JP2001127658A - Receiver and portable telephone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance anti-disturbing wave performance by varying a characteristic of an active element as a mixing element so as to allow the active element to act on a characteristic with high linearity. SOLUTION: A linearity control circuit 7 detects the strength of a received signal. When the control circuit 7 detects that the strength of the received signal is comparatively high, that is, it is possible that the received level of a disturbing wave is comparatively high, the control circuit 7 supplies no bias current to the mixing element of a linearity variable mixer circuit 4. The mixing element receiving no bias current is in operation with a characteristic of a comparatively low gain and comparatively high linearity, and then the anti disturbing wave performance can be enhanced even when the conversion gain is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver having an active element as a mixing element for mixing a radio frequency reception signal and a local oscillation signal to generate an intermediate frequency reception signal, and the above-mentioned receiver. Related to mobile phones.

[0002]

In recent years, with the advance of telecommunication technology, portable wireless communication devices such as mobile phones have become widespread. By the way, in a mixer circuit employed in a receiving unit of a mobile phone, an active element such as an FET (field effect transistor) is employed as a mixing element. In this case, the FET employed as the mixing element operates with relatively high conversion gain and relatively low linearity characteristics when the bias current is supplied at a predetermined current value.
When the bias current is not supplied, it has a property of operating with relatively low conversion gain and relatively high linearity.

[0003] In the prior art, a bias current is always supplied to an FET as a mixing element at a predetermined current value. Therefore, the conventional one is
By always supplying a bias current to the FET with a predetermined current value, the FET operates with a relatively high conversion gain characteristic, so that the reception sensitivity of the received signal can be increased. Even if it is desired to increase the performance, the FET operates with relatively low linearity characteristics, so that there is a situation that the anti-disturbance performance cannot be improved.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to make an active element as a mixing element act by changing the linearity characteristic.
It is an object of the present invention to provide a receiver capable of operating an active element with relatively high linearity characteristics, thereby improving anti-jam performance, and a mobile phone including the receiver.

[0005]

According to the receiver of the present invention, the reception signal strength detection means detects the strength of the reception signal, and the linearity control means detects the reception signal strength detection means. The bias current is controlled based on the result.

That is, according to this, when the strength of the received signal is relatively small based on the detection result of the strength of the received signal detected by the received signal strength detecting means, the linearity control means is biased to the active element. If the current is controlled so as to be supplied at a predetermined current value, the active element can be operated with a relatively high conversion gain characteristic, whereby the receiving sensitivity can be increased.

On the other hand, if the linearity control means is controlled so that the bias current is not supplied to the active element when the intensity of the received signal is relatively large, the active element can be converted to a relatively low conversion gain and a relatively high level. It is possible to operate with a linear characteristic, whereby the conversion gain can be reduced, but the anti-jam performance can be improved. Also,
In this case, power consumption can be suppressed because the bias current is controlled so as not to be supplied to the active element.

As described above, by varying the bias current supplied to the active element as the mixing element,
The active element can be made to operate with its linearity characteristics varied, and the anti-interference performance can be enhanced as required.

According to the second aspect of the present invention, the linearity control means, when the strength of the received signal is relatively small, based on the detection result of the strength of the received signal detected by the received signal strength detecting means, Control is performed so that the bias current is supplied to the element with a predetermined current value, and when the intensity of the received signal is relatively large, control is performed so that the bias current is not supplied to the active element.

That is, according to this, when the intensity of the received signal is relatively small, the bias current is supplied to the active element with a predetermined current value.
The active element can be operated with a characteristic of a relatively high conversion gain, whereby the receiving sensitivity can be increased.

On the other hand, if the strength of the received signal is relatively large, no bias current is supplied to the active element, so that the active element has relatively low conversion gain and relatively high linearity characteristics. Thus, the conversion gain is reduced, but the anti-interference performance can be improved. Further, in this case, power consumption can be suppressed because the bias current is controlled so as not to be supplied to the active element.

According to a third aspect of the present invention, the reception signal strength detection means detects the strength of the reception signal, the reception signal quality detection means detects the quality of the reception signal, and the linearity control means. Controls the bias current based on the detection result of the reception signal strength detection means and the detection result of the reception signal quality detection means.

[0013] That is, according to this, the linearity control means is provided on the basis of the detection result of the reception signal strength detection means detecting the strength of the reception signal and the detection result of the reception signal quality detection means detecting the quality of the reception signal. Therefore, when the strength of the received signal is relatively small, regardless of the quality of the received signal, if the active element is controlled so that the bias current is supplied at the predetermined first current value, the active element can be converted to a relatively high level. The operation can be performed with a gain characteristic, and thereby the reception sensitivity can be increased.

On the other hand, when the intensity of the received signal is relatively high and the quality of the received signal is relatively good, the linearity control means is controlled so that the bias current is not supplied to the active element. Since no bias current is supplied to the active element, the active element can be operated with a relatively low conversion gain and a relatively high linearity characteristic in the same manner as the above-described claim 1. As a result, although the conversion gain is reduced, the anti-interference wave performance can be improved. Also in this case, since the bias current is controlled so as not to be supplied to the active element, power consumption can be suppressed.

Further, when the intensity of the received signal is relatively large and the quality of the received signal is relatively poor, the linearity control means may control the active element to have a predetermined bias current in the active element.
Is controlled so as to be supplied by a predetermined second current value larger than the current value of the active element, the active element can operate with relatively high conversion gain and relatively high linearity characteristics. Although the power is increased, it is possible to improve the anti-jam performance while securing a high conversion gain.

As described above, by varying the bias current supplied to the active element as the mixing element in the same manner as in the first aspect, the active element can be operated by varying the linearity characteristics. And, if necessary, the anti-jamming wave performance can be enhanced.

According to a fourth aspect of the present invention, the linearity control means includes a detection result that the reception signal strength detection means detects the strength of the reception signal and a detection result that the reception signal quality detection means detects the quality of the reception signal. Based on the result, when the strength of the received signal is relatively small, regardless of the quality of the received signal, control is performed such that the bias current is supplied to the active element at a predetermined first current value, and the strength of the received signal is reduced. Relatively large,
And, when the quality of the received signal is relatively good, control is performed so that the bias current is not supplied to the active element. When the strength of the received signal is relatively large and the quality of the received signal is relatively poor, Control is performed such that the bias current is supplied to the active element by a predetermined second current value larger than the predetermined first current value.

That is, according to this, when the strength of the received signal is relatively small, the bias current is supplied to the active element at a predetermined first current value regardless of the quality of the received signal. Therefore, the active element can be operated with a characteristic of a relatively high conversion gain, whereby the receiving sensitivity can be increased.

On the other hand, if the strength of the received signal is relatively high and the quality of the received signal is relatively good, no bias current is supplied to the active element. In a manner similar to that described in the item 1, the active element can be operated with relatively low conversion gain and relatively high linearity characteristics, so that the conversion gain is reduced but the anti-disturbance performance is improved. Can be. Also in this case, since the bias current is controlled so as not to be supplied to the active element, power consumption can be suppressed.

Further, the strength of the received signal is relatively large,
If the quality of the received signal is relatively poor, a bias current is supplied to the active element with a predetermined second current value larger than a normal (predetermined first current value). Therefore, the active element can be operated with a relatively high conversion gain and a relatively high linearity characteristic. As a result, although the power consumption increases, the high conversion gain and the anti-disturbance performance can be improved. be able to.

According to the fifth aspect of the present invention, in the receiving unit, the bias current supplied to the active element as the mixing element is varied, so that the active element is caused to vary in linear characteristic. Can be. By controlling the bias current not to be supplied to the active element, the mixing element can be operated with a relatively low conversion gain and a relatively high linearity characteristic. As a result, although the conversion gain is reduced, The anti-interference performance can be improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is applied to a receiving section of a portable telephone will be described below with reference to FIGS. First, FIG.
1 shows a functional block diagram of an electrical configuration of a main part of a receiving unit of a mobile phone. In the mobile phone 1, the receiving unit 2 (the receiver in the present invention) includes a low-noise amplifier circuit 3,
It comprises a linearity variable mixer circuit 4, a demodulation circuit 5 (received signal strength detection means in the present invention), a control circuit 6, and a linearity control circuit 7 (linearity control means in the present invention).

The low-noise amplifier circuit 3 amplifies the weak radio wave captured by the antenna 8 and converts it to radio frequency (RF: Radio Frequency).
ncy), and outputs the RF signal to the variable linearity mixer circuit 4. When the RF signal is input from the low noise amplifier circuit 3, the variable linearity mixer circuit 4 and the input RF signal and the local oscillation (L
O: Local Oscillation (hereinafter abbreviated as LO signal) is mixed to down-convert the RF signal to generate a reception signal (hereinafter abbreviated as IF signal) of an intermediate frequency (IF). , And outputs the generated IF signal to the demodulation circuit 5.

Upon receiving an IF signal from the variable linearity mixer circuit 4, the demodulation circuit 5 demodulates the input IF signal to extract a baseband signal, and outputs the extracted baseband signal to the control circuit 6. At the same time, the demodulation circuit 5 detects the strength of the received signal and outputs received signal strength information indicating the detected strength of the received signal to the linearity control circuit 7.

When a baseband signal is input from the demodulation circuit 5, the control circuit 6 processes the input baseband signal. When receiving the received signal strength information from the demodulation circuit 5, the linearity control circuit 7 decodes the input received signal strength information and outputs a control signal to the linearity variable mixer circuit 4 according to the result of the decoding.

FIG. 2 shows an electric circuit diagram of the above-described variable linearity mixer circuit 4. As shown in FIG. The variable linearity mixer circuit 4 includes a dual gate FET 9 (active element in the present invention) having two gate terminals as a mixing element. The low-noise amplifier circuit 3 is connected to the first gate terminal G1 of the FET 9 via the first input matching circuit 10, and the RF signal is supplied to the first gate terminal G1 of the FET 9 via the first input matching circuit 10. Input to the gate terminal G1. In this case, in the first input matching circuit 10, the capacitor 11
Blocks the DC component of the RF signal, and the impedance elements 12 and 13 match the impedance of the transmission line of the RF signal with the input impedance of the first gate terminal G1 of the FET 9.

The second input matching circuit 14 includes an FET
9, and the LO signal is input to the second gate terminal G2 of the FET 9 via the second input matching circuit 14. In this case, in the second input matching circuit 14, the capacitor 15 blocks the DC component of the LO signal, and the impedance elements 16, 17
The impedance of the signal transmission line is matched with the input impedance of the FET 9 at the second gate terminal G2.

The source terminal S of the FET 9 is grounded via a parallel circuit 20 including a resistor 18 and a capacitor 19. The drain terminal D of the FET 9 is connected to the output matching circuit 21.
The IF signal is output to the demodulation circuit 5 via the output matching circuit 21. In this case, in the output matching circuit 21, the impedance element 2
2 and capacitor 23 act as a low-pass filter for extracting the IF signal,
4 and 25 match the impedance of the transmission line of the IF signal, and the capacitor 26 blocks the DC component of the IF signal.

A drain terminal D of the FET 9 is connected to a DC power supply 29 via an impedance element 27 and a bias current variable circuit 28, and a series circuit 31 composed of the impedance element 27 and the capacitor 30.
Through the ground. The bias current variable circuit 28
For example, it is a circuit mainly composed of a transistor, and switches between an on state and an off state according to a control signal input from the linear control circuit 7.

In this case, when the bias current variable circuit 28 is on, a bias current is supplied from the DC power supply 29 to the FET 9 at a predetermined current value (for example, 5 mA). Is in the off state, no bias current is supplied from the DC power supply 29 to the FET 9.

Now, the FET 9 will be described. When mixing the RF signal and the LO signal to generate an IF signal, the FET 9 operates with relatively high conversion gain and relatively low linearity characteristics when a bias current is supplied at a predetermined current value. On the other hand, when the bias current is not supplied, it has a property of operating with relatively low conversion gain and relatively high linearity.

Next, the operation of the above configuration will be described with reference to FIG.
This will be described with reference to FIG. The linearity control circuit 7 includes a demodulation circuit 5
In the situation where the received signal strength information is input from the receiver, the received signal strength level indicated by the input received signal strength information is compared with the received signal strength reference level preset as a threshold (step S1). .

If the received signal strength level is lower than the received signal strength reference level, that is, if the received signal strength is relatively small, the linearity control circuit 7 determines “YES” in step S 1 and determines whether the bias current By outputting a control signal to the variable circuit 28, the bias current variable circuit 28 is controlled to an ON state. Thereby, the FET 9
Since the bias current variable circuit 28 is in the ON state, the bias current is supplied from the DC power supply 29 at a predetermined current value, and the bias current variable circuit 28 operates with relatively high conversion gain and relatively low linearity. (Step S2).

As described above, when the received signal strength is relatively small, it is assumed that the reception level of the desired wave is relatively small. Therefore, by supplying the bias current to the FET 9 with a predetermined current value, the FET 9 is turned on. It is possible to operate with a relatively high conversion gain characteristic, whereby the receiving sensitivity can be increased.

On the other hand, if the received signal strength level is equal to or higher than the received signal strength reference level, that is, if the received signal strength is relatively large, the linearity control circuit 7 determines "NO" in step S1. By outputting a control signal to the bias current variable circuit 28, the bias current variable circuit 28 is turned off. With this, FET
No. 9, since the bias current variable circuit 28 is in the off state, the bias current is not supplied from the DC power supply 29, and the circuit 9 operates with relatively low conversion gain and relatively high linearity characteristics (step S3). .

As described above, when the received signal strength is relatively high, it is assumed that the reception level of the interference wave may be relatively high. Therefore, the bias current is not supplied to the FET 9 so that the FET 9 can be compared. It is possible to operate with a characteristic of extremely low conversion gain and relatively high linearity, whereby the conversion gain can be reduced, but the anti-interference performance can be improved.

As described above, according to the first embodiment, the strength of the received signal is detected, and the bias current supplied to the FET 9 is controlled based on the detected result. The characteristics of the linearity can be varied and applied. When the intensity of the received signal is relatively high, that is, when it is assumed that the reception level of the interference wave may be relatively high, the bias current is not supplied to the FET 9 so that the FET 9 is relatively low. It is possible to operate with a conversion gain and relatively high linearity characteristics, whereby the conversion gain can be reduced, but the anti-interference performance can be improved. Further, in this case, since no bias current is supplied to the FET 9, power consumption can be suppressed.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described with reference to FIGS.
The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, different parts will be described.
First, FIG. 4 shows, as a functional block diagram, an electrical configuration of a main part of a receiving unit of a mobile phone. Mobile phone 41
, The receiving unit 42 includes a low-noise amplifier circuit 3, a variable linearity mixer circuit 43, a demodulation circuit 5, a control circuit 44 (a received signal quality detection unit in the present invention), and a linearity control circuit 4.
5 is provided.

When the baseband signal is input from the demodulation circuit 5, the control circuit 44 performs signal processing on the input baseband signal, and at the same time, detects the quality of the received signal and indicates the quality of the detected received signal. The signal quality information is output to the linearity control circuit 45. In this case, the quality of the received signal is indicated by a bit error rate, a frame error rate, a desired signal to interference signal ratio, or the like.

When the received signal strength information is input from the demodulation circuit 5 and the received signal quality information is input from the control circuit 44, the linearity control circuit 45 decodes the received received signal strength information and received signal quality information. , And outputs a control signal to the linearity variable mixer circuit 43 in accordance with the decoded result.

Next, FIG. 5 shows a linearity variable mixer circuit 43.
FIG. Linearity variable mixer circuit 43
Is different from the linear variable mixer circuit 4 described in the first embodiment in that a bias current variable circuit 46 is connected instead of the bias current variable circuit 28. The bias current variable circuit 46 is a circuit mainly composed of, for example, an FET. ).

Now, the FET 9 will be described. As described in the first embodiment, when the FET 9 mixes the RF signal and the LO signal to generate the IF signal, the bias current is supplied with a predetermined first current value (for example, 5 mA). When the bias current is not supplied, the device operates with relatively low conversion gain and relatively high linearity when the bias current is not supplied. have. In addition, FET9
In addition, when the bias current is supplied by a predetermined second current value (for example, 15 mA) larger than the predetermined first current value, a relatively high conversion gain and a relatively high linearity are provided. It also has the property of acting with the following characteristics.

Next, the operation of the above configuration will be described with reference to FIG.
This will be described with reference to FIG. The linearity control circuit 45 receives the received signal strength information from the demodulation circuit 5 and
In the situation where the received signal quality information has been input from the receiver, the received signal strength level indicated by the input received signal strength information is compared with a received signal strength reference level preset as a threshold (step S11). .

If the received signal strength level is lower than the received signal strength reference level, that is, if the received signal strength is relatively small, the linearity control circuit 45 proceeds to step S11.
Is determined to be “YES”, and the bias current variable circuit 4
6 to output a control signal to control the current value of the bias current to a predetermined first current value. Thereby, F
ET9 is a DC power supply 29, the bias current of which is a predetermined first.
, And operates with relatively high conversion gain and relatively low linearity characteristics (step S12).

As described above, when the received signal strength is relatively small, it is assumed that the reception level of the desired wave is relatively small. Therefore, regardless of the received signal quality, the bias current is supplied to the FET 9 by the predetermined first signal. By supplying by the current value,
The FET 9 can be operated with a characteristic of a relatively high conversion gain, whereby the receiving sensitivity can be increased.

On the other hand, if the received signal strength level is equal to or higher than the received signal strength reference level, that is, if the received signal strength is relatively large, the linearity control circuit 45 determines “NO” in step S11. Then, the received signal quality level indicated by the received received signal quality information is compared with a received signal quality reference level preset as a threshold (step S13).

If the received signal quality level is equal to or higher than the received signal quality reference level, that is, if the received signal quality is relatively good, the linearity control circuit 45 proceeds to step S1.
In step 3, the determination is "YES", and the control signal is output to the bias current variable circuit 46 to control the current value of the bias current to zero. As a result, the bias current is not supplied from the DC power supply 29 to the FET 9, and the FET 9 operates with a relatively low conversion gain and a relatively high linearity characteristic (step S14).

As described above, when the received signal strength is relatively large and the received signal quality is relatively good,
Since it is assumed that the reception level of the interference wave is relatively small,
By not supplying the bias current to the FET 9, the FE
T9 can be operated with relatively low conversion gain and relatively high linearity characteristics, which can improve the anti-interference performance, although the conversion gain is low.

On the other hand, if the received signal quality level is lower than the received signal quality reference level, that is, if the received signal quality is relatively poor, the linearity control circuit 45 returns “NO” in step S13. By making a determination and outputting a control signal to the bias current variable circuit 46, the current value of the bias current is controlled to a predetermined second current value. As a result, the bias current is supplied from the DC power supply 29 by the predetermined second current value to the FET 9, and the FET 9 operates with relatively high conversion gain and relatively high linearity characteristics (step S15). ).

As described above, when the received signal strength is relatively high and the received signal quality is relatively poor, it is assumed that the reception level of the interference wave is relatively high,
By supplying a bias current to the FET 9 at a predetermined second current value, the FET 9 can operate with relatively high conversion gain and relatively high linearity characteristics, thereby ensuring high linearity. Also, the receiving sensitivity can be increased.

As described above, according to the second embodiment, the intensity of the received signal and the quality of the received signal are detected, and the bias current supplied to the FET 9 is controlled based on the detected result. Therefore, similarly to the above-described first embodiment, the FET 9 can be operated with the linearity characteristics being varied. When the strength of the received signal is relatively large and the quality of the received signal is relatively good,
In other words, when it is assumed that the reception level of the interference wave is relatively small, the bias current is not supplied to the FET 9 so that the FET 9 can operate with relatively low conversion gain and relatively high linearity. Thus, although the conversion gain is reduced, the anti-jam performance can be improved. Further, in this case, since no bias current is supplied to the FET 9, power consumption can be suppressed.

When the strength of the received signal is relatively high and the quality of the received signal is relatively poor, that is, when the reception level of the interference wave is assumed to be relatively high, the bias current is supplied to the FET 9. Is supplied at a predetermined second current value, the FET 9 can operate with a relatively high conversion gain and a relatively high linearity characteristic.
The anti-interference performance can be improved.

(Other Embodiments) The present invention is not limited to the above embodiment, but can be modified or expanded as follows. The present invention is not limited to the configuration applied to the reception unit of the mobile phone, but may be a configuration applied to the reception unit of another device as long as it generates an IF signal by mixing an RF signal and an LO signal. The bias current variable circuit in the first embodiment may have another configuration as long as it controls on / off of the bias current.
The bias current variable circuit according to the second embodiment can change the bias current continuously (in an analog manner).
Other configurations may be used.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a first embodiment of the present invention.

FIG. 2 is an electric circuit diagram

FIG. 3 is a flowchart showing control contents.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 5 is a diagram corresponding to FIG. 2;

FIG. 6 is a diagram corresponding to FIG. 3;

[Explanation of symbols]

In the drawings, 1 is a mobile phone, 2 is a receiving unit (receiver), 5 is a demodulation circuit (received signal strength detection means), 7 is a linearity control circuit (linearity control means), 9 is a dual gate FET (mixing element) , An active element), 41 is a mobile phone, 42 is a receiver (receiver), 44 is a control circuit (received signal quality detecting means), and 45 is a linearity control circuit (linearity control means).

Claims (5)

[Claims] 1. A relatively high conversion gain when a bias current is supplied at a predetermined current value as a mixing element for mixing a radio frequency reception signal and a local oscillation signal to generate an intermediate frequency reception signal. And receivers with active elements that have relatively low conversion gain and relatively high linearity characteristics when no bias current is supplied, and the received signal strength And a linearity control means for controlling a bias current based on a detection result of the reception signal strength detection means. 2. The linearity control means controls the bias current to be supplied to the active element at the predetermined current value when the intensity of the received signal is relatively small, so that the intensity of the received signal is relatively small. 2. The receiver according to claim 1, wherein when it is larger, control is performed such that a bias current is not supplied to the active element. 3. A mixing element that mixes a radio frequency reception signal and a local oscillation signal to generate an intermediate frequency reception signal when a bias current is supplied at a predetermined first current value. It operates with a high conversion gain and a relatively low linearity characteristic, and operates with a relatively low conversion gain and a relatively high linearity characteristic when no bias current is supplied. Detecting the strength of a received signal in a receiver having an active element that operates with relatively high conversion gain and relatively high linearity characteristics when being supplied by a predetermined second current value greater than the current value Receiving signal strength detecting means, receiving signal quality detecting means for detecting the quality of the received signal, A receiver for controlling a bias current based on a detection result of the reception signal quality detection means. 4. The linearity control means according to claim 1, wherein when the intensity of the received signal is relatively small, a bias current is supplied to said active element by said predetermined first current value regardless of the quality of the received signal. When the intensity of the received signal is relatively large and the quality of the received signal is relatively good, control is performed so that the bias current is not supplied to the active element, and the intensity of the received signal is relatively large. 4. The receiver according to claim 3, wherein when the quality of the received signal is relatively poor, control is performed such that a bias current is supplied to the active element with the predetermined second current value. 5. A mobile phone comprising the receiver according to claim 1 as a receiver, and receiving radio waves transmitted from a base station by the receiver.