JPH04207233A - Diversity reception circuit - Google Patents

Abstract

PURPOSE:To present a diversity reception circuit having a small circuit scale and a low current consumption by operating only one of plural low noise amplifiers in accordance with a diversity switching control signal. CONSTITUTION:The high frequency signal inputted from a high frequency input terminal 1 is demodulated by a double super-heterodyne consisting of a front end, which consists of a low noise amplifier 20 having the switching function and a first mixer 3, and an IF demodulator consisting of a first IF BPF 5 and following elements. The switching control signal inputted to a switching control signal terminal 22 is periodically determined or is determined by comparison with the reception level before the change for the purpose of coping with the quick drop of the reception electric field due to fading. A bias voltage generating circuit 2 generates a bias voltage in accordance with the switching control signal so that one low noise amplifier is operated, and this voltage is applied to the low noise amplifier 20 having the switching function.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a diversity receiving circuit which is a means for overcoming fading peculiar to mobile communications.

Conventional technology As a means to overcome the fading peculiar to mobile communications, a post-detection selective diversort receiving circuit is widely used, and is described, for example, in the Institute of Electronics, Information and Communication Engineers Communication Systems Study Group Material C382-7 of 1981. The configuration is known.

A conventional guideline receiving circuit will be described below with reference to FIG.

In FIG. 4, 1 is a high frequency input terminal, 2 is a low noise amplifier, 3 is a first mixer, 4 is a first local oscillator, and 5 is a first I
FBPF, 5 is the first IF amplifier, 7 is the second mixer, 8 is the second local oscillator, 9 is the second IFBPF, 10 is the second IP
amplifier, 11 is a limiter, 12 is a discriminator,
13 is a switching controller, and 14 is a demodulation output terminal.

The high frequency signal input from the high frequency input terminal 1 is demodulated by a two-system double superheterodyne receiver consisting of a front end consisting of a low noise amplifier 2 and a first mixer 3, and an IF/demodulation section after the 11th FBPF5. be done.

Will the sudden drop in the received electric field caused by fading, which is unique to mobile communications, lead to deterioration of the received S/N?
In this post-detection selection diversity receiving circuit, depending on the level of the second IF output input to the switching controller 13,
Deterioration of the received S/H is relieved by performing branch switching, selecting the demodulated output with a higher level, and outputting it from the demodulating terminal 14.

Problem to be solved by the invention However, although the above configuration reduces the deterioration of the received S/N due to the sudden drop in the received electric field due to fading, it requires two receiving circuits and increases the circuit scale. At the same time, the current consumption also doubles.

The present invention solves the above problems of the prior art, and aims to provide a diversity receiving circuit with a small circuit scale and low current consumption.

Means for Solving the Problems The present invention provides a switching function for a plurality of amplifier groups provided in a receiver front end section to operate only one amplifier in response to a diversity switching control signal. The object of the present invention is to provide a diversity receiving circuit that has good receiving sensitivity and linearity, has a significantly reduced circuit scale, and reduces current consumption.

Effect of the Invention The present invention provides a plurality of low-noise amplifiers in the front-end section that control the performance of the receiver, corresponding to the number of diversity branches, and switches the plurality of low-noise amplifiers into a group of low-noise amplifiers in accordance with a yever branch switching control signal. By applying a bias voltage to a group of low-noise amplifiers so that only one amplifier is activated and the others are inactive, receiving sensitivity is not reduced, the circuit scale is significantly reduced, and current consumption is reduced. A diversity receiving circuit has been realized.

As described above, the present invention provides a receiver with a plurality of low-noise amplifiers corresponding to the number of diversity branches, and has a switching function to operate only one of the low-noise amplifiers in response to a switching control signal. This provides a diversity receiving circuit with good receiving sensitivity and linearity, significantly reduced circuit scale, and reduced current consumption.

EXAMPLE A first example of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a diversity receiving circuit in a first embodiment of the present invention. In Figure 1, 2
0 is a low noise amplifier having a switching function, 21 is a bias voltage generation circuit, and 22 is a switching control signal terminal.

Components with the same numbers as in FIG. 4 have the same functions as in FIG.

The operation of the above configuration will be explained below. The high frequency signal input from high frequency input terminal 1 is
A front end consisting of a low noise amplifier 20 having a switching function and a first mixer 3 and a first IFBPF 5
The signal is then demodulated by a double super-hetero gain receiver consisting of an IP demodulator.

In order to cope with a sudden drop in the received electric field caused by fading, the switching control signal input to the switching control signal terminal 22 is determined periodically or by comparing it with the receiving level before change.

Accordingly, the bias voltage generation circuit 21 generates a bias voltage so that only one of the low-noise amplifiers operates, and this voltage is applied to the low-noise amplifier 20 having a switching function.

In this configuration, a plurality of low-noise amplifiers with switching functions are provided corresponding to the number of diversity branches, and by switching them using a switching control signal, the IF/demodulator can be made into one system. circuit scale,
It is possible to significantly reduce current consumption. In addition, by providing a switching function to the low-noise amplifier, not only is there less deterioration in the noise figure compared to a configuration in which a switch circuit is inserted before the low-noise amplifier, but also a configuration in which a switch circuit is inserted after the low-noise amplifier. It is possible to realize a receiver with low distortion compared to the above.

As is clear from the above description, according to this embodiment, a plurality of low-noise amplifiers having a switching function are provided corresponding to the number of diversity branches, and by switching them using a switching control signal, The IP/demodulator can be combined into one system, which can significantly reduce the circuit scale and reduce current consumption. In addition, by providing a switching function to the low-noise amplifier, compared to a configuration in which a switch circuit is inserted before the low-noise amplifier,
Not only can a good noise figure be obtained, but also a receiver with lower distortion can be realized with less current than a configuration in which a switch circuit is inserted after a low-noise amplifier.

In the above embodiments, the limiter/discriminator method is used for the demodulation circuit, but it goes without saying that the present invention is not limited to the modulation/demodulation method.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a diagram showing a low-noise amplifier having a switching function, which is a main part of a diversity receiving circuit in a second embodiment of the present invention. Figure 2 (al is a current control circuit using a circuit consisting of a 3-terminal active element and a resistor, and fbl in the same figure is a current control circuit composed of only resistors. 30 is a power supply terminal, 31 to 34 (for switching) is a bias terminal, 35 to 36 are high frequency input terminals, 37 is an output terminal, 38 is a current control terminal, 40 to 41 are input matching circuits, 42 is an output matching circuit, Q1 to Q2 are switching transistors, Q3 ~Q4 is a high frequency amplification transistor,
Q5 is a current control transistor, C1 to C3 are capacitors for bias voltage supply, C4 is emitter capacitance, R1 is output load resistance, R2-R6 are bias voltage supply resistors, R7-R
8 is a current control resistor that determines the circuit current.

The operation of the above configuration will be explained below. The circuit current is controlled by the voltage applied to the current control terminal 38, the current control transistor Q5, and the current control resistor R7 in the figure fal, and by the current control resistor R8 in the figure (bl). ), there is no voltage drop in the current control transistor, and operation is possible up to a lower power supply voltage than in the embodiment shown in fa) of the same figure. High frequency input terminals 35-36
The high-frequency signal input to the input matching circuits 40 to 41 causes either the transistor pair Ql and Q3 or the transistor pair Q2 and Q4 to operate according to the switching bias voltage generated in conjunction with the switching control signal. , the other becomes inactive. That is, the high frequency input terminal 35
36 is selected and outputted from the output terminal 37 via the output matching circuit 42. The bias voltage supply capacitors 01 to C3 and the emitter capacitor C4 are capacitors that realize high frequency grounding.

As is clear from the above description, according to this embodiment, the transistors are stacked vertically, and the IF - The demodulation section can be reduced to one system, which can significantly reduce the circuit scale and reduce current consumption. In addition, by providing a switching function to the low-noise amplifier in this way, not only can a better noise figure be obtained compared to a configuration in which a switch circuit is inserted before the low-noise amplifier, but also a switch circuit can be inserted after the low-noise amplifier. Even compared to a configuration in which a circuit is inserted, a receiver with low distortion can be realized with less current.

Next, a third embodiment of the present invention will be described.

FIG. 3 is a diagram showing a low-noise amplifier having a switching function, which is a main part of a diversity receiving circuit in a third embodiment of the present invention. The difference between FIG. 3 and FIG. 2 is that a 2-gate FET is used as the 3-terminal active element. Q6 to Q7 are two-gate FETs that have both high frequency amplification and switching functions. Components with the same numbers as in FIG. 2 have the same functions as in FIG.

The operation of the above configuration will be explained below. 3
By using a 2-gate FET as a terminal active element, applying a high frequency input to the first gate and applying a bias voltage to the second gate, the same effect as the configuration of vertically stacking transistors shown in Figure 2 can be achieved with fewer elements. can get.

As described above, according to this embodiment, it is possible to provide a switching function to a low-noise amplifier with a small number of elements, and the reception sensitivity and
It is possible to realize a diversity receiving circuit with good linearity, significantly reduced circuit scale, and reduced current consumption.

Note that although the above embodiments have been described with reference to an example in which the number of diversity branches is two, it goes without saying that the present invention can also be applied to any number of N groups in which N is two or more.

Effects of the Invention As described above, the present invention provides a plurality of low-noise amplifiers each having a switching function according to the number of diversity branches, and is configured to switch between them using a switching control signal, thereby improving the IP/demodulation section. It is possible to use only one system, which greatly reduces the circuit scale and reduces current consumption. Furthermore, by providing a switching function to the low-noise amplifier, not only can a better noise figure be obtained compared to a configuration in which a switch circuit is inserted before the low-noise amplifier, but also a switch circuit can be inserted after the low-noise amplifier. Even compared to the configuration in which the wire is inserted, it is possible to create a receiver with lower distortion using less current.
Its industrial effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a diversity receiving circuit according to a first embodiment of the present invention, and FIG. 2 is a second embodiment of a low-noise amplifier having a switching function, which is the main part of the diversity receiving circuit according to the present invention. 3 is a circuit diagram showing a third embodiment of a low-noise amplifier having a switching function, which is the main part of the diversity receiving circuit of the present invention, and FIG. 4 is a block diagram showing a conventional diversity receiving circuit. It is a wiring diagram. 20...Low noise amplifier, 21...Bias voltage generation circuit, 22...Switching control signal terminal, 30...Power supply terminal, 31-34...Switching bias terminal, 3
5 to 36...high frequency input terminal, 37...output terminal,
38... Current control terminal, 40-41... Input matching circuit, 42... Output matching circuit, Q1-Q2... Switching transistor, Q3-Q4... High frequency amplification transistor, Q5...・Current control transistor, Q
6~Q7... 2-game 1-FET with both high frequency amplification and switching functions 5C1~C3... Capacitor for bias voltage supply, C4... Emitter capacitance, R1... Output load resistance, R2-R6...・Bias voltage supply resistance, R7
-R8...Current control resistance. Figure 2 Figure 6

Claims (6)

[Claims] (1) The front end of the receiver is equipped with the same number of low-noise amplifiers as the number of diversity branches and a bias voltage generator that generates a bias voltage according to a switching control signal, and the plurality of low-noise amplifiers are controlled by diversity switching. A diversity receiving circuit characterized in that only one low-noise amplifier is operated according to a signal. (2) The receiver front-end low-noise amplifier includes a group of amplifiers of the same number as the number of diversity branches composed of three-terminal active elements, a current control circuit connected to one common terminal of the amplifier group, and an output of the amplifier group. Make the side terminals common,
A resistor element connected to the common terminal, and a bias voltage terminal to which a bias voltage is applied in accordance with a switching control signal, the amplifier being configured to operate only one of the amplifiers in accordance with the switching control signal. 2. The diversity receiving circuit according to claim 1, characterized in that: (3) The diversity receiving circuit according to claim 2, wherein a circuit including a three-terminal active element and a resistor is used as the current control circuit. (4) The diversity receiving circuit according to claim 2, wherein a circuit made of a resistor is used as the current control circuit. (5) The diversity receiving circuit according to any one of claims 2, 3, and 4, characterized in that a bipolar transistor is used as the three-terminal active element. (6) The diversity receiving circuit according to any one of claims 2, 3, and 4, characterized in that a 2-gate FET is used as the 3-terminal active element.