JPH0946152A - Wireless transceiver - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the power amplification efficiency of a high power amplifier (HPA) and reduce the power consumption. Another object is to realize a transmission power control circuit system that accurately controls the transmission power level in a wide range. According to the transmission power control signal from the baseband, the transmission power control circuit 8 increases / decreases the gain of the variable gain amplifier 4 and the FET used in the HPA 3 according to the output of the gate voltage control circuit output level determination circuit 7. Control the gate voltage. [Effect] The gate voltage of the FET of the HPA is controlled according to the transmission power level to reduce the DC input to the HPA when the transmission power level is small, and the HP is used when the transmission power level is small.
By increasing the efficiency of A, power consumption is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmitter / receiver, and more particularly to a transmission power control circuit for a high frequency section of a radio transmitter / receiver such as a mobile phone.

[0002]

2. Description of the Related Art Conventionally, there has been known a method of adjusting a gain or an attenuation amount by providing a variable gain amplifier or a variable attenuator in a high frequency section when changing a transmission power level of a radio transceiver. For example, as a method of changing the transmission power level of a mobile wireless terminal such as a mobile phone, a high output amplifier (HPA: High) including a variable gain amplifier according to a transmission power control signal.
An example of increasing / decreasing the gain of h Power Amplifier is the academic society (The Institute of Electronics and Communication Engineers Technical Report “ED92-11
7, MW92-120, ICD92-138 "Technical trend of mobile phones and demands for devices).

The prior art will be described below by taking the above report as an example. FIG. 6 is a block diagram showing the configuration of a conventionally known mobile telephone mobile radio terminal. In the figure, an audio signal to be transmitted from a baseband unit 11 is modulated by a modulator 5, amplified by HPA 3 to a predetermined power, and transmitted via an antenna duplexer 2 and an antenna 1 for separating a transmitted wave and a received wave. . At this time, according to the transmission power control signal from the baseband unit 11, the transmission power control circuit 8 increases or decreases the gain of the variable gain amplifier provided in the HPA 3 to set it to a predetermined transmission power. The received signal passes through an antenna 1, a low noise amplifier (LNA) 9 and a demodulator 10 and then a baseband unit 11
Is added to The transmission power control signal is generated by the controller in the baseband unit 11 according to the transmission power instructed in the reception signal.

[0004]

The control range of the transmission power level of a mobile phone varies depending on the system, but generally requires a relatively wide range of 20 to 80 dB (about 20 dB for GSM system and about 80 dB for CDMA system). There is. On the other hand, in a conventional mobile phone, particularly a mobile phone that handles digital signals, the input / output characteristics of the HPA are required to be linear, so that the power operation characteristics of the output stage are set near the A class operating point. For example, when the power amplifier is composed of FETs, the gate bias voltage is set so that the drain current becomes about 1/2 of the saturation current (Idss). Therefore, not only when the transmission power level is high, but also when the transmission power level is low, almost the same DC current flows, and when the transmission power level is low, the HPA efficiency is remarkably reduced, resulting in a short battery life. Therefore, the usable time of the entire terminal is shortened. Further, in the CDMA system, it is necessary to accurately control the transmission power level in an extremely wide range of 80 dB, and it is extremely difficult to realize this only with a variable gain amplifier (AGC) in the HPA. There was

An object of the present invention is to realize a transmission power control circuit that reduces direct current input to the HPA when the transmission power level is low and increases the efficiency of the HPA when the transmission power level is low, so that a radio transceiver can be used. It is to realize the increase of time. Another object of the present invention is to achieve the above object and to realize a wireless transceiver having a transmission power control circuit suitable for controlling the transmission power level in a wide range with high accuracy.

[0006]

In order to achieve the above object, the present invention provides a bias control circuit for controlling the transmission high frequency power with a transmission power control signal and controlling the bias of the power amplification circuit in the HAP. It was The bias control circuit may be supplied with a signal of which the level of the transmission power control signal from the baseband has been determined or may be supplied with a signal of which the level of the received signal has been determined.

In a further preferred form of the transmission power control circuit of the present invention, a variable attenuator is provided on the input side of the variable gain amplifier, and the transmission power control circuit controls the variable gain amplifier and the variable attenuator. To do. In particular, a coarse attenuator having a wide variable range is adjusted by a variable attenuator, and a signal obtained by extracting a part of the output of the HAP and the transmission power control signal is used to finely adjust the gain of the variable gain amplifier. Configure a power control circuit.

[0008]

[Operation] HPA composed of FETs operating in the linear region
Fig. 3 shows the relationship between the output level of the
This will be described below. In the figure, the operating point (bias voltage) Vg1 of the gate voltage is about a half of the saturated drain current, and is generally called the A class operating point. At this operating point Vg1, the amplitude ΔVg of the input signal at the gate can be maximized within the range of linear operation, and the output during linear amplification operation can be maximized. However, if the input signal is small,
It becomes a form that a small AC amplitude rides on a large DC current,
The conversion efficiency of the AC signal to the DC input is significantly reduced. In the present invention, in order to prevent the efficiency from decreasing when the input signal (transmission signal) is small, the operating point Vg of the gate voltage is lowered to set the operating point where the drain current in the absence of signal is small. For example, it can be seen that linearity can be maintained even at the Vgn point in the figure if the input signal is small. Therefore, it is possible to change the gate bias voltage according to the input signal level or the output signal level, reduce the DC input when the transmission signal is small, and suppress the battery consumption as much as possible.

As a method of controlling the transmission power level,
It is extremely difficult to realize a variable width close to 80 dB with only one variable gain amplifier with high accuracy.
It is about 30 dB. Therefore, in the preferred embodiment of the present invention, a variable attenuator is provided on the input side of the HPA of the transmission unit in order to perform the transmission power control in a wide range and with high accuracy, and the transmission that is expected to be necessary depending on the magnitude of the reception power is first provided. Set the value of the attenuator to the value of power. The variable range of the attenuation amount in this case is almost the same as the variable range of the transmission power required for the terminal, but the accuracy is not so required. Then, the signal from the baseband section is compared with the actual transmission power and set to an accurate value by another variable gain amplifier. With such a configuration in which the two systems of power control circuits are used together, power control in a wide range and with high accuracy is realized.

[0010]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 is a block diagram showing the configuration of an embodiment of a mobile phone mobile radio terminal according to the present invention. This embodiment increases or decreases the gain of the variable gain amplifier according to a transmission power control signal from a baseband processing unit (hereinafter abbreviated as a baseband unit) and determines HPA according to the value of the transmission power control signal that determines the transmission power level. It controls the gate voltage of the constituent FETs.

In the figure, a transmission signal such as a voice signal from the baseband unit 11 is modulated by a modulator 5 and then converted by a variable gain amplifier (AGC) 4 into a signal of a predetermined level. The output of the variable gain amplifier (AGC) 4 is HPA3.
Then, it is amplified to a predetermined electric power and transmitted through the antenna duplexer 2 and the antenna 1 which separate the transmission wave and the reception wave. At this time, the variable gain amplifier (AGC) 4 is connected to the baseband unit 11
The transmission power control circuit 8 increases or decreases the gain of the variable gain amplifier 4 in accordance with the transmission power control signal from to set the output at a predetermined level. The received signal passes through the antenna 1, the low noise amplifier (LNA) 9, and the demodulator 10, and then the baseband unit 1
Added to 1. The above-mentioned part is substantially the same as the configuration of a conventionally known mobile phone mobile radio terminal. For simplification of the drawing, a filter, a frequency synthesizer, etc. are omitted.

In this embodiment, the level determination circuit 7 further determines the transmission power control signal, and the gate voltage control circuit 6 controls the bias voltage of the amplifier circuit element of the HPA 3 based on the determination result.

FIG. 2 is a circuit diagram showing a circuit configuration of a main part of the embodiment shown in FIG. In this embodiment, an FET is used for the HPA 3 and a dual gate FET is used for the variable gain amplifier 5. The transmission power control signal is the baseband unit 11
Made by Inner Controller. Transmission power control signal,
Table 1 shows the relationship between the attenuation amount of the variable gain amplifier 5 and the bias (gate) voltage of the HPA 3.

[0014]

[Table 1]

The transmission power control signals are S1, S2, and S3.
This is a bit code signal, and the variable gain amplifier 5 has an attenuation of 4
Variable in 7 ways in dB. The gate voltage of HPA3 is V
Variable in three ways, g1, Vg2, and Vg3.

In FIG. 2, transmission power control signals S1 and S
Part of S2 and S3 is converted into a predetermined AGC gate voltage drive signal by the transmission power control circuit 8 composed of a digital-analog converter, and added to the second gate of the dual gate FET1 via the resistor R1. The signal to be transmitted is applied to the first gate of the dual gate FET1 via the coupling capacitance C4. The variable gain amplifier 4 including the FET 1 imparts a predetermined attenuation to the high frequency input signal and applies it to the gate of the FET 2 that constitutes the HPA 3 via the coupling capacitance C1. FE
The source electrode of T1 is grounded via a resistor R3 and a capacitor C4, and the drain voltage Vd is applied to the drain electrode via an inductor L3.

The other part of the transmission power control signals S1, S2, S3 generate switch drive signals w1, w2, w3 by a level judgment circuit 7 having logic gates G1, G2 and G3. The gate voltage control circuit 6 uses the switch drive signals w1, w2, w3 to generate the gate bias power supply Vg1,
One of Vg2 and Vg3 is selected and applied to the gate terminal of FET2 of HPA3 as a bias voltage. The output signal of the FET2 that operates with the selected bias voltage is sent to the antenna duplexer and the antenna via the coupling capacitance C2. In the figure, an inductor L2 is an element that blocks the inflow of high-frequency components into the DC power supply Vb.

FIG. 4 shows the input / output characteristics of the HPA 3 in the above embodiment. Vg1 requires the highest transmission power, Vg2 slightly lowers the transmission power, and Vg3.
Is the case where the transmission power is sufficiently low. The level determination circuit 7 sets the gate voltage to Vg when the attenuation amount becomes 0 dB.
1, the gate voltage is set to Vg2 when the control signal has an attenuation of 4 dB, and the gate voltage control circuit 6 is set to set the gate voltage to Vg3 when the control signal has an attenuation of 8 dB or more. send. If the gate voltage is set to Vg3 when the control signal is such that the attenuation amount is 8 dB or more, even if the gate voltage is finely controlled by the attenuation amount of 8 dB or more, the decrease in the battery consumption amount is small. This is because the effect of extending the life cannot be expected so much.

FIG. 5 is a block diagram showing the configuration of another embodiment of the mobile telephone mobile radio terminal according to the present invention. In this embodiment, the power consumption of the high frequency circuit is reduced and the variable range of the transmission power level is further widened. In particular, the HPA bias control for reducing the power consumption and the control signal for varying the transmission power level are obtained from the received signal. That is, the transmission power is controlled by extracting a part of the reception signal and comparing the first means for controlling the transmission power according to the reception signal level with the part of the transmission signal and the transmission power control signal from the baseband. The second means is provided.

In the figure, a part of the received signal from the LNA 9 is taken out by the coupler 12-1, and the A / D converter 1
At 4, a code signal to be the transmission power control signal is obtained. The output code signal of the A / D converter 14 is applied to the level determination circuit 15 and the transmission power control circuit 16. The reception signal level represents the distance from the base station. When the reception level is low, it indicates that the distance to the base station is long, and the amount of attenuation of the variable attenuator 13 inserted on the transmission side is reduced to increase the transmission power. There is a need. Therefore, the transmission power control circuit 16 sets the attenuation amount of the variable attenuator 13 included in the transmission system to a predetermined value according to the received signal level. In the level determination circuit 15, the gate voltage control circuit 17 sets the gate voltage of the HPA 3 based on the magnitude of the received signal level. Table 2 shows an example of the relationship between the magnitude of the received signal level and the gate voltage, which is divided into three stages.

[0021]

[Table 2]

At a low reception level of Vr1 or lower, the operating point is close to that of Vg1 and in the class A, and above that, the current is slightly reduced to Vg2 close to the AB class, and when the level is higher than Vg2, the current is even smaller. Vg3
Set to.

The switching of the attenuation amount of the variable attenuator 13 is a rough adjustment in a wide range. Therefore, in the second transmission power control circuit 18, a part of the high frequency output signal which is the output of the HPA 3 is taken out by the coupler 19, compared with the transmission power control signal from the baseband unit 11, and AG is calculated by the difference.
Control the gain of C4. Incidentally. The transmitting / receiving antenna 1, the antenna duplexer 2, the modulator 5, and the demodulator 10 are the same as those in the embodiment of FIG. In this embodiment, the level of a wide range can be controlled by the simple variable attenuator 13. Therefore, the AGC 4 can be realized by a circuit element having a narrow variable range.

The embodiments of the present invention have been described above.
The present invention is not limited to the above embodiment. For example, although the transmission power control signal is the signal from the baseband unit 11 in the embodiment of FIG. 1, the transmission power control signal may be generated from the reception signal as shown in FIG. further,
In the embodiment of FIG. 1, a variable attenuator may be provided on the input side of the variable gain amplifier 5, and the transmission power control signal from the baseband unit 11 may be used to control the variable attenuator and the variable gain amplifier 5.

[0025]

According to the present invention, the gate voltage of the FET used in the HPA is controlled according to the transmission power level to reduce the direct current input to the HPA when the transmission power level is small, and thus the transmission power is reduced. When the level is small, the efficiency of HPA can be improved and the usable time of the entire terminal can be increased. Also, a part of the received signal is taken out, the first means for controlling the transmission power according to the signal level and a part of the transmitted signal is taken out, and the transmission power control signal from the baseband is compared to control the transmission power. By adopting a configuration in which the second means is also used, it is possible to realize a transmission power control circuit system suitable for controlling the transmission power level with high precision in an extremely wide range.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a wireless transmission / reception device according to the present invention.

FIG. 2 is a circuit diagram of a main part of FIG.

FIG. 3 is an input / output characteristic diagram of an FET for explaining the operation of the present invention.

FIG. 4 is a diagram showing a gate bias point of an FET.

FIG. 5 is a block diagram showing the configuration of an embodiment of a wireless transmission / reception device according to the present invention.

FIG. 6 is a block diagram showing the configuration of a conventional wireless transmission / reception device.

[Explanation of symbols]

1 ... Transmitting / receiving antenna, 2 ... Antenna duplexer, 3 ... HP
A, 4 ... AGC, 5 ... Modulator, 6 ... Gate voltage control circuit, 7 ... Level determination circuit, 8-1, 8-2 ... Transmission power control circuit, 9 ... LNA, 10 ... Demodulator, 11 ... Baseband Part, 12-1, 12-2 ... Coupler, 13 ... Variable attenuator.

Claims (7)

[Claims] 1. A high-frequency signal reception circuit and a transmission circuit,
A high frequency power amplifier for amplifying a transmission signal by the transmission circuit, a variable gain amplifier for changing an input level of the high frequency power amplifier, a transmission power control circuit for controlling the gain of the variable gain amplifier by a transmission power control signal, A bias control circuit for controlling a bias of an amplification circuit element in a high frequency power amplifier, and a level determination circuit for determining the magnitude of the transmission power level of the transmission power control signal and driving the bias voltage control circuit. Wireless transmitter and receiver. 2. The radio transmitter / receiver according to claim 1,
2. The radio according to claim 1, wherein a variable attenuator is provided on the input side of the variable gain amplifier, and the transmission power control circuit is a circuit for controlling the variable attenuator and controlling the gain of the variable gain amplifier. Transceiver. 3. The radio transmitter / receiver according to claim 1, wherein the amplifier circuit element is an FET, and the bias control circuit is a gate voltage control circuit for controlling a gate voltage of the FET. 4. The wireless transmitter / receiver according to claim 1, wherein the transmission power control signal is supplied from a baseband processing unit of the wireless transmitter / receiver. 5. The radio transmitter / receiver according to claim 1, further comprising a circuit for extracting the transmission power control signal from a signal of a reception signal of the reception circuit. 6. A variable gain amplifier having a high frequency signal reception circuit, a transmission circuit, and a baseband signal processing section, wherein the transmission circuit changes the level of the transmission signal, and a high frequency power amplifier for amplifying the output of the variable gain amplifier. Variable gain means for varying the input level of the variable gain amplifier, first detecting means for detecting a received signal level, and first transmission power for controlling the variable gain means by the output of the first detecting means. A control circuit, a level determination circuit for determining the level of the output of the first detection means, a bias control circuit for controlling the bias of an amplification circuit element in the high frequency power amplifier by the output of the level determination circuit, and the high frequency Second detecting means for detecting the output level of the power amplifier, the level of the transmission power control signal from the baseband signal processing section, and the high frequency power. Wireless transceiver apparatus characterized by having a second transmission power control circuit for controlling the gain of the comparison to said variable gain amplifier output level of the amplifier. 7. The amplifier circuit element is an FET, the bias control circuit is a gate voltage control circuit for controlling the gate voltage of the FET, the variable gain means is a variable attenuator, and the gate voltage control circuit. 8. The wireless transmission / reception device according to claim 7, wherein is a circuit for reducing the drain current of the FET when the output of the high frequency power amplifier is low.