JPS63306721A - Frequency conversion circuit - Google Patents

Abstract

PURPOSE:To simplify the circuit by directly connecting an output of a distributer and a local oscillation signal input of a frequency mixer and providing an impedance matching circuit between the local oscillator and the distributer so as to use only one impedance matching circuit. CONSTITUTION:At first a local oscillation signal fl outputted from a local oscillator 1 is given to the impedance matching circuit 7 to match the output impedance of the oscillator 1 with the input impedance of the local oscillation signal of frequency mixers 4a, 4b. The local oscillation signal fl subject to impedance conversion is distributed into two by the distributer 2 to supply the signal to the two frequency mixers 4a, 4b and they are fed respectively to the frequency mixers 4a, 4b. As a result, the local oscillation signal is mixed with a high frequency signal fh fed from high frequency signal input terminals 5a, 5b to the frequency mixers 4a, 4b respectively and an intermediate frequency signal fi is obtained at intermediate frequency signal output terminals 6a, 6b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a frequency conversion circuit for a superheterodyne radio receiver, and particularly to a frequency conversion circuit for diversity reception.

(Prior art) In order to reduce the effects of fading, a conventional superheterodyne receiver for diversity reception operates two frequency mixers with the same frequency configuration using a local oscillation signal from one local oscillator. A frequency conversion circuit is configured. FIG. 2 shows a block diagram of the frequency conversion circuit. The frequency conversion circuit in the figure is composed of a local oscillator 1, a divider 2, impedance matching circuits 3a, 3b, frequency mixers 4a, 4b, high frequency signal input terminals 5a, 5b, and intermediate frequency signal output terminals 6a, 6b. .

Next, the operation will be explained.

High frequency signals of the same frequency received from different antennas are input to the high frequency signal input terminals 5a and 5b. A local oscillation signal (fn) output from the local oscillator 1 is divided into two by a distributor 2. The local oscillation signal (b), which is one output of the divider 2, is matched by the impedance matching circuit 3a between the local oscillation signal input impedance of the frequency mixer 4a and the output impedance of the divider.
input to a. As a result, the high frequency signal (fh) and the local oscillation signal (fl) are mixed, and the difference between them is the intermediate frequency signal (
fl) is output from the intermediate frequency signal output terminal 6a. On the other hand, the local oscillation signal (fl) of the other output of the divider 2 is similarly input to the frequency mixer 4b via the impedance matching circuit 3b and mixed with the high frequency signal (fh).
An intermediate frequency signal (f,) is obtained at the intermediate frequency signal output terminal 6b.

(Problem to be Solved by the Invention) However, in the frequency conversion circuit having the above configuration, two impedance matching circuits for the local oscillation signal after dividing the local oscillation wave signal into two are required for each frequency mixer. Therefore, the complexity of the circuit was unavoidable.

An object of the present invention is to solve the above-mentioned problems and provide a frequency conversion circuit with a simplified circuit configuration 2.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a local oscillator that generates a local oscillation signal, a divider that divides the local oscillation signal from the local oscillator into two, and a divider that divides the local oscillation signal from the local oscillator into two parts. a first frequency mixer that mixes the local oscillation signal from the distributor and the first high frequency signal and outputs the first intermediate frequency signal; and a frequency mixer that has the same frequency as the local oscillation signal from the distributor and the first high frequency signal. a second high frequency signal that mixes the second high frequency signal and outputs a second intermediate frequency signal;
In the frequency conversion circuit for a superheterodyne receiver for diversity reception, the frequency converter circuit includes an output impedance of the local oscillator and a local frequency mixer of the first and second frequency mixers between the local oscillator and the distributor. An impedance matching circuit is provided to perform impedance matching with the oscillation signal input impedance.

(Function) According to the present invention, since the frequency conversion circuit is configured as described above, the technical means functions as follows. The impedance matching circuit performs impedance matching for the local oscillation signal from the local oscillator between the output impedance of the local oscillator and the local oscillation signal input impedance of the first and second frequency mixers, and provides an impedance-converted local oscillation signal. to the first and second frequency mixers via the distributor. As a result, in the first and second frequency mixers, the local oscillation signal from the divider and the inputted first and second high frequency signals are frequency mixed, and the first and second intermediate signals are respectively mixed. A frequency signal is output.

In this way, since only one impedance matching circuit is required compared to conventionally two, the circuit configuration of the frequency conversion circuit can be simplified.

(Embodiment) FIG. 1 is a block diagram of a frequency conversion circuit showing an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same components. The difference from FIG. 2 is that the output of the distributor 2 and the local oscillation signal inputs of the frequency mixers 4a and 4b are directly connected, and an impedance matching circuit 7 is provided between the local oscillator 1 and the distributor 2. be.

Next, the operation of this embodiment will be explained.

First, the local oscillation signal (f,
) passes through the impedance matching circuit 7, thereby changing the output impedance of the local oscillator 1 and the frequency mixer 4a,
The local oscillation signal input impedance of 4b can be matched. Next, the impedance-converted local oscillation signal (fl
) is distributed to two frequency mixers 4a and 4b by the distributor 2, and each frequency mixer 4
Added to a, 4b. As a result, local oscillation signals are transmitted from the high frequency signal input terminals 5a and 5b to the frequency mixer 4, respectively.
It is frequency-mixed with the high frequency signal (fh) applied to the signals a and 4b, and an intermediate frequency signal (f+) can be obtained at the intermediate frequency signal output terminals 6a and 6b.

(Effects of the Invention) As described in detail above, according to the present invention, a single local oscillator and an impedance matching circuit that performs impedance matching between the output impedance of the local oscillator and the locally oscillated wave input impedance of the frequency mixer are provided. Since two frequency mixers can be operated by one divider that divides the local oscillation wave into two, the frequency conversion circuit can be expected to be simplified.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a frequency conversion circuit showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional frequency conversion circuit. 1...Local oscillator, 2...Distributor, 4a, 4b---Frequency mixer, 5a, 5b---High frequency signal input terminal, 6a, 6b---
- intermediate frequency signal output terminal, 7... impedance matching circuit.

Claims (1)

[Claims] A local oscillator that generates a local oscillation signal, a divider that divides the local oscillation signal from the local oscillator into two, and a device that mixes the local oscillation signal from the divider and a first high-frequency signal. a first frequency mixer that outputs a first intermediate frequency signal; and a second high frequency signal that mixes the local oscillation signal from the distributor and a second high frequency signal having the same frequency as the first high frequency signal to generate a second intermediate frequency signal. A frequency conversion circuit for a superheterodyne receiver for diversity reception, comprising a second frequency mixer that outputs an output impedance of the local oscillator and a first and second A frequency conversion circuit comprising an impedance matching circuit that performs impedance matching with a local oscillation signal input impedance of a frequency mixer.