JPH0313106A - Mixer - Google Patents

Abstract

PURPOSE:To reduce the power level of a local oscillation signal (LO signal) and an unnecessary signal to be leaked to an intermediate frequency signal (IF signal) terminal with simple configuration by providing one resonance circuit at least in a low pass filter for IF signal (LPF for IF signal). CONSTITUTION:One resonance circuit 12a or 12b is provided at least between the input/output terminals of an LPF 8 for IF signal. When the resonance frequencies of the resonance circuits (12a and 12b) are set to an LO signal frequency or a spurious signal frequency, a block characteristic is generated between the IF signal terminals from shot key diodes 5a and 5b. Thus, by this block characteristic, the output power level is reduced with the simple configuration for the LO signal or unnecessary spurious signal to be leaked to an IF signal terminal 3.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a mixer that uses the nonlinear characteristics of a Schottky diode to separate a local signal, a high frequency signal, and an intermediate frequency signal, and particularly relates to a mixer that separates a local signal, a high frequency signal, and an intermediate frequency signal. The present invention relates to a technique for reducing the power level of unnecessary signals output to a terminal.

[Conventional technology]

Figure 7 is IEEE MTT-8Digest1983
FIG. 2 is a diagram showing a schematic configuration of a conventional single-type harmonic mixer shown in P130 to P132 in 2010. In the figure, 1 is a high frequency signal (hereinafter abbreviated as RF multiplied signal) terminal, 2 is a local oscillator signal (hereinafter abbreviated as LO signal) terminal, 3 is an intermediate frequency signal (hereinafter abbreviated as IF signal) terminal, and 4 is a terminal for an intermediate frequency signal (hereinafter abbreviated as IF signal). RF signal band pass filter (hereinafter abbreviated as RF signal BPF),
5a and 5b are Schottky diodes (hereinafter abbreviated as SBD), and 6 is an RF signal blocking low-pass filter (hereinafter referred to as SBD).
7 is a high-pass filter for LO signal (hereinafter abbreviated as LO signal HPF), 8 is I
Low-pass filter for F signal (hereinafter abbreviated as LPF for IF signal), 9 is HPF7 for LO signal and LPF8 for IF signal
It is a duplexer consisting of. FIG. 8 is a detailed circuit diagram of the IF signal LPFB, which is composed of an inductor 10 and a capacitor 11.

Next, the mixer configured in this way is adjusted to the RF signal frequency,
A case of operating under the conditions of the LO signal frequency and the IF signal frequency will be described. First, apply the RF multiplied signal frequency (frf) to the RF signal terminal 1 of the harmonic mixer, and at the same time apply the LO
When applying the LO multiplied signal frequency f10) to the signal terminal 2,
At both ends of 5BD5a and 5b, there is a linear frequency component Ou.
A signal with t is generated.

fout = 1m-flo±n-rrfl (m, n are integers)...(1) Now, from among the many frequency components out, in order to efficiently extract the required IF signal frequency fif, Set the frequency characteristics of each filter 4 to 8.

Here, to explain the role of each filter, the RF signal BPF 4 prevents signals other than the LO multiplied signal 1F signal and the RF signal from leaking to the RF signal terminal 1, and Works as a matching circuit for signals. Further, the RF signal blocking LPF 6 prevents the RF multiplied signal from leaking to the LO signal terminal 2 and the IF signal terminal 3. In addition, the LO signal HPF7 outputs the required IF low signal L.
In addition to preventing leakage to the O signal terminal 2, 5BD5
It operates as a matching circuit for LO signals for a and 5b. In addition, the IF signal LOF8 is the LO double signal IF signal terminal 3.
It also serves as a matching circuit for the IF signal to the 5BDs 5a and 5b. The circuit configuration of this IF signal LPF 8 generally consists of an inductor 11 in series and a capacitor 10 in parallel, as shown in FIG.
It has a monotonous attenuation characteristic.

With such a configuration and operation, the required IF low signal can be extracted from the IF signal terminal 3 in the harmonic mixer.

[Problems to be Solved by the Invention] By the way, in the above-mentioned mixer, especially a harmonic mixer, the LO signal frequency flo and the IF signal frequency fif
may be close together. In a mixer with a conventional configuration, the frequency characteristics of the IF signal LPF8 are monotonous, so the LPF 8 has a monotonous frequency characteristic.
There was a problem in that sufficient isolation between the O signal terminal 2 and the IF signal terminal 3 was not achieved, and the O signal leaked to the IF signal terminal 3.

Furthermore, when the IF signal LPFB is multi-staged in order to improve this isolation, there is a problem that the shape becomes large. Furthermore, among the unnecessary spurious signals (frequency fout) that are output simultaneously with the required IF low signal, there is a problem that the spurious signal (frequency fSp) that is close to the IF low signal cannot be sufficiently removed.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a mixer that can reduce the power level of the LO multiplied signal spurious signal leaking to the IF signal terminal with a simple configuration. shall be.

(Means for Solving the Problems) A mixer according to the present invention includes at least one resonant circuit (12a, 12b, or 13a) that resonates at the local oscillation signal and spurious signal frequencies between the input and output terminals of the IF signal LPF (8). , 13b).

[Effect]

In the mixer in this invention, the IF signal LPF (8)
Resonant circuits (12a, 12b) provided inside.

13a, 13b) is set to the LO signal frequency flo or the spurious signal frequency fso, a blocking characteristic occurs between the SBD (5a, 5b) and the IF signal terminal, and this blocking characteristic causes the IF signal terminal (3) to
The output power level of the LO multiplied signal unnecessary signal leaking to the LO multiplied signal is reduced.

(Embodiment) FIG. 1 is a circuit diagram showing an embodiment of the present invention.
The same parts as those in the figures are given the same reference numerals, and the explanation thereof will be omitted.

In Fig. 1, the difference from the conventional one is LPF8 for IF signal.
is configured as shown in FIG. That is,
In Fig. 2, 10a and 10b are inductors, 11a
, 11b, 11c, 11d are capacitors, and 12a
is a first circuit consisting of an inductor 10a and a capacitor 11a.
12b is a second parallel resonant circuit consisting of an inductor 10b and a capacitor 11b.

These parallel resonant circuits 12a and 12b are L for IF signal.
Since it is connected in series between the input and output terminals of PF8, it has blocking characteristics at its resonance frequency.

FIG. 3 is a diagram showing an example of the characteristics of the IF signal LPF 8 in this embodiment. Parallel resonant circuits 12a, 12b
The resonance frequency of each spurious signal frequency f sp
, the local oscillator signal frequency flo results in the characteristics shown by the actual MA. If this characteristic is compared with the characteristic of the conventional configuration shown by the solid line B, a large insertion loss can be obtained at the fsP and flo frequencies.

FIG. 4 shows an example of a spectrum diagram showing the power level of the signal output to the IF signal terminal 3.
(a) is a spectral diagram when an IF signal LPF 8 having a conventional configuration is used, and (b) is a spectral diagram when an IF signal LPF 8 according to the present invention is used. This figure 4 (a>, (b)
As is clear from the figure, it is possible to reduce the power level of the LO signal of frequency flo and the unnecessary d spurious signal of frequency fsp leaking to the F signal terminal 3 without attenuating the required 1F signal.

FIG. 5 is a circuit diagram showing another embodiment of the mixer according to the present invention, and shows a detailed diagram of the IF signal LPF 8. In FIG. 5, 13a is a first series resonant circuit consisting of a capacitor 11a and an inductor 10a, and 13b is a second series resonant circuit consisting of a capacitor 11b and an inductor 10b. These series resonant circuits 13a, 13
b is connected in parallel between the input and output terminals of the IF signal LPF 8, and has a blocking characteristic similar to that of the embodiment shown in FIG. 2 at its resonance frequency. Therefore, the same effect as the first embodiment shown in FIG. 2 is achieved.

FIG. 6 shows still another embodiment of the mixer according to the present invention, and shows a detailed diagram of the IF signal L P F 8. In this embodiment, the IF signal LPF8
A capacitor 11a and an inductor 10 are connected between the input and output terminals of
A parallel resonant circuit 12B consisting of a and a series resonant circuit 1 consisting of a capacitor 11b and an inductor 10b.
3 are connected in parallel, each has a blocking characteristic at each resonant frequency. Therefore, by setting each resonance frequency in the same manner as in the circuit shown in FIG. 2, the same effects as in the embodiment shown in FIG. 2 can be obtained.

In the above embodiment, two blocking frequencies, flo and fsp, are provided, but these are arbitrary, and a resonant circuit may be provided depending on the required blocking frequency.

Further, in the above embodiment, a mixer using two Schottky diodes has been described, but a double-balanced mixer using four Schottky diodes can also produce similar effects.

[Effects of the Invention] As described above, according to the present invention, at least one resonant circuit that resonates at the frequencies of the local oscillation signal and the spurious signal is provided in the IF signal LPF, so that the local oscillation signal leaking to the IF signal terminal is reduced. In addition, the power level of unnecessary signals can be reduced with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a mixer according to an embodiment of the present invention, FIG. 2 is a detailed II [14M diagram] of the LPF for IF signals, and FIG. 3 is a characteristic diagram showing the insertion loss of the LPF for IF signals according to the present invention. , FIG. 4 is a spectrum diagram showing the power level of the signal output to the IF signal terminal of the mixer according to the present invention, FIG. 5 is a diagram showing the configuration of the mixer according to another embodiment of the present invention, and FIG. FIG. 7 is a diagram showing the configuration of a mixer according to still another embodiment of the present invention, FIG. 7 is a diagram showing the configuration of a conventional mixer, and FIG. 8 is a detailed configuration diagram of an IF signal LPF of the conventional mixer. 1...RF signal terminal, 2...LO signal terminal, 3...
・IF signal terminal, 5a, 5b... Schottky diode, 8... LPF for bow F signal, 12a, Go 2 b-
...Parallel resonant circuit, 13a, 13b...Series resonant circuit. In the figures, the same symbols indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] In a mixer comprising a plurality of filter circuits and diodes that separate a local oscillation signal, a high frequency signal, and an intermediate frequency signal, respectively, an input terminal and an output of the filter circuit that extracts the intermediate frequency signal from among the filter circuits. A mixer characterized in that at least one resonant circuit that resonates at a local oscillation signal frequency and a spurious signal frequency is connected between the mixer and the terminal.