JPH0526809Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a single-end mixer used, for example, in a satellite broadcasting receiver.

[Technical background of the invention] Satellite broadcasting receivers are generally equipped with so-called single-balance mixers or single-end mixers that are constructed using transmission lines called microstrip lines. Single-end mixers are often used because of their small size and cost. By the way, such conventional single-ended mixers do not interfere with each other at the input and output ends of the input signal, local oscillation (LO) signal, and converted intermediate (IF) frequency signal, and can transmit and receive signals with high efficiency. To make this possible, bandpass filters, open stubs, short stubs, low-pass filters, etc. are arranged on the transmission line as shown in FIG.

That is, the single-ended mixer shown in FIG. 4 has a bandpass filter 3 connected to one end of a diode 1, which has the input signal connected to the signal input end 2 as a passband, and a bandpass filter 3 that has a passband of the input signal connected to the signal input terminal 2, and a stopband that includes the LO signal and the converted IF signal. An open stub 4 and a short stub 5 are provided to efficiently input an input signal to the other end of the diode 1.
Moreover, an open stub 7 for preventing leakage to the IF signal output terminal 6 and an unnecessary signal blocking filter, such as a low-pass filter 8, are provided. The main line 9 connected to the open stub 7 has a connecting portion 1.
A bandpass filter 12 having a pass band for the LO signal and connected to the LO signal input terminal 11 is disposed in the coupling section 10 .

[Problems with the background art] However, the single-end mixer described above has the following problems:
Since the band-pass filter 3, open stub 4, short stub 5, low-pass filter 8, and band-pass filter 12 are configured in combination, so-called ripples occur in the frequency characteristics of the conversion loss, and the frequency There was a problem that the characteristics deteriorated. For this reason, attempts have been made to install correction circuits or reduce the number of filters, stubs, etc. in order to obtain the desired frequency characteristics, but none of these have been achieved through manufacturing, including design. However, it is very complicated and requires a correction circuit, which results in a large size.

[Purpose of the invention] This invention was created in view of the above circumstances.
It is an object of the present invention to provide a single-end mixer that has a simple configuration, can improve frequency characteristics as much as possible, and can be made as compact as possible.

[Summary of the invention] In other words, this invention connects an open stub with a line length of approximately 1/4 wavelength for the input signal to the other end of a diode that is connected to a high-frequency signal input circuit at one end, and connects this open stub to the other end of the diode. The device is configured to reliably prevent the input signal from leaking to the local oscillation signal input terminal by being shared as the final stage of a bandpass filter that allows the local oscillation signal to pass, achieving the intended purpose. It is.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.

FIG. 1 shows a single-end mixer according to an embodiment of this invention, and 20 in the figure is a signal input terminal. This signal input terminal 20 is provided with a bandpass filter 2 for passing the input signal and for blocking the LO signal, the IF signal after frequency conversion, and the signal in the image frequency band.
One end of 1 is connected. At the other end of this bandpass filter 21, there is an open stub 22 for preventing LO signal leakage, which has a 1/4 wavelength with respect to the LO frequency.
and has a line length of approximately 1/4 wavelength for the input signal,
One end of a frequency conversion diode 24 is connected via a short stub 23 for preventing IF signal leakage, which has a high impedance with respect to the input signal and a low impedance with respect to the IF signal. At the other end of this diode 24, there is approximately 1/4 of the input signal frequency.
An open stub 25 having a line length of the same wavelength is connected to the base of the open stub 25, and an IF signal output end 27 is connected to the base of the open stub 25 via a low-pass filter 26 for blocking unnecessary high frequencies. Further, a band-pass filter 28 for passing the LO signal is coupled to the open stub 25 in a high frequency manner so as to constitute the final stage of the band-pass filter 28. The end is connected to the LO signal input end 29.
The present invention is characterized in that the open stub 25 itself constitutes the final stage of the bandpass filter 28.

In the above configuration, the input signal is input to the signal input terminal 20.
, a bandpass filter 21, an open stub 22,
It is input to the diode 24 via the short stub 23. On the other hand, the LO signal is input from the LO signal input terminal 29 to the diode 24 via the bandpass filter 28 which also uses the open stub 25 as the final stage. Here, since the impedance of the diode 24 with respect to the input signal at the connection part with the open stub 25 is stable in a substantially short state, the diode 24 mixes the input signal and the LO signal with high performance, and absorbs the difference. IF, which is a frequency signal
The signal is outputted to an IF signal output terminal 27 via a low-pass filter 26.

In this way, the above single-ended mixer is LO
Since the final stage of the bandpass filter 28 for signal passing is made to share the open stub 25 connected to the diode 24 as a component, the impedance at the connection between the diode 24 and the open stub 25 with respect to the input signal frequency is reduced. is stabilized to a substantially short state, and the adverse effects of the input signal reflected by the bandpass filter are prevented, making fabrication as easy as possible. Furthermore, by sharing the open stub 25 as a component of the bandpass filter 28, the components can be simplified and downsized, and leakage of the LO signal to the signal input terminal 20 can be prevented. definitely prevented,
Frequency characteristics are also improved.

In addition, this invention is not limited to the above embodiments,
For example, as shown in FIG.
a, open stub 22a, short stub 23
a. Changing the shape of all the components of the bandpass filter 28a and the lowpass filter 26a that share the open stub 25a, or change the shape of all the component parts of the bandpass filter 28a and the lowpass filter 26a that share the open stub 25b, as shown in FIG. Wave device 2
It is also possible to change only the shape of 8b and configure it to be applied to a case where the LO frequency is lower than the input signal frequency, so substantially the same effect can be expected in either case.

[Effects of the invention] As detailed above, according to this invention, it is possible to improve the frequency characteristics as much as possible with a simple configuration, and to realize miniaturization as much as possible. It is possible to provide a single-ended mixer.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing a single-end mixer according to one embodiment of this invention, and FIGS. 2 and 3 are construction diagrams showing other embodiments of this invention, respectively.
FIG. 4 is a block diagram showing a conventional single-end mixer. 20... Signal input end, 21, 21a... Band pass filter, 22, 22a... Open stub, 2
3, 23a... Short stub, 24... Diode, 25, 25a, 25b... Open stub, 26, 26a... Low pass filter, 27...
IF signal output terminal, 28, 28a, 28b...Band pass filter, 29...LO signal input terminal.

Claims (1)

[Claims for Utility Model Registration] One end is connected to a high frequency signal input circuit, and the other end is connected to an open stub having a line length of approximately 1/4 wavelength for the high frequency input signal obtained from the high frequency signal input circuit. a bandpass filter that shares the open stub as a final stage to pass a local oscillation signal; and a bandpass filter that connects the diode of the open stub that forms the final stage of the bandpass filter. A single-ended mixer comprising an intermediate frequency signal output circuit having an input end connected to an end thereof.