JPH10303650A - Frequency converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the frequency converter where leakage of an injected local oscillation(LO) signal is suppressed without using an external filter or the like. SOLUTION: The converter is provided with a 1st power distribution means 2-1 that distributes an LO signal, a 2nd power distribution means 2-2 that distributes an intermediate frequency(IF) signal, a plurality of even number harmonic mixers 1-1, 1-2 that multiply the distributed LO and IF signals, and a power combination means 3 that combines outputs of the even number harmonic mixers 1-1, 1-2 to provide an output of a radio frequency(RF) signal. Then 2n-degree harmonics of the LO signal and the ID signal are mixed while suppressing the injected LO signal through inverted phase combination to provide an output of the RF signal that is frequency-converted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio frequency band frequency converter.

[0002]

2. Description of the Related Art FIG. 10 shows a configuration of a conventional frequency converter using an even harmonic mixer using an anti-parallel diode pair. In the figure, an even harmonic mixer 1 has bidirectionality, a single mixer can share an upconverter and a downconverter, and an injected LO.
There is a feature that even-order harmonics of a signal are not output, and only odd-order harmonics are output.

For example, an even harmonic mixer 1 has an L of 9.7 GHz.
The O signal and the IF signal of 140 MHz are input, and the second harmonic of the LO signal and the IF signal are mixed to make 19.26 GHz and 19.54
When used as an up-converter for obtaining a desired output signal of GHz, since the second harmonic of 19.4 GHz is not output in principle, only the desired output signal can be easily extracted through a filter. That is, even harmonic mixer 1
Has the advantage that it can effectively suppress the second harmonic of the injected LO signal, which is difficult to remove with a filter connected to the subsequent stage because it is close to the desired output signal.

[0004]

However, an even harmonic mixer using an anti-parallel diode pair is not suitable for use in a communication device if the injected LO signal, which is an unnecessary wave at the output terminal, is insufficiently suppressed. There is a problem that the signal error rate increases due to the mixer. This occurs when the leaked injected LO signal is reflected by a filter or an amplifier connected at the subsequent stage and is re-injected from the output terminal. That is,
If the reflection position is far compared to the wavelength of the injected LO signal,
It is considered that even a slight change in the signal frequency occurs because the phase of the reflected wave re-injected into the mixer changes to change the conversion loss.

[0005] If the change in the conversion loss cannot be ignored within the signal band of one communication channel, the signal error rate increases. For example, 20M per communication channel in 20GHz band
When handling high-speed signals of bps or more, the signal bandwidth per channel becomes 20 MHz or more, and when the connection interval between the mixer and the subsequent filter becomes several centimeters, the conversion loss changes within the signal bandwidth and the signal error rate decreases. increase.

Conventionally, in order to prevent the leakage of the injected LO signal, a device such as incorporating a filter such as a band rejection stub into a mixer circuit has been devised. However, the suppression of the injected LO signal by the stub is only about 30 dB. On the other hand, since the amplitude of the injected LO signal is higher than the desired output signal level by 30 dB or more, the injected LO signal having the same output level as the desired output signal leaks at the output end, and the conversion loss in the signal band is reduced. Change was occurring. Therefore, a means for suppressing the injection LO signal leakage of 20 dB or more has been required.

In the frequency converter of FIG. 10, 7 dBm, 9.7 GHz
FIG. 12 shows the results obtained by computer simulation for the output when the LO signal and the IF signal of −5 dBm and 140 MHz were input. Thus, in the conventional frequency converter, the injection LO frequency (9.7 GHz) component is multiplied by the second harmonic of the injection LO signal and the IF signal (19.26 GHz).
(z, 19.54 GHz) component.

In addition, the injection LO signal 2 which is not originally output is
It can be seen that the second harmonic (19.4 GHz) component is also recombined and output with a large amplitude. Therefore, the injection LO signal 2
A narrow band filter has been required for a filter that separates a second harmonic from a desired output signal. SUMMARY OF THE INVENTION An object of the present invention is to provide a frequency converter that can suppress leakage of an injected LO signal without using an external filter or the like.

[0009]

SUMMARY OF THE INVENTION A frequency converter (upconverter) according to the present invention has a first power distribution means for branching an LO signal, a second power distribution means for branching an IF signal, and a second power distribution means. A plurality of even harmonic mixers for multiplying the LO signal and the IF signal; and power combining means for combining the outputs of the respective even harmonic mixers and outputting an RF signal, and suppressing the injected LO signal by combining them in opposite phases. Meanwhile, the 2n-order harmonic of the LO signal is mixed with the IF signal to output an RF signal whose frequency is converted.

A frequency converter (downconverter) according to the present invention comprises a first power distribution means for branching an LO signal;
A second power distribution means for splitting the F signal,
A plurality of even harmonic mixers for multiplying the O signal and the RF signal; and power combining means for combining the outputs of the respective even harmonic mixers and outputting an IF signal, wherein the injected LO signal leaks to the RF signal input terminal. Are mixed in the opposite phase to suppress the 2nd-order harmonic of the LO signal and the RF signal to output an IF signal whose frequency has been converted.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment-Up Converter) FIG. 1 shows a first embodiment of the frequency converter of the present invention. In the figure,
The LO signal is divided into two by a power distribution means 2-1 with a phase difference of 180 degrees and the same amplitude, and is input to even harmonic mixers 1-1 and 1-2 using an anti-parallel diode pair, respectively. On the other hand, the IF signal is divided into two by the power distribution means 2-2 with the same phase and the same amplitude, and each is input to the even harmonic mixers 1-1 and 1-2 each using an anti-parallel diode pair.

The even harmonic mixers 1-1 and 1-2 using an anti-parallel diode pair provide an injection LO frequency component and a multiplication frequency component of a second harmonic of the injection LO signal and an IF signal (desired output signal). , But does not output the second harmonic component of the injected LO signal. Even harmonic mixer 1-1,
The outputs 1-2 are combined by the power combining means 3 with a phase difference of 0 and the same amplitude. At this time, the injected LO frequency components are combined in the opposite phase and attenuated. On the other hand, the second-order harmonic of the injection LO signal branched into two has the same phase, so that the multiplied frequency component (desired output signal) with the IF signal is combined and output in the same phase.

FIG. 11 shows the results obtained by computer simulation of the output when a 7 dBm, 9.7 GHz LO signal and a -5 dBm, 140 MHz IF signal are input to the frequency converter of FIG. As described above, in the frequency converter of the present invention, the injected LO frequency (9.7 GHz) component, which is an unnecessary wave, and the second harmonic (19.4 GHz) component of the injected LO signal are suppressed and hardly output. On the other hand, the injection LO signal 2
Multiplication frequency of the next harmonic and IF signal (19.26 GHz, 19.54
The GHz component is output at a large power level.

(Second Embodiment-Up Converter) FIG. 2 shows a second embodiment of the frequency converter according to the present invention.
The feature of the present embodiment is that, in the first embodiment shown in FIG.
1-2 are directly connected. Note that even if the outputs of the even harmonic mixers 1-1 and 1-2 are directly connected, the injected LO frequency components are combined and attenuated in the opposite phase, and unnecessary wave means can be suppressed. Therefore, there is no need to consider the adverse effect of the leaked injected LO frequency component
The configuration can be simplified.

(Third Embodiment-Up Converter) FIG. 3 shows a third embodiment of the frequency converter according to the present invention.
In the figure, an LO signal is divided into two by an electric power distribution means 2-1 with a phase difference α and the same amplitude, and the even harmonic mixers 1-1, 1--1 each using an anti-parallel diode pair.
2 is input. On the other hand, the IF signal is supplied to the power distribution means 2-
2, an even harmonic mixer 1 using an anti-parallel diode pair.
1, 1-2.

The even harmonic mixers 1-1 and 1-2 using an anti-parallel diode pair provide an injection LO frequency component and a multiplication frequency component of a second harmonic of the injection LO signal and an IF signal (desired output signal). , But does not output the second harmonic component of the injected LO signal. Even harmonic mixer 1-1,
The outputs 1-2 are combined by the power combining means 3 with the phase difference γ and the same amplitude. At this time, if α and γ are set so that the relationship of α + γ = (2m−1) π (m is an integer) is satisfied with respect to the injected LO signal, the injected LO frequency components are combined in opposite phases and attenuated. Thus, the output of unnecessary waves can be suppressed.

On the other hand, although the second harmonic of the two-branched injected LO signal does not have the same phase, the second harmonic of the injected LO signal and the IF signal can be set by appropriately setting the phase difference β between the two branched IF signals. Can be output at a high level. In the first embodiment, α = 180, β = 0, γ in the third embodiment.
= 0.

(Fourth Embodiment-Up Converter) FIG. 4 shows a fourth embodiment of the frequency converter of the present invention.
In the figure, an LO signal is branched into four by a power distribution unit 4-1 and input to even harmonic mixers 1-1 to 1-4 using anti-parallel diode pairs. At this time, assuming that the phase of the LO signal input to the even harmonic mixer 1-1 is 0 degree, the LO signals input to the even harmonic mixers 1-2 to 1-4 are 180 degrees, 45 degrees, and 225 degrees. And the same amplitude.

On the other hand, the IF signal is divided into four by the power distribution means 4-2, and each is inputted to the even harmonic mixers 1-1 to 1-4 using an anti-parallel diode pair. At this time, assuming that the phase of the IF signal input to the even harmonic mixers 1-4 is 0 degree, the IF signals input to the even harmonic mixers 1-1 to 1-3 are 90 + 180 m degrees, 90 + 180 m degrees, and 0 degree. (M is an integer).

The even harmonic mixers 1-1 to 1-4 using an anti-parallel diode pair provide an injection LO frequency component and a multiplication frequency component of a second harmonic of the injection LO signal and an IF signal (desired output signal). , But does not output the second harmonic component of the injected LO signal. Even harmonic mixer 1-1
The outputs 1-4 are combined by the power combining means 5 with a phase difference of 0 and the same amplitude. At this time, the even harmonic mixers 1-1, 1-
2 injection LO frequency components, even harmonic mixers 1-3,1-
The four injected LO frequency components are combined and attenuated in opposite phases. Further, among the multiplied frequency components of the second-order harmonic of the injection LO signal branched into four and the IF signal, one of the multiplied frequency components (desired output signal) and the other image frequency component (unwanted wave) are combined in opposite phases. Being attenuated.

(Fifth Embodiment-Upconverter) FIG. 5 shows a fifth embodiment of the frequency converter according to the present invention.
In the fourth embodiment of the frequency converter shown in FIG.
Although the example in which the second harmonic of the O signal is mixed with the IF signal has been described, the 2nth harmonic of the injected LO signal (n is a natural number)
When mixing the IF signal and the IF signal, the power distribution means 4 converts the injected LO signal into 0, 180, 45 / n, and 180 + 45.
It suffices to branch into four at a phase difference of / n degrees.

(Sixth Embodiment-Up Converter) FIG. 6 shows a sixth embodiment of the frequency converter according to the present invention.
The feature of this embodiment is that the outputs of the even harmonic mixers 1-1 to 1-4 are directly connected instead of the power combining means 5 in the fourth or fifth embodiment shown in FIG. 4 or FIG. It is in. Even if the outputs of the even-harmonic mixers 1-1 to 1-4 are directly connected, the injected LO frequency component and the image frequency component are combined and attenuated in opposite phases, and the unnecessary wave means can be suppressed. Therefore, it is not necessary to consider an adverse effect due to the leakage of the leaked injected LO frequency component, and the configuration can be simplified.

FIG. 7 shows an example of the configuration of the power distribution unit 4. In FIG. 7A, the LO signal is divided into two by the power distribution means 4-1 with a phase difference of 45 / n degrees and the same amplitude.
According to 2,4-3, the signal is split into two with a phase difference of 180 degrees and the same amplitude, and is split into four with a phase difference of 0, 180, 45 / n, and 180 + 45 / n.

In FIG. 7 (2), the LO signal is divided into two by a power distribution means 4-1 with a phase difference of 180 degrees and the same amplitude, and further by the second-stage power distribution means 4-2 and 4-3.
45 / n degree phase difference and two branches with the same amplitude, 0 degree, 180
, 45 / n degrees, and 180 + 45 / n degrees. Note that the power combining means 5 may be similarly configured in a plurality of stages.

(Seventh Embodiment--Down Converter) FIG. 8 shows a seventh embodiment of the frequency converter of the present invention.
In the figure, the LO signal is changed by the power distribution means 2-1 to 1
Even-harmonic mixers 1-1 and 1-1 using an anti-parallel diode pair, each of which is divided into two with an 80 degree phase difference and the same amplitude
1-2. On the other hand, the RF signal is split into two by the power distribution means 2-2 with the same phase and the same amplitude, and the even harmonic mixer 1- 1 using an anti-parallel diode pair is used.
1, 1-2.

The even harmonic mixers 1-1 and 1-2 each using an anti-parallel diode pair provide an injection LO frequency component and a multiplication frequency component of a second harmonic of the injection LO signal and the RF signal (desired output signal). , But does not output the second harmonic component of the injected LO signal. Even harmonic mixer 1-1,
The outputs 1-2 are combined by the power combining means 3 with a phase difference of 0 and the same amplitude. At this time, the injection L leaked to the RF terminal side
O frequency components are combined and attenuated in opposite phases. Therefore, it is possible to avoid the adverse effect of the reflected wave of the injected LO signal due to a filter, an amplifier, or the like connected to the RF terminal.

(Eighth Embodiment) FIG. 9 shows an eighth embodiment of the frequency converter of the present invention. As shown in the first embodiment shown in FIG. 1 and the seventh embodiment shown in FIG.
Even harmonic mixers 1-1 and 1-2 using an anti-parallel diode pair have bidirectionality and can be used for both up-converters and down-converters. Here, as shown in FIG.
-2 and power distributing / combining means 6
1, 6-2, an IF signal is input and RF
The configuration can be adapted to either an up converter that outputs a signal or a down converter that inputs an RF signal and outputs an IF signal.

(Other Embodiments) In each of the embodiments described above, an even harmonic mixer using another non-linear element may be used instead of the even harmonic mixer 1 using an anti-parallel diode pair.

[0029]

As described above, in the frequency converter of the present invention, since the injected LO signals are combined in the opposite phase in the power combining means, they are not output. Therefore, it is possible to improve the deterioration of the signal error rate due to the leakage of the injected LO signal and the reflection at the subsequent stage.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a frequency converter according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the frequency converter according to the present invention.

FIG. 3 is a block diagram showing a third embodiment of the frequency converter according to the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the frequency converter according to the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the frequency converter according to the present invention.

FIG. 6 is a block diagram illustrating a frequency converter according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration example of a power distribution unit 4;

FIG. 8 is a block diagram showing a frequency converter according to a seventh embodiment of the present invention.

FIG. 9 is a block diagram showing an eighth embodiment of the frequency converter according to the present invention.

FIG. 10 is a block diagram showing a configuration of a conventional frequency converter using an even harmonic mixer using an anti-parallel diode pair.

FIG. 11 is a diagram showing an output example of the frequency converter of FIG. 1;

FIG. 12 is a diagram showing an output example of the frequency converter in FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Even harmonic mixer 2, 4 Power distribution means 3, 5 Power synthesis means 6 Power distribution / combination means

Claims (10)

[Claims] 1. A first power distribution means for branching a local signal (hereinafter referred to as “LO signal”) into two with a phase difference of 180 ° and the same amplitude, and an intermediate frequency signal (hereinafter referred to as “IF signal”) in phase and at the same A second power distribution unit that divides into two by amplitude, one LO signal output from the first power distribution unit, and one IF output from the second power distribution unit
A first even harmonic mixer that multiplies and outputs a signal, the other LO signal output from the first power distribution unit, and the other IF signal output from the second power distribution unit
A second even-harmonic mixer that multiplies the signal and outputs the same, and combines the outputs of the first and second even-harmonic mixers with the same phase and the same amplitude to produce a high-frequency signal (hereinafter referred to as an “RF signal”) And a power synthesizing means for outputting a signal. 2. The frequency converter according to claim 1, wherein outputs of the first and second even harmonic mixers are directly connected. 3. A first power distribution unit that divides an LO signal into two with a phase difference α and the same amplitude, a second power distribution unit that divides an IF signal into two with the same amplitude, and the first power distribution unit. And one IF signal output from the second power distribution means.
A first even harmonic mixer that multiplies and outputs a signal, the other LO signal output from the first power distribution unit, and the other IF signal output from the second power distribution unit
A second even harmonic mixer that multiplies and outputs a signal, and a power combining unit that combines the outputs of the first and second even harmonic mixers with a phase difference γ and the same amplitude to output an RF signal Wherein α and γ are set so that the relationship α + γ = (2m−1) π is established with respect to the LO signal (m is an integer). 4. A first power distribution means for branching the LO signal into four with the same amplitude, a second power distribution means for branching the IF signal into four with the same amplitude, and an output from the first power distribution means. 2 of each LO signal
First, second, third, and fourth even harmonic mixers each multiplying and outputting the next harmonic and each IF signal output from the second power distribution means; Power combining means for combining the outputs of the second, third, and fourth even harmonic mixers with the same phase and the same amplitude, and outputting an RF signal, wherein the first power distribution means includes the first even harmonic mixer. Setting the phases of the LO signals input to the second, third, and fourth even harmonic mixers to 180 degrees, 45 degrees, and 225 degrees with respect to the phases of the LO signals input to the wave mixer; The second power distribution unit is configured to control a phase of the IF signal input to the first, second, and third even harmonic mixers with respect to a phase of the IF signal input to the fourth even harmonic mixer. Is set to 90 + 180 m degrees, 90 + 180 m degrees, and 0 degrees (m is an integer). 5. A first power distribution means for dividing the LO signal into four with the same amplitude, a second power distribution means for dividing the IF signal into four with the same amplitude, and output from the first power distribution means. 2 of each LO signal
first, second, third, and fourth even harmonic mixers each multiplying and outputting an nth harmonic (n is a natural number) and each IF signal output from the second power distribution means; Power combining means for combining the outputs of the first, second, third, and fourth even-harmonic mixers with the same phase and the same amplitude, and outputting an RF signal, wherein the first power distribution means comprises: The phase of the LO signal input to the second, third, and fourth even harmonic mixers is 180 degrees, 45 / n degrees with respect to the phase of the LO signal input to the first even harmonic mixer. , 180 + 45 / n degrees, and the second power distribution means sets the first, second, and third even harmonics with respect to the phase of the IF signal input to the fourth even harmonic mixer. The phase of the IF signal input to the wave mixer is set to 90 + 180 m, 90 + 180 m, and 0 (m is an integer). Number converter. 6. The frequency converter according to claim 4, wherein outputs of the first, second, third, and fourth even harmonic mixers are directly connected. Frequency converter. 7. The frequency converter according to claim 4, wherein the power distribution unit has a configuration using a plurality of stages of power distribution units. 8. The frequency converter according to claim 1, wherein the power combining means for outputting the RF signal is replaced with a power distribution means for receiving the RF signal, and the second signal for inputting the IF signal. Wherein the power distribution means is replaced by a power synthesis means for outputting an IF signal. 9. The frequency converter according to claim 1, wherein the second power distribution means for inputting the IF signal is replaced with a power combining / distributing means for inputting or outputting the IF signal. A frequency converter characterized in that the power combining means for outputting an RF signal is replaced with a power distribution / combining means for outputting or inputting an RF signal. 10. The frequency converter according to claim 1, wherein the even harmonic mixer is an even harmonic mixer using an anti-parallel diode pair, or a non-linear element other than the anti-parallel diode pair. A frequency converter characterized in that the frequency converter is an even harmonic mixer using the same.