JPS62235808A - Frequency converting circuit - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution by using one FET to apply two operations such as frequency multiplication and frequency conversion. CONSTITUTION:After a local oscillation signal is divided into two by signals having a phase difference of 90 deg. by a 90 deg. distributer 5, they are doubled by field effect transistors (TRs) 6,7, then a two multiple signal having a phase difference by 180 deg. is obtained but it is not ideally outputted because being cancelled by an in-phase synthesizer 9. The input signals, however, are fed to the field effect TRs by a phase difference of 180 deg., and when they are mixed by double-frequency signals having a phase difference of 180 deg., the in-phase frequency conversion signal is obtained and combined in phase by an in-phase synthesizer 9 and the result is outputted. That is, since the frequency multiplication and the frequency conversion are applied by the field effect TRs 6,7, the circuit constitution is simplified.

Description

[Detailed Description of the Invention] [Summary] In a frequency conversion circuit, a local oscillation signal with a phase difference of 90 degrees is input to the gates of two field effect transistors whose sources are grounded, and a signal multiplied by two weeks appears at the drain of each field effect transistor. A frequency-converted signal obtained by mixing a double signal and an input signal having a 180 degree phase difference injected into two drains is synthesized in phase and extracted, thereby simplifying the circuit configuration.

This suppresses leakage of the local optical rX signal.

[Industrial Application Field] The present invention relates to an improvement in a frequency conversion circuit used, for example, in an up-converter of a microwave band transmitter.

Advances in semiconductor technology have led to the development of field effect transistors (hereinafter abbreviated as FETs) that operate in ultra-high frequency bands, which can now be used as frequency conversion elements in ultra-high frequency bands instead of diodes for ultra-high frequency bands. Therefore,
There is a need for a frequency conversion circuit that uses this FET, has a simple circuit configuration, and suppresses leakage of local oscillation signals.

[Conventional technology]

FIG. 3 shows a block diagram of a conventional example.

In the figure, 1 is a rough trace type hybrid, and this hybrid has the following properties. That is, (1) The power of the signal applied to terminal ■ is divided in half and appears at terminals ■ and ■ with a phase difference of 180 degrees,
It does not appear on terminal ■.

(2) Signals input from terminal ■ and terminal ■ are combined in phase at terminal ■, but do not appear at terminal ■.

Next, the local oscillation signal of, for example, 6.5 GHz inputted from the terminal lN-1 is multiplied by 2 weeks by the 2-week multiplier 4 and becomes 13 Gtlz.
After being converted into a signal of rough trace type hybrid l
The signal is applied from the terminal (2) through the terminal (2) and the terminal (2) to the diodes 2 and 3, which are connected in opposite directions to each other, with a phase difference of 180 degrees.

On the other hand, the intermediate frequency signal of, for example, I GHz, which should be converted into two frequencies, is also applied to diodes 2 and 3, so 614G)lz
, 12 GHz, etc., are in-phase synthesized and output from terminal (2). Therefore, only the desired 14 GHz component is extracted using a band pass filter (not shown).

Note that since a rough trace type hybrid is used, ideally the local oscillation signal does not appear on the output side as described above, but in reality it leaks to some extent. However, since the leakage power is small, the configuration of the band-pass filter for extracting the desired frequency-converted signal is relatively simple.

However, the reason why the 13 GHz directly oscillated local oscillation signal is not input to the rough trace type hybrid is that when a local oscillation signal with high frequency stability is required, the configuration of the frequency stabilization circuit is easier when the oscillation frequency is lower. It is for the sake of becoming.

[Problem that the invention seeks to solve]

However, as explained above, since a two-week multiplier is required separately, there is a problem that the circuit configuration of the frequency conversion circuit becomes complicated.

[Means for solving problems]

The above problem is as shown in Figure 1, when the local oscillation signal is
90 degree divider 5 that divides into two signals with a phase difference of degrees
, a 180 degree divider 8 which divides the input signal into two signals having a phase difference of 180 degrees, and the outputs of the 90 degree divider are added to the respective gates to generate 2i! A source-grounded field effect transistor 6 that mixes the 1-multiplied signal that appears at each drain and the output of the 180-degree divider 8 that is injected into each drain to obtain a frequency-converted signal. .7, and an in-phase synthesizer 9 that combines the respective drain outputs of the field effect transistors in the same phase.

[Effect]

In the present invention, a local oscillation signal is divided into two signals with a phase difference of 90 degrees by a 90 degree divider 5, and then doubled by each field effect transistor 6.7 to obtain a doubled signal with a phase difference of 180 degrees. However, if this happens, ideally it will be canceled by the in-phase synthesizer 9 and not output.

However, the input signal is applied to the field effect transistor with a phase difference of 180 degrees, and when mixed here with the above-mentioned double signal with a phase difference of 180 degrees, an in-phase frequency converted signal is obtained, and the in-phase synthesizer 9, the signals are in-phase combined and output. That is, since the field effect transistors 6 and 7 perform frequency multiplication and frequency conversion, the circuit configuration becomes simple.

〔Example〕

FIG. 2 shows a block diagram of an embodiment of the invention.

In addition, the same symbols indicate the same objects throughout the figures, 61,
71 is an input side matching circuit, 62 and 72 are output side matching circuits, and C1 and C2 are DC blocking capacitors.

Hereinafter, the operation will be explained with reference to FIG. 2 assuming that the input and output frequencies are the same as in the conventional example.

In the figure, a 6.5 GHz local oscillation signal is divided into two signals with a 90 degree phase difference by a 90 degree hybrid (hereinafter abbreviated as 90 degree 11YB), and then sent to the source via an input side matching circuit 61. Gate (G) of field effect transistor (hereinafter abbreviated as PET) 6 with (S) grounded
added to. Therefore, due to the rectification effect on the gate side of the PE 76 and the nonlinearity of the mutual conductance gm, a signal of 13 GHz, which is doubled, appears at the drain (D).

On the other hand, the l GHz input signal is 180 degrees HYB 8 and 1
After being divided into two signals with a phase difference of 80 degrees, one signal is applied to the drain of PH76 and amplitude modulated by the drain resistance between the drain and source of FET 6 varying at 13 GHz to 12 GH2 and 14 GH2. Frequency-converted signals such as , etc. appear on the drain side. Therefore, 14
A frequency conversion signal such as GHz is applied to the in-phase synthesizer 9 via an output matching circuit 62 and a DC blocking capacitor C1.

In addition, the same operation as above is performed for FET 7 to obtain 14G.
The frequency converted signal of Hz is applied to the in-phase synthesizer 9 and F
It is in-phase combined with that generated by ET 6 and fed to a neutral power, but the circuit configuration is simplified because the frequency is multiplied by 9 and converted using FET.

Furthermore, leakage of the local oscillation signal is suppressed by the in-phase synthesizer 9 as described above.

〔Effect of the invention〕

As explained in detail above, according to the present invention, one FET
Since the two operations of frequency multiplication and frequency conversion are performed, the effect of simplifying the circuit configuration can be obtained.

Note that since the leakage of the local oscillation signal is suppressed, the configuration of the filter for extracting the desired signal is simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional example. In the figure, 5 is a 90 degree divider, 6.7 is a field effect transistor, 8 is a 180 degree divider, and 9 is an in-phase combiner.

Claims (1)

[Claims] A 90 degree divider (5) that divides a local oscillation signal into two signals with a phase difference of 90 degrees, and a 180 degree divider (5) that divides an input signal into two signals with a phase difference of 180 degrees. The outputs of the divider (8) and the 90-degree divider are applied to the respective gates and multiplied by 2, and the doubled signals appear at the respective drains, and the outputs of the 180-degree divider (8) are injected into the respective drains. ), and a common-source field effect transistor (6, 7) that mixes the outputs of the field-effect transistors to obtain a frequency-converted signal, and an in-phase synthesizer (9) that combines the drain outputs of the field-effect transistors in the same phase. A frequency conversion circuit characterized by: