low-noise amplifier and a
Mixer and variable gain to adjust the converted IF signal level
IF amplifier and signal strength for detecting signal strength of received signal
The variable gain low noise amplifier of a wireless device comprising a detector
And the gain of the variable gain IF amplifier based on the received signal strength
A variable gain low noise amplifier and a variable gain IF amplifier.
In each case, the linear gain control characteristics in the predetermined gain control range
The gain control characteristics of the variable gain low noise amplifier and
The gain control characteristic of the variable gain IF amplifier is
Pressure linearly connected to the
Gain of the low-noise amplifier and gain of the variable gain IF amplifier
And a gain control method. 3. A portable device using the wireless device according to claim 1.
Terminal. 4. Communication using the portable terminal according to claim 3.
system.