JP3231973B2 - Bias change circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias changing circuit provided in a radio receiving system such as a portable telephone for changing an amplification characteristic with respect to a received signal.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a configuration of a conventional portable telephone and a booster. Conventionally, when using a portable telephone or the like small-output as an in-vehicle phone high output, the mobile phone or the like, is connected to an external device, commonly referred to as a booth data. The booster 30 connected to the mobile phone 10
It has a function of amplifying a transmission / reception signal for the mobile phone 10. The mobile phone 10 has a transmitting / receiving antenna 11
, And the booster 30 also includes an antenna 31 for transmission and reception. The input / output node N of the mobile phone 10 is provided with a switch, and when transmission and reception are performed by the mobile phone alone,
When the antenna 11 is connected to the node N and the operation is performed via the booster 30, the node N is connected to the booster 30. The mobile phone 10 includes a receiving unit 10A and a transmitting unit 10B. Node N is the receiving unit 10A
And the transmitting unit 10B, and the receiving unit 10A and the transmitting unit 10
B is connected to a control unit 10C that performs control and voice processing in the mobile phone 10. The receiving unit 10A includes a band-pass filter 12 connected to the node N, and a first-stage amplifier 13 is connected to an output side of the band-pass filter 12. An amplifier 14 is further connected to an output side of the amplifier 13, and a band-pass filter 15 is connected to an output side of the amplifier 14. Bandpass filter 1
The output of 5 is connected to the mixer 16. Mixer 16
Is the output signal of the band-pass filter 15 and the local oscillator 1
The demodulator 18 is connected to the output side of the mixer 16. The output side of the demodulator 18 is connected to the control unit 10C.

The transmitting section 10B includes a modulator 19 for modulating a signal from the control section 10C. The output side of the modulator 19 is connected to the mixer 20. The mixer 20 includes the modulator 1
The output signal of the mixer 9 is multiplied by the frequency signal from the local oscillator 17. A band pass filter 21 is connected to the output side of the mixer 20. An amplifier 22 is connected to an output side of the bandpass filter 21, and an output side of the amplifier 22 is connected to a bandpass filter 23. An amplifier 24 is connected to the output side of the bandpass filter 23, and the output side of the amplifier 24 is connected to the node N via the bandpass filter 25. The mobile phone 10 is configured to be capable of transmitting and receiving without using the booster 30, and realizes a low noise figure and a low distortion characteristic by itself. That is, the first-stage amplifier 13 in the receiving unit 10A is designed to have a low noise figure characteristic with respect to a given bias, and the second-stage amplifier 14 and the mixer 16 have low distortion and high saturation output characteristics. It is designed to have. When the mobile telephone 10 is connected to the booth motor 3 0, transmission and receiving are performed through the booster 30.

[0004]

However, the conventional mobile phone 10 has the following problems. When used as an in-vehicle phone, the mobile phone 10
, And the signal amplified by the booster 30 is already input to the first-stage amplifier 13 of the receiving unit 10A. In this state, the amplifier 13 functions as a subsequent-stage amplifier. However, since the distortion characteristics are not optimized, a problem occurs that the cross-modulation characteristics of the mobile phone 10 deteriorate. In order to prevent deterioration of the cross-modulation characteristics, it is conceivable to make the amplifier 13 compatible with low distortion, low noise figure and high saturation output characteristics, or to change the design to one having a moderate characteristic. However, if these measures are taken, it becomes an obstacle to reducing the power consumption of the mobile phone 10 and optimizing the reception performance.

[0005]

Means for Solving the Problems The present invention, in order to solve the above problems, in the bias changing circuit, the communication device having an amplification element with an amplification characteristic based on a given bias to amplify the received signal Amplifying the received signal provided
External device for inputting to the amplifying element
The connection status when connected to the machine, and has a function of giving to the amplifying device by changing the bias.

[0006]

According to the present invention, since the configuration of the bias changing circuit as described above, in the case where communication device such as a mobile phone is used alone and when connected to an external device, different bias Give to the amplifying element. Therefore, the low distortion, low noise figure, and high saturation output characteristics of the amplification element change in accordance with the bias. Therefore, the above problem can be solved.

[0007]

FIG. 1 is a block diagram showing a configuration of a portable telephone and a booster according to an embodiment of the present invention. Elements common to those in FIG. 2 are denoted by the same reference numerals. Booster 30
Has a function of amplifying a transmission / reception signal for a connected communication device, and has a transmission / reception antenna 31 similarly to FIG. The antenna 31 is commonly connected to a booster receiving unit 32 and a booster transmitting unit 33 inside the booster 30. The mobile phone 40 as a communication device includes a dedicated transmitting / receiving antenna 41. The input / output node N1 of the mobile phone 40 is provided with a switch 42. When transmission / reception is performed by the mobile phone alone, the antenna 41 is connected to the node N1, and when transmission / reception is performed via the booster 30 which is an external device, the node N1 is connected. Are connected to the booster receiving unit 32 and the booster transmitting unit 33. A receiving section 40A and a transmitting section 40B are provided inside the mobile phone 40. The node N1 is connected to a receiving unit 40A and a transmitting unit 40B, and the receiving unit 40A and the transmitting unit 40B are connected to a control unit 40C that controls the inside of the mobile phone 40 and performs voice processing and the like. The cellular phone 40 of Figure 1, and the newly booster detecting circuit 60 and the bias change circuit 70 is provided. The booster detection circuit 60 has a function of notifying the control unit 40C that the booster 30 has been connected. Further, the bias changing circuit 70 has a function of changing the bias applied to the receiving unit 40A under the control of the control unit 40C . The output side of the booster detection circuit 60 is connected to the control unit 40C, the bias changing circuit 70 is connected to the control unit 40 C. Receiver 40
A is a band-pass filter 43 connected to the node N1.
The first-stage amplifier 44 is connected to the output side of the band-pass filter 43. An amplifier 45 is further connected to an output side of the amplifier 44, and a band-pass filter 46 is connected to an output side of the amplifier 45. The output side of the band pass filter 46 is connected to the mixer 47. The mixer 47 multiplies an output signal of the band-pass filter 46 by a frequency signal from the local oscillator 48, and a demodulator 49 is connected to an output side of the mixer 47. The output side of the demodulator 49 is connected to the control unit 40C.

The transmitting section 40B includes a modulator 50 for modulating data from the control section 40C, and the output side of the modulator 50 is connected to the mixer 51. The mixer 51 multiplies the output signal of the modulator 50 by the frequency signal from the local oscillator 48, and a band-pass filter 52 is connected to the output side of the mixer 51. An amplifier 53 is connected to an output side of the band-pass filter 52, and an output side of the amplifier 53 is connected to a band-pass filter 54. An amplifier 55 is connected to the output side of the bandpass filter 54, and the output side of the amplifier 55 is connected to the node N1 via the bandpass filter 56. FIG. 3 is a circuit diagram showing an example of the bias changing circuit 70 and the amplifier 44 in FIG . For example, amplifier 44
Includes a coupling capacitor 44 ₁ provided between the previous stage of the bandpass filter 43. Capacitor 44 ₁
Output side of, and is connected to the base of npn transistor 44 _{and second} amplifying elements. The base of transistor 44 _2, while being the power supply Vcc connected via the resistor 44 _3,
It is grounded through a resistor 44 _4. Transistor 44
₂ of the collector through the collector resistor 44 ₅ Power Vc
is connected to c, it is connected to one electrode of the coupling capacitor 44 _6. The other electrode of the coupling capacitor 44 ₆ is connected to the next stage of the amplifier 45. The emitter of the transistor 44 ₂ is grounded via the emitter resistor 44 ₇ and the AC bypass capacitor 44 _8. By the resistors 44 _3, 44 _4, 44 _5, 44 _7, has a configuration in which the bias of the transistor 44 ₂ is set. On the other hand, the bias changing circuit 70 includes a switch 71 that turns on and off based on a control signal S40 from the control unit 40C, and a resistor 72. Switch 71 is connected between the power source Vcc and the resistor 72, the other terminal of the resistor 72 is connected to the base of the transistor 44 _2. That is, the bias of the transistor 44 ₂ is turned on the switch 71, that has composition that varies off. Switch 71 is in the state of off, by the resistors 44 _3, 44 _4, 44 _7, the bias of the transistor 44 ₂ is set. If the switch 71 is on, the resistance 72 and the resistance 44 ₃ become parallel, each resistor 44 _3, 44 _4, 44 _7, 72, that has composition that sets the bias of transistor 44 _2.

[0009] Figure 4 is a diagram for explaining the transition of transistor 44 ₂ operating points in FIG. In this figure, the collector of the horizontal axis transistor 44 ₂ - emitter voltage V
_CE, the vertical axis represents the current I _C flowing into the collector, the base current I _B1 ~I _B7 is entered. When the switch 71 is the base current of the transistor 44 ₂ of the off state and I _B7, the operating point of the transistor 44 ₂ is made to point A on the DC load line Ld, the transistor 44 ₂ to the AC load line L _a1 The corresponding amplification will be performed. In the amplifier 44 of this embodiment, the current consumption for signal amplification is small in this state.
It is designed to have a low noise figure. Transistor 44 ₂ of the operating point when the switch 71 is turned on, a transition to point B on the DC load line Ld, the transistor 4
4 ₂ performs amplification corresponding to the AC load line L _a2. The current consumption at this time is larger than when the operating point is A, but even if the input signal is large, the power of the distortion is small. That is, it has a high saturation output characteristic. The above is the relationship between the amplifier 44 and the bias changing circuit 70. On the other hand, the amplifier 45 and the mixer 47 of the bias changing circuit 70
The parts corresponding to the above have the same configuration. From the control unit 40C
The instructions, and is configured to bias changing circuit 70 changes the bias applied to the amplifier 45 and the mixer 47
There Ru. In the amplifier 45 and the mixer 47, the mobile phone 40
The optimal operation is performed in response to the case where the signal is connected to the booster 30 and the case where the signal is not connected.

Next, the portable telephone 40 and the booster 3 shown in FIG.
The operation of 0 will be described. The switch 42 connects the node N1 of the mobile phone 40 to the booster 30. The received signal received from the antenna 31 of the booster 30 is amplified by the booster receiving unit 32 and supplied to the node N1 via the switch 42. Bandpass filter 43
Performs filtering on the received signal, the filtered reception signal
The signal is supplied to an amplifier 44. On the other hand, the booster detection circuit 60 notifies the control unit 40C that the mobile phone 40 has been connected to the booster 30. The control unit 40C instructs the bias changing circuit 70 to turn on the switch 71. Bias to the amplifier 44, is changed from the bias when the cellular phone 40 is used alone, the operating point of the transistor 44 ₂ is shifted to B. Transistor 4
4 ₂ performs amplification corresponding to the AC load line L _a2. The amplified received signals via a capacitor 44 _6, the amplifier 45
Is transmitted to Also in the amplifier 45, appropriate amplification is performed with the changed bias, and the received signal is provided to the mixer 47 via the band-pass filter 46. Mixer 47
Multiplies the received signal by the frequency signal from the local oscillator 48. Demodulator 49 demodulates the data in the received signal from the output signal of the mixer 47 gives the control unit 40C. The control unit 40C converts the demodulated data into voice or the like.
On the other hand, when performing transmission, the data supplied from the control unit 40C, is modulated by the modulator 50, the modulated data, the frequency signal multiplied is transmission signal from the local oscillator 48 in the mixer 51 is generated Is done. The transmission signal is filtered by the band pass filter 52. The amplifier 53 amplifies the filtered transmission signal, and the amplified transmission signal is filtered again by the band-pass filter 54. The amplifier 55 amplifies the transmission signal again, and the band pass filter 56 performs filtering. The transmission signal subjected to the amplification and filtering processing is provided from the node N1 to the booster transmission unit 33 in the booster 30 via the switch 42. The booster transmission unit 33
Since the transmission signal obtained from the mobile phone 40 is a small output signal, it is further amplified and radiated from the antenna 31.

[0011] cellular telephone 40, the system is in the configuration capable of transmitting and receiving without using the booster 30. When the mobile phone 40 is used alone, transmission / reception is performed via the antenna 41. At this time, the switch 71 in the bias changing circuit 70 is turned off by the instruction of the control unit 40C, and the bias for each of the amplifiers 44 and 45 and the mixer 47 is suitable when the mobile phone 40 is used alone. It is assumed. That is, the amplifier 44 has low noise figure characteristics, and the amplifier 45 and the mixer 47 have low distortion and high saturation output characteristics. The operations of other parts in the mobile phone 40 when transmission and reception are performed via the antenna 41 are the same as those when the booster 30 is used. As described above, in the present embodiment, the bias changing circuit 70 is provided, and depending on the connection of the booster 30, the mobile phone 4
The bias within 0 can be changed. Therefore, when the mobile phone 40 is used alone, transmission / reception is performed with the optimum characteristics as the mobile phone 40, and when the booster 30 is used, transmission / reception is performed with the overall characteristics including the booster 30 being optimum. It becomes possible. In addition,
The present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications.

(1) The configurations of the receiving section 40A and the transmitting section 40B are not limited to those shown in FIG. 1. For example, the number of amplifiers can be further increased. Also in this case, the receiving unit 4
If the bias for the amplifier added to 0A is changed by the bias changing circuit 70, the same effect as in the above embodiment can be expected. (2) In the above embodiment, the bias change circuit 70 changes the bias based on the connection of the booster 30. However, the change may be performed in the transmission / reception state of the mobile phone 40. For example, the mobile phone 40
In the standby state, the current consumption is set the bias so as to minimize, to increase the current consumption in the call state, it may be configured to set the best distortion characteristics against disturbance from outside. As a result, unnecessary power consumption can be suppressed, and transmission / reception with the best distortion characteristics can be performed with respect to external interference waves. (3) Although the bias change by the bias change circuit 70 is automatically performed via the control unit 40C, a switch for switching is provided outside the mobile phone 40, and the user performs the switching. The bias may be changed.

[0013]

As described [Effect Invention above in detail, according to the present invention, the bias Ru applied to the amplifying element. Thus to change the connection form status of the external device communication unit, in response to the usage This makes it possible to optimally set the cross-modulation characteristics in the communication device. Therefore, the amplification characteristics of the amplification element
For example, when using a communication device alone, it has a low noise figure characteristic.
High saturation when connecting a communication device to an external device.
Force characteristics, which allows the
Regardless of the usage pattern, always operate in the optimum state.
Can be.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing a mobile phone and a booster according to an embodiment of the present invention.

FIG. 2 is a configuration block diagram showing a conventional mobile phone and a booster.

FIG. 3 is a circuit diagram showing an example of a bias changing circuit and an amplifier in FIG. 1;

FIG. 4 is a diagram illustrating transition of an operating point of a transistor in FIG. 3;

[Explanation of symbols]

 Reference Signs List 30 booster 31, 41 antenna 40 mobile phone 40A reception unit 40C control unit 44, 45 amplifier 60 booster detection circuit 70 bias change circuit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/40 H03G 3/20 H04B 7/26

Claims (1)

(57) [Claims] 1. A communication device having an amplifying element for amplifying a received signal with amplification characteristics based on a given bias, amplifying the received signal and inputting the amplified signal to the amplifying element.
An external device by the connection status <br/> when connected to the communication device and the bias changing circuit, characterized in that it has a function of giving to the amplifying device by changing the bias for.