JP2003198388A - Transmission harmonic mixer circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a mixer circuit for inhibiting leakage that is an unneeded frequency component in an output signal. <P>SOLUTION: Unneeded frequency components are outputted as leakage from harmonic mixers 206-209 due to the variation of manufacturing of diodes being used for the mixers. Then, signals having a phase difference of 90° each are created from an intermediate frequency one by one by using a first signal creation section 212, and are inputted to the harmonic mixers 206-209. Further, the phases of frequency components to be acquired that are contained in a signal that is outputted from the mixers are set identically by using a second signal creation section 217, and the phases of an unneeded frequency component are set to phases for cancelling out one another for mixing. Therefore, the ratio for amplifying a frequency component to be acquired is set higher than the ratio for amplifying an unneeded frequency component, thus inhibiting leakage that is a relatively unneeded frequency component. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission harmonic mixer circuit, and more particularly to a transmission harmonic mixer circuit that suppresses an output of leak which is an unnecessary frequency component included in an output signal.

[0002]

2. Description of the Related Art A circuit of a communication device that performs radio communication with a radio frequency signal of millimeter waves or microwaves is generally complicated if transmission data such as voice is directly incorporated into the radio frequency signal. Often becomes. Therefore, normally, a communication device that performs wireless communication is designed to modulate the frequency up to the radio frequency after incorporating transmission data into a signal having a frequency lower than the radio frequency, and a mixer is used to perform this modulation. There is. The mixer mixes an intermediate frequency (IF: Intermediate Frequency) signal, which is a signal incorporating input transmission data, and a signal generated by mixing a local oscillation frequency (LO: Local Output frequency) signal with a radio frequency (RF: Radio Frequency). It is designed to be output as a signal. The radio frequency signal output from this mixer is adapted to be used in radio communication, for example. Here, when the frequency of the intermediate frequency signal input to the mixer is f _IF and the frequency of the local oscillation frequency signal is f _LO , the radio frequency signal that outputs the component of frequency f1 shown in the following equation (1) The mixer included in is usually called a Harmonic (Harmonic) mixer.

F1 = 2 × f _LO ± f _IF (1)

FIG. 9 shows an input / output characteristic value of a harmonic mixer (not shown) obtained by an experiment as an example. In the harmonic mixer described above, a pair of diodes connected in parallel in opposite directions is used as the non-linear element. In the figure, the horizontal axis represents the input level of the intermediate frequency (IF) signal input to this harmonic mixer,
The vertical axis represents the output level of the output radio frequency (RF) signal. Although not shown, a local oscillation frequency (LO) signal is input to this harmonic mixer at a constant input level, and the input level is 10 dB.
It is m (Di B M). Here, dBm is a unit of electric power. The curve 111 represents the output level of the frequency component of the frequency f2 represented by the following equation (2) contained in the radio frequency signal with respect to the input level of the intermediate frequency signal.

F2 = 2 × f _LO + f _IF (2)

The above-mentioned harmonic mixer is intended to output the component of frequency f2 expressed by the equation (2). A curve 112 represents the output level of the frequency component of the frequency f3 included in the radio frequency signal with respect to the input level of the intermediate frequency signal and represented by the following equation (3).

F3 = 2 × f _LO (3)

The component of the frequency f3 represented by the equation (3) is an unnecessary frequency component which is caused by the manufacturing variation of the diode used in the harmonic mixer, and is called a leak. In FIG. 9, the leak amount, which is the output level of the frequency component represented by the equation (3), is smaller than 10 dBm which is the input level of the local oscillation frequency signal (not shown), and shows a value of -25 dBm or less.

However, the output level of the frequency component expressed by the equation (3) and the output level of the frequency component expressed by the equation (2) become closer to each other as the input level of the intermediate frequency signal decreases. Therefore, when the input level of the intermediate frequency signal is lowered and used while the input level of the local oscillation frequency signal is kept constant in order to operate the harmonic mixer, the frequency component expressed by the formula (3) is used. The output level of is also a value that cannot be ignored. In FIG. 9, when the input level of the intermediate frequency signal is -15 dBm or less, the output level of the frequency component represented by the equation (3) becomes higher than the output level of the frequency component represented by the equation (2). It often happens. Moreover, since the frequency of the local oscillation frequency signal is usually set to be higher than the frequency of the intermediate frequency signal by one digit or more, the equations (2) and (3) are
The frequency components represented by the equation are easy to approach.
For example, the frequency f _IF of the intermediate frequency signal is 1 MHz (megahertz) and the frequency f _LO of the local oscillation frequency is 10
When the frequency is MHz, the frequency f2 expressed by the equation (2) becomes 21 MHz, which is close to 20 MHz of the frequency f3 expressed by the equation (3). As described above, since these frequencies are close to each other, an increase in the output level of the frequency component represented by the equation (3) causes an increase in noise with respect to the frequency component represented by the equation (2). there were.

However, when the input level of the intermediate frequency signal is lower than the input level of the local oscillation frequency signal, the distortion characteristic of the waveform of the output radio frequency signal is often in a good range. For example, in wireless communication performed between base stations of mobile phones, an operation in a range having a good distortion characteristic is required in order to transfer data at high speed, and an input level of an intermediate frequency signal is set low. In order to deal with such a case, a method of suppressing the leak amount which is the output level of the frequency component represented by the expression (3) has been proposed. As one of them, there is a method of preparing a filter for removing a leak which is a frequency component represented by the equation (3) and suppressing the leak amount by passing an output radio frequency signal through this filter.

However, it is necessary for the filter to have accuracy for distinguishing between the frequencies f2 and f3 expressed by the equation (3) or the equation (2), which causes a problem that the cost for producing the filter becomes high. there were. Also,
Since the filter also lowers the output level of the frequency component represented by the equation (2) that is not the object of removal, there is a problem that a method for compensating for this is required. Therefore,
A circuit has been proposed which reduces the leak, which is the frequency component represented by the equation (3), from the output signal.

FIG. 10 shows an example of a conventional fundamental wave mixer circuit adopting the single balance method. The fundamental wave mixer circuit 121 is provided with a local oscillation frequency (LO) signal input terminal 122, and the local oscillation frequency signal 123 input from this is input to one input side of a hybrid circuit 124. Has become. The other input side of the hybrid circuit 124 is insulated. A signal 125 obtained by advancing the phase of the input local oscillation frequency signal 123 by 180 degrees is output from one output side of the hybrid circuit 124. A signal 126 that does not change the phase of the local oscillation frequency signal 123 is output from the other output side.

An intermediate frequency signal 130 is input from an intermediate frequency (IF) signal input terminal 129 to one input side of the first fundamental wave mixer 127. Similarly, the intermediate frequency signal 130 is input from the intermediate frequency signal input terminal 129 to one input side of the second fundamental wave mixer 128. Also, the first
To the other input side of the fundamental wave mixer 127, the signal 125 output from one output side of the hybrid circuit 124.
Is entered. Further, the signal 126 output from the other output side of the hybrid circuit 124 is input to the other input side of the second fundamental wave mixer 128. From the output side of the first fundamental wave mixer 127, a signal 131 obtained by mixing the intermediate frequency signal 130 and the signal 125 is output. From the output side of the second fundamental wave mixer 128, a signal 132 obtained by mixing the intermediate frequency signal 130 and the signal 126 is output. The signal 131 output from the first fundamental wave mixer 127 is input to one input side of the mixer 133. The signal 132 output from the second fundamental wave mixer 128 is input to the other input side. From the output side of the mixer 133, a signal 134 obtained by mixing the signal 131 and the signal 132 is output. The radio frequency (RF) signal output terminal 135 outputs the signal 134 output from the mixer 133 from the fundamental wave mixer circuit 121.

The leak contained in the signal 131 outputted from the first fundamental wave mixer 127 and the leak contained in the signal 132 outputted from the second fundamental wave mixer 128 of the fundamental wave mixer circuit 121 are The signals 125 and 1 input to the first and second fundamental mixers 127 and 128
According to the phase difference of 26, there is a phase difference of 180 degrees. By mixing these leaks with the mixer 133, the waveforms cancel each other out. That is,
The amount of leak contained in the signal 134 output from the fundamental wave mixer circuit 121 is reduced.

The frequency of the leak contained in the signal output from the above harmonic mixer and expressed by the equation (3) is such that the frequency of the local oscillation frequency signal is doubled. Therefore, this fundamental wave mixer circuit 12
Two fundamental mixers 127 and 1 provided in
When 28 are replaced with the above-mentioned harmonic mixers, the phase difference of the leak waveforms output from each becomes 360 degrees, which is twice 180 degrees. That is, the waveforms of the two leaks match, and even if they are mixed, they cannot cancel each other. Therefore, even if the two fundamental wave mixers 127 and 128 of the conventional fundamental wave mixer circuit 121 adopting the single balance method are replaced with the above-mentioned harmonic mixers, the leakage cannot be reduced.

Further, Japanese Patent Laid-Open No. 2001-308647 proposes a mixer circuit which reduces leakage by suppressing a difference in current and voltage characteristics due to variations in diodes used in a harmonic mixer. This mixer circuit includes a detector that detects the current and voltage characteristics of a diode used in the harmonic mixer, and a power supply that applies a voltage to the harmonic mixer. This detector detects variations in the current and voltage characteristics of the diodes used in the harmonic mixer. By applying a voltage based on this detection result to the harmonic mixer by the power supply, variations in the current and voltage characteristics of the diode are eliminated and leakage is prevented.

[0017]

However, in this mixer circuit, the above-mentioned detection device for detecting the current and voltage characteristics of the diode and the power supply for applying the voltage to the harmonic mixer are required, which complicates the structure of the device. There was a problem of becoming.

Therefore, an object of the present invention is to provide a harmonic mixer circuit which has a simple structure and reduces the ratio of leakage which is a specific unnecessary frequency component from an output signal.

[0019]

According to a first aspect of the invention, (a) a first signal for transmitting a first signal containing a first frequency component incorporating transmission data which is data to be transmitted. Transmitting means and (b) second signal transmitting means for transmitting a second signal containing a component of the second frequency; and (c)
First signal generating means for generating one signal having the same amplitude with four types of phase differences different by 90 degrees from each other with the first signal transmitted from the first signal transmitting means as a base point of the phase;
(D) A third signal obtained by mixing each of the four types of signals created by the first signal creating means and the second signal and adding a frequency obtained by doubling the second frequency to the first frequency. A harmonic mixer that generates four types of signals containing frequency components, and (e) a first type corresponding to these signals from the four types of signals that are generated by this harmonic mixer.
By mixing the signals created by the second signal creating means with the second signal creating means provided by the signal creating means for creating the corresponding four types of signals with the phase differences eliminated, respectively. The transmission harmonic mixer circuit is provided with signal output means for outputting a single signal obtained by amplifying the third frequency component.

That is, according to the first aspect of the invention, the first signal transmitting means of the transmission harmonic mixer circuit transmits a first signal containing a first frequency component in which transmission data such as voice is incorporated. It is supposed to do.
Here, the first frequency may be a frequency that facilitates incorporation of transmission data. The second signal transmitting means is adapted to transmit a second signal containing a component of the second frequency. The first signal creating means uses the phase of the first signal as a base point,
The signals of equal amplitude are created one by one by shifting the phase of the first signal by 90 degrees. In other words, focusing only on the phase difference, the phase of the first signal is set as
4 with phase differences of 90, 180, and 270 degrees
It is designed to create one signal. The harmonic mixer is adapted to create four kinds of signals by mixing each of the four signals created by the first signal creating means and the second signal. Further, the frequency components of these created signals include at least a third frequency component obtained by adding a frequency obtained by doubling the second frequency to the first frequency. This means that when each of the signals created by the first signal creating means and the second signal are mixed, the created signal contains components of a plurality of types of frequencies. The frequency component of is also included. The harmonic mixer may be provided for each of the four signals created by the first signal creating means. The second signal producing means eliminates the phase difference between the four signals produced by these harmonic mixers.
It is designed to create one signal. For example, if there is a phase difference of 0 degree, 90 degrees, 180 degrees, or 270 degrees with respect to the phase of any signal output from the harmonic mixer, the phase of the signal having the phase of 0 degree is By advancing by 90 degrees and returning the phase of a signal having a phase of 180 degrees by 90 degrees, by returning the phase of a signal having a phase of 270 degrees by 180 degrees, a signal having a phase of 90 degrees can be obtained.
The phases of the two signals can be aligned. Here, the second
Although the example of matching the phase of the other signal to the phase of any of the signals received by the signal creating means has been described, the phase of the four signals may be aligned to the phase that does not correspond to any of these signals. . The signal output means outputs one signal in which the signal of the third frequency is amplified by mixing the signals created by the second signal creating means.

In such a transmission harmonic mixer circuit, when the first signal and the second signal are mixed, for example, a component having a frequency that is twice the second frequency is output from the harmonic mixer as a leak 4 It is included in one signal. Since these frequency components depend only on the second frequency, there is no phase difference between the frequency components that are twice the second frequency contained in each of the four signals. The amount of leak, which is the output of these frequency components, is the magnitude of noise with respect to the third frequency component. The four signals output from each harmonic mixer have their phases changed by the second signal creating means so as to eliminate the phase difference given to the signal created by the first signal creating means based on the first signal. It has become so. That is, four kinds of phase differences differing by 90 degrees are given to the component of the frequency obtained by doubling the second frequency by the second signal creating means, and there is a phase difference of 180 degrees among them. The ingredients will cancel each other out. Further, since the signal of the third frequency mixes four signals having no phase difference, the signals are amplified without canceling each other. Therefore, it is possible to reduce the ratio of the output of the frequency component obtained by doubling the second frequency included in the signal output from the transmission harmonic mixer circuit to reduce the leak amount relatively to the component of the third frequency. You can Further, the transmission harmonic mixer circuit of the present invention does not require a signal input or a device to be used only to suppress the leak amount, so that the configuration of the device can be simplified.

According to the second aspect of the invention, (a) a first signal transmitting means for transmitting a first signal containing a first frequency component incorporating transmission data which is data to be transmitted, and (b) ) Second signal transmission means for transmitting a second signal containing a second frequency component, and (c) 90 degrees each with the first signal transmitted from the first signal transmission means as the base point of the phase. A first signal creating means for creating signals of the same amplitude one by one with four different phase differences; and (d) four signals respectively created by the first signal creating means and a second signal. And a third frequency component obtained by adding the first frequency to the frequency obtained by doubling the second frequency, and the second frequency
A harmonic mixer that creates four signals including a fourth frequency component obtained by subtracting the first frequency from the frequency obtained by doubling the frequency of 4 and a fifth frequency component obtained by doubling the second frequency. (E) From the four signals created by this harmonic mixer, the second signal creation for creating the corresponding four signals respectively corresponding to these signals by eliminating the phase difference provided by the first signal creating means Means and
(F) The transmission harmonic mixer circuit is provided with a signal output unit that mixes the signals generated by the second signal generation unit and outputs the mixed signal as a single signal in which the third frequency component is amplified.

That is, according to the second aspect of the invention, the first signal transmitting means of the transmission harmonic mixer circuit transmits the first signal containing the first frequency component in which transmission data such as voice is incorporated. It is supposed to do.
Here, the first frequency may be a frequency that facilitates incorporation of transmission data. The second signal transmitting means is adapted to transmit a second signal containing a component of the second frequency. The first signal creating means uses the phase of the first signal as a base point,
The signals of equal amplitude are created one by one by shifting the phase of the first signal by 90 degrees. In other words, focusing only on the phase difference, the phase of the first signal is set as
4 with phase differences of 90, 180, and 270 degrees
It is designed to create one signal. The harmonic mixer is adapted to create four kinds of signals by mixing each of the four signals created by the first signal creating means and the second signal. In addition, a frequency component having a third frequency obtained by adding the first frequency to a frequency obtained by doubling the second frequency and a frequency obtained by doubling the second frequency And a frequency component having a fifth frequency obtained by doubling the second frequency are included. The harmonic mixer may be provided for each of the four signals created by the first signal creating means. Second
The signal creating means of (4) creates four signals in which the phase difference between the four signals created by these harmonic mixers is eliminated. For example, 0 degree from the phase of one of the signals output from the harmonic mixer as a base point,
When there is a phase difference of 90 degrees, 180 degrees, or 270 degrees in each signal, the phase of the signal having the phase of 0 degree is
By advancing by 0 degree, the phase of a signal having a phase of 180 degrees is returned by 90 degrees, and the phase of a signal having a phase of 270 degree is returned by 180 degrees, thereby aligning the phases of four signals with a signal having a phase of 90 degrees. be able to. Here, an example is shown in which the phases of the other signals are matched with the phases of the signals received by the second signal generating means, but the phases of the four signals are matched with the phases that do not correspond to any of these signals. May be The signal output means mixes the signals created by the second signal creation means to output one signal containing the third frequency component.

In such a transmission harmonic mixer circuit, the fourth and fifth frequency components are included in the four signals output from the respective harmonic mixers. The component of the fourth frequency is the phase difference given to the signal created by the first signal creating means based on the first signal when subtracting the first frequency from the frequency obtained by doubling the second frequency. The components will be given in the opposite direction. Further, the second signal creating means eliminates the phase difference given to the signal created by the first signal creating means based on the first signal,
When the phases of the four signals output from the harmonic mixer are changed, the fourth frequency component has a direction opposite to that given by the first signal creating means to the signal created based on the first signal. A double phase difference will occur. That is, 18
Four kinds of phase differences different from each other by 0 degree are given, and components having a phase difference of 180 degrees cancel each other out. Further, since the component of the fifth frequency depends only on the second frequency, there is no phase difference between these components included in each of the four signals output from the harmonic mixer. In the second signal creating means, the first signal creating means is the first
The phases of these four signals are changed so as to eliminate the phase difference given to the signals created on the basis of the above signals. In other words, the fifth signal component is provided with four types of phase differences that differ by 90 degrees by the second signal creating means, and components having a phase difference of 180 degrees among them are canceled out. It fits. Further, since the four signals having no phase difference are mixed by the signal output means with respect to the third frequency component, all the frequency components are added and amplified. Therefore, the ratio of the output of the fourth and fifth frequency components included in the signal output from the transmission harmonic mixer circuit can be relatively reduced with respect to the third frequency component. In addition, the transmission harmonic mixer circuit of the present invention does not require an input signal or a device to be used only for reducing the outputs of the components of the fourth and fifth frequencies, so that the configuration of the device is simplified. can do.

According to a third aspect of the present invention, in the transmission harmonic mixer circuit according to the first or second aspect, the third frequency is a predetermined radio frequency for transmitting the transmission data. There is.

That is, the invention of claim 3 is characterized in that the third frequency is a predetermined radio frequency for transmitting the transmission data. Therefore, when such a transmission harmonic mixer circuit is installed between, for example, base stations that perform wireless communication, a low-frequency signal incorporating transmission data is modulated into a predetermined radio-frequency signal for wireless transmission. Can be used for

According to a fourth aspect of the invention, in the transmission harmonic mixer circuit according to the second aspect, the output of the fifth frequency component contained in at least one of the four signals generated by the harmonic mixer is the other output. It is characterized in that it is different from the output of the fifth frequency component contained in the three signals.

That is, the invention according to claim 4 indicates that the output of the fifth frequency component contained in each of the four signals generated by the harmonic mixer is different in at least one or all the signals. Even in such a case, the fifth frequency components included in the four signals cancel each other out when mixed by the signal output means described in claim 3, and therefore, the third frequency component is described. It is possible to suppress the ratio of amplification more than the third frequency component.

According to a fifth aspect of the present invention, in the transmission harmonic mixer circuit according to the first or second aspect, the harmonic mixer is four circuits each including a pair of reversely connected diodes as nonlinear elements. It is characterized by being configured.

That is, in the invention described in claim 5, the harmonic mixer provided in the transmission harmonic mixer circuit can be configured by four circuits each including a pair of diodes connected in parallel in opposite directions as a nonlinear element.

[0031]

DETAILED DESCRIPTION OF THE INVENTION

[0032]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows a circuit configuration of a mixer circuit according to an embodiment of the present invention. Mixer circuit 201
Contains the intermediate frequency (IF: In
termediate frequency) signal 202 to mixer circuit 201
An intermediate frequency signal input terminal 203 for inputting to the radio frequency signal output terminal 205 for outputting a radio frequency (RF: Radio Frequency) signal 204 including a component of a frequency predetermined for communication from the mixer circuit 201. It is equipped. Further, the first to fourth harmonic mixers 206 to 209 and a local oscillation frequency signal input terminal 211 for inputting a local oscillation frequency (LO: Local Output frequency) signal 210 including a component of a frequency common to them.
Is provided. The intermediate frequency signal 202 input from the intermediate frequency signal input terminal 203 is frequency-modulated by the first to fourth harmonic mixers 206 to 209, and is output as the radio frequency signal 204 from the mixer circuit 201 via the radio frequency signal output terminal 205. It is supposed to be output. Further, the first circuit provided in the mixer circuit 201
Of the intermediate frequency signal input terminal 203.
The four signals 213 to 216 created from the intermediate frequency signal 202 input from the are output. In addition, the second signal creation unit 2 included in the mixer circuit 201
17 is the first to fourth harmonic mixers 206 to 20
The signals 218 to 221 respectively output from the 9 are input, and the radio frequency signal 204 is created from these signals and output. The first signal creation unit 212 and the second signal creation unit 217 will be described in detail later. In this mixer circuit 201, when the signals output from the first to fourth harmonic mixers 206 to 209 are mixed, the frequency components used for data transmission included in these signals are higher than unnecessary frequency components. Then, it is designed to amplify.

The first to fourth harmonic mixers 206 to
209 corresponds to the corresponding first input terminals 222 to 222.
225, second input terminals 226 to 229, and output terminals 230 to 233 are provided one by one. The corresponding first input terminals 222 to 225 provided on the harmonic mixers 206 to 209 respectively include:
The local oscillation frequency signal 210 is input from the local oscillation frequency signal input terminal 211. The second input terminal 226 of the first harmonic mixer 206
The signal 21 output from the first signal generator 212.
3 is input. In addition, the first harmonic mixer 20
The output terminal 230 of 6 outputs a signal 218 which is a mixture of the input local oscillation frequency signal 210 and the signal 213. Second harmonic mixer 20
7 to the second input terminal 227, the first signal generation unit 21
The signal 214 output from 2 is input. Also, the second
From the output terminal 231 of the harmonic mixer 207 of
A signal 219 obtained by mixing the input local oscillation frequency signal 210 and signal 214 is output.

The signal 215 output from the first signal generator 212 is input to the second input terminal 228 of the third harmonic mixer 208. The output terminal 232 of the third harmonic mixer 208 outputs a signal 220 which is a mixture of the input local oscillation frequency signal 210 and signal 215. The signal 216 output from the first signal creation unit 212 is input to the second input terminal 229 of the fourth harmonic mixer 209. A signal 221 obtained by mixing the input local oscillation frequency signal 210 and the signal 216 is output from the output terminal 233 of the fourth harmonic mixer 209.

Such a mixer circuit 201 is provided in, for example, a base station that transmits and receives data to and from a mobile terminal. Between such base stations, the mixer circuit 201 is used to generate a radio frequency signal 204 from a signal incorporating data such as voice as the intermediate frequency signal 202, and the radio frequency signal 204 is used for radio communication.

FIG. 2 shows the inside of the first signal creating section in detail. Inside the first signal creation unit 212, first to third hybrid circuits 241 to 243 are provided. The first hybrid circuit 241 has two input terminals 244 and 245 and two output terminals 246.
And 247 are provided. The first input terminal 244
The intermediate frequency signal 202 is input from the intermediate frequency signal input terminal 203. The second input terminal 245 is an insulation terminal. The first hybrid circuit 241 is adapted to generate two types of signals from the input intermediate frequency signal 202, a signal obtained by advancing the phase of this signal by 180 degrees and a signal that does not change the phase. These two types of signals are created as signals of equal power. First output terminal 2 of first hybrid circuit 241
A signal 248 that does not change the phase is output from 46.
A signal 249 with a phase advanced by 180 degrees is output from the second output terminal 247.

The second hybrid circuit 242 has two input terminals 250 and 251 and two output terminals 252 and 253. Second hybrid circuit 24
Signal 2 output from the first output terminal 246 of the first hybrid circuit 241.
48 is input. The second input terminal 251 is an insulating terminal. The second hybrid circuit 242 is
From the input signal 248, two types of signals are created, a signal that is 90 degrees ahead of the phase of this signal and a signal that does not change the phase. These two types of signals are created as signals of equal power. Second hybrid circuit 242
Signal 2 which does not change the phase from the first output terminal 252 of
13 is output. The second output terminal 253 outputs the signal 214 with the phase advanced by 90 degrees.

The third hybrid circuit 243 has two input terminals 254 and 255 and two output terminals 256 and 257. Third hybrid circuit 24
Signal 2 output from the second output terminal 247 of the first hybrid circuit 241.
49 is input. The second input terminal 255 is an insulating terminal. The third hybrid circuit 243 is
From the input signal 249, two types of signals are generated, a signal which is 90 degrees ahead of the phase of this signal and a signal whose phase is not changed. These two types of signals are created as signals of equal power. Third hybrid circuit 243
The signal 2 which does not change the phase from the first output terminal 256 of
15 is output. Further, a signal 216 whose phase is advanced by 90 degrees is output from the second output terminal 257. Thus, the four output terminals 252, 253 of the second and third hybrid circuits 242 and 243,
From 256 and 257, respectively, the intermediate frequency signal 2
With respect to 02, four signals 213 to 216 having a phase difference of 0 degree, 90 degrees, 180 degrees and 270 degrees are output.

FIG. 3 shows the inside of the second signal creating section in detail. Inside the second signal creation unit 217, fourth to sixth hybrid circuits 261 to 263 are provided. The fourth hybrid circuit 261 has 2
Two input terminals 264 and 265 and two output terminals 26
6 and 267 are provided. The signal 218 output from the output terminal 230 of the first harmonic mixer 206 is input to the first input terminal 264 of the fourth hybrid circuit 261. The second input terminal 265 has an output terminal 231 of the second harmonic mixer 207.
The signal 219 output from is input. From the first output terminal 266 of the fourth hybrid circuit 261, the first
The phase of the signal 218 input from the input terminal 264 of
A signal 268 obtained by mixing the signal advanced by 0 degree and the signal 219 input from the second input terminal 265 is output. The second output terminal 267 is an insulating terminal.

The fifth hybrid circuit 262 has two input terminals 269 and 270 and two output terminals 271.
And 272 are provided. The signal 220 output from the output terminal 232 of the third harmonic mixer 208 is input to the first input terminal 269 of the fifth hybrid circuit 262. The second input terminal 270 has
The signal 221 output from the output terminal 233 of the fourth harmonic mixer 209 is input. From the first output terminal 271 of the fifth hybrid circuit 262, a signal obtained by advancing the phase of the signal 220 input from the first input terminal 269 by 90 degrees and a signal 221 input from the second input terminal 270. A signal 273 obtained by mixing and is output. The second output terminal 272 is an insulating terminal.

The sixth hybrid circuit 263 has two input terminals 274 and 275 and two output terminals 276.
And 277 are provided. The signal 268 output from the first output terminal 266 of the fourth hybrid circuit 261 is input to the first input terminal 274 of the sixth hybrid circuit 263. Further, the second input terminal 275 has a first output terminal 2 of the fifth hybrid circuit 262.
The signal 273 output from 71 is input. From the first output terminal 276 of the sixth hybrid circuit 263,
The radio frequency signal 204 obtained by mixing the signal 268 input from the first input terminal 274 and the signal 273 input from the second input terminal 275 with the phase advanced by 180 degrees.
Is output. The second output terminal 2
Reference numeral 77 is an insulating terminal.

Next, signals input / output in the mixer circuit 201 of this embodiment will be described. The first signal generation unit 21 is connected to the first to fourth harmonic mixers 206 to 209.
The corresponding signals 213 to 216 are input from each of the two. When the frequency of the intermediate frequency signal 202 is represented by the code f _IF , the waveform I of the signals 213 to 216
F1 to IF4 are respectively expressed by the following equations (4) to (7).

[0044] _{IF1 = φsin (2πf IF) ......} (4) IF2 = φsin (2πf IF + 90 °) ...... (5) IF3 = φsin (2πf IF + 180 °) ...... (6) IF4 = φsin (2πf IF +270 °) …… (7)

Here, π is the circular constant, and φ is the waveforms IF1 to I.
The amplitude of F4 is shown. In this way, the waveforms IF1 to IF4 have a phase of a sine wave of equal amplitude of 0 degrees and 90 degrees.
The waveform is advanced by 180 degrees and 180 degrees and 270 degrees.
Further, the first to fourth harmonic mixers 206 to 209
A common local oscillation frequency signal 210 is input to the. When the frequency of the local oscillation frequency signal 210 is represented by f _LO , the waveform LO1 of the local oscillation frequency signal 210 is expressed by the following equation (9).

LO1 = μsin (2πf _LO ) (9)

Here, μ represents the amplitude of the waveform LO1. Further, according to the principle of the harmonic mixer, the frequency f4 included in the output signal output from each mixer is expressed by the following equation (10). The method of deriving the expression (10) will be described in detail later.

F4 = f _LO × 2 ± f _IF (10)

As a result, the signals 218 output from the first to fourth harmonic mixers 206 to 209, respectively.
221 waveforms RF1 to RF4 are expressed by the following equation (11).
These are respectively expressed by equation (14).

[0050] RF1 = αsin {2π (f_LO× 2 + f_IF)} + Αsin {2π (f_LO× 2-f _IF )} …… (11) RF2 = αsin {2π (f_LO× 2 + f_IF) + 90 °} + αsin {2π (f_LO × 2-f_IF) -90 °} (12) RF3 = αsin {2π (f_LO× 2 + f_IF) + 180 °} + αsin {2π (f _LO × 2-f_IF) -180 °} (13) RF4 = αsin {2π (f_LO× 2 + f_IF) + 270 °} + αsin {2π (f _LO × 2-f_IF) -270 °} (14)

Here, α represents half the amplitude of the waveforms RF1 to RF4. The signals 218 and 219 output from the first and second harmonic mixers are combined by the fourth hybrid circuit 261 of the second signal creating unit 217 with a phase difference of 90 degrees.
The waveform RF5 of the signal 268 output from the fourth hybrid circuit 261 is expressed by the following expression (15) from the expressions (11) and (12).

RF5 = α sin {2π (f _LO × 2 + f _IF ) + 90 °} + α sin {2π (f _LO × 2-f _IF ) + 90 °} + α sin {2π (f _LO × 2 + f _IF ) + 90 °} + αs in {2π (F _LO × 2-f _IF ) −90 °} (15)

The first and second terms of equation (15) are (1
The phase of the waveform RF1 of the output signal 218 from the first harmonic mixer 206 expressed by the equation (1) is advanced by 90 degrees. The third and fourth terms are the waveform RF2 itself of the output signal 219 from the second harmonic mixer 207 expressed by the equation (12). Here, since the sum of the second term and the fourth term is “0”, the equation (15) is
It is expressed by the following equation (16).

RF5 = 2αsin {2π (f _LO × 2 + f _IF ) + 90 °} (16)

Similarly, the fifth hybrid circuit 262 of the second signal generator 217 outputs the signals 220 and 221 input from the third and fourth harmonic mixers 208 and 209 with a phase difference of 90 degrees. The waveform RF6 of the signal 273 that is output after being combined with each other is expressed by the following equation (17).

RF6 = 2αsin {2π (f _LO × 2 + f _IF ) + 270 °} (17)

The sixth hybrid circuit 2 of the second signal generator 217 to which these signals 268 and 273 are input.
63 couples these with a phase difference of 180 degrees and outputs as a radio frequency signal 204. At this time, the waveform RF7 of the radio frequency signal 204 is expressed by the following expression (18) from the expressions (16) and (17).

RF7 = 2αsin {2π (f _LO × 2 + f _IF ) + 90 °} + 2α sin {2π (f _LO × 2 + f _IF ) + 270 ° + 180 °} (18)

The first term and the second term of the equation (18) are sine waves having the same amplitude and frequency, and since they have a phase difference of 360 degrees, it is equal to the fact that there is no phase difference. Therefore, the equation (18) can also be expressed by the following equation (19).

RF7 = 4αsin {2π (f _LO × 2 + f _IF ) + 90 °} (19)

From the above description, regarding the signals output from the first to fourth harmonic mixers 206 to 209,
From the frequency component represented by the equation (10), the following (20)
It can be seen that only the component of the frequency f5 represented by the formula is combined and amplified four times. That is, the components of the frequency f6 represented by the following equation (21) can be canceled out. The frequency f6 is generally called the image frequency of the frequency f5. Therefore, the mixer circuit 201 can be used as an image suppression type mixer circuit.

F5 = f _LO × 2 + f _IF (20) f6 = f _LO × 2-f _IF (21)

Now, the first to fourth harmonic mixers 2
In the ideal calculation, only the odd-order frequency components 06 to 209 are output as signals, but actually, the frequency f7 component represented by the following equation (22) is also output. It is known.

F7 = f _LO × 2 (22)

With respect to the signal having the frequency component represented by the equation (22), finally the mixer circuit 2 of the present embodiment.
Let's calculate what kind of output appears as 01. First, the first to fourth harmonic mixers 206 to 2
Since the signal 210 input to the 09 is a signal having the same phase and the same amplitude, the frequencies appearing in the output signal are also equal and are represented by the equation (22). Therefore, the first
The waveforms RF11 of the signals output from the fourth harmonic mixers 206 to 209 are equally represented by the following equation (23).

RF11 = βsin {2π (f _LO × 2)} (23)

Here, the amplitude β of the output signal is from the first to the first.
The signals output from the fourth harmonic mixers 206 to 209 are common. When two such signals are input to the fourth hybrid circuit 261, they are combined with a phase difference of 90 degrees and output. Waveform RF of this output signal
12 is represented by the following equation (24).

RF12 = βsin {2π (f _LO × 2)} + βsin {2π (f _LO × 2) + 90 °} (24)

The signal expressed by the equation (23) is the fifth signal.
When the two hybrid circuits 262 are input, they are combined with a phase difference of 90 degrees and output as in the case of the fourth hybrid circuit 261. The waveform RF13 of the output signal is expressed by the following equation (25).

RF13 = βsin {2π (f _LO × 2)} + βsin {2π (f _LO × 2) + 90 °} (25)

Then, these fourth hybrid circuit 2
61 and the signals output from the fifth hybrid circuit 262 are input to the sixth hybrid circuit 263, and 1
The signals are combined and output with a phase difference of 80 degrees. The waveform RF1 of the signal output from the sixth hybrid circuit 263
4 is represented by the following equation (26).

RF14 = βsin {2π (f _LO × 2)} + βsin {2π (f _LO × 2) + 90 °} + βsin {2π (f _LO × 2) + 180 °} + βsin {2π (f _LO × 2) + 270 ° } (26)

The first term and the third term and the second term and the fourth term of the equation (26) are sine waves having the same amplitude and frequency with a phase difference of 180 degrees, and they cancel each other. ing. Therefore, the equation (26) can also be expressed by the following equation (27).

RF14 = 0 (27)

Therefore, the components having the frequency expressed by the equation (22) cancel each other out and do not appear as a component in the output signal of the mixer circuit 201 of this embodiment.

As described above, by using the mixer circuit 201 of the present embodiment, the leak which is the image frequency component represented by the equation (21) and the leakage which is the frequency component represented by the equation (22) are eliminated. At the same time, the effect of suppressing can be obtained.

Next, the first to fourth harmonic mixers 2
It will be described in detail that a signal having a frequency component represented by the equation (10) is output as the output signals of 06 to 209. First, an example of the configuration of the harmonic mixer and an example of the characteristics of the voltage V and the current I of the harmonic mixer will be described.

FIG. 4 shows an example of the configuration of the harmonic mixer used in the mixer circuit. In the harmonic mixer 311, a pair of diodes 312 and 313 connected in parallel in opposite directions is arranged as a non-linear element. Input signals of two different frequencies from the terminal 314 to the harmonic mixer 311 and
When 15 is grounded, a harmonic signal can be taken out from the harmonic mixer 311.

FIG. 5 shows an example of the characteristics of the voltage V and the current I of the harmonic mixer shown in FIG.
The characteristics of the voltage V and the current I of the harmonic mixer 311 are
It is non-linear as shown by the curve 321 shown in the figure, and is a series of points represented by the following equation (28).

I = I ₀ × {[exp (Vq / kT) -1]-[exp (-Vq / kT) -1]} (28)

Here, I is the current flowing through the harmonic mixer, I ₀ is the diode saturation current, V is the voltage, q is the electron charge, k is the Boltzmann constant, and T is the absolute temperature. This equation (28) can be expressed by the following equation (29) by decomposing the natural logarithm using the Maclaurin expansion.

[0082] I = I₀× {(2q / kT) V + (q³/ 3k³T³) V³+ (Q^Five/ 60k^FiveT^Five) V ^Five +…} …… (29)

As described above, assuming that the electron charge q, the Boltzmann constant k, and the absolute temperature T are constants, the current I flowing through the harmonic mixer is a polynomial consisting of odd-order terms depending on the voltage V (29). It is expressed as. The voltage depending on the frequency represented by the frequency f _LO of the local oscillation frequency signal and the frequency f _IF of the intermediate frequency signal is substituted into V of the equation (29). Here, the following (3
Substitute the voltage Vin represented by the equation (0).

Vin = Asin (2πf _LO t) + Bsin (2πf _IF t) (30)

The waveform of the voltage Vin is the amplitude A of the local oscillation frequency signal input to the harmonic mixer and the amplitude B of the intermediate frequency signal input to the harmonic mixer, the time t, the frequency f _LO and the intermediate frequency of the local oscillation frequency signal. It depends on the frequency f _IF of the signal and is expressed as in equation (30). The following expression (31) is obtained when the voltage Vin represented by the expression (30) is input to the cubic term of the expression (29).
This is a representation of the frequency components of the signal output from the harmonic mixer. Here we know the result 1
The description of the following terms and the terms of the 5th order and thereafter where the coefficient is small will be omitted. Further, the amplitude A of the local oscillation frequency signal is assumed to be sufficiently larger than the amplitude B of the intermediate frequency signal, and the terms where the square and the cube of the amplitude B are coefficients are:
This is omitted because the value becomes smaller. Further, the coefficient of the value V ³ of the third-order term in the equation (29) is a constant, and only the value of V ³ is calculated here.

V ³ = −A ³ / 4sin (2π3f _LO t) −3A ² B / 4sin {2π (2f _LO + f _IF ) t} + 3AB ² / 4sin {2π (2f _LO −f _IF ) t} + 3A ³ / 4sin (2π3f _LO t) + 3A ² B / 2sin (2π3f _IF t) (31)

From the second and third terms of the equation (31), it is understood that the harmonic frequency components as in the equation (10) described above are extracted as the output signal of the harmonic mixer. Further, as can be seen from the equation (31), originally, the harmonic mixer has already been described (2
It can be seen that the frequency components of even-order harmonics as in the equation (2) cannot be extracted.

Next, a case will be described in which there is a difference in the leak amount from each of the harmonic mixers 206 to 209 used in the mixer circuit 201.

The first to fourth harmonic mixers 206 to 2 used in the mixer circuit 201 (FIG. 1) of this embodiment.
The amount of leak generated from 09 (the same figure) was assumed to be the same, as expressed by the common expression of the amplitude β in the equation (23) already described. However, in actual harmonic mixers, the difference in current and voltage characteristics is caused by the dispersion of the diodes as already explained, so the current and voltage characteristics of each harmonic mixer used in the same mixer circuit are completely different. Not necessarily the same.

FIG. 6 shows how the leak amounts output from the first to fourth harmonic mixers described above are combined. In the figure, vectors 401-
Reference numerals 404 denote the first to fourth harmonic mixers 20, respectively.
6 shows a state after the leak amounts output from 6 to 209 have a phase difference of 90 degrees each by the fourth to sixth hybrid circuits 261 to 263. Vector 40
1 and vector 403 exist on the straight line in opposite directions,
The vector 402 and the vector 404 exist on the straight line in opposite directions. These two straight lines are orthogonal. Also,
The values of the vectors 401 to 404 are the same value because the amplitude β expressed by the equation (22) is the same value. Therefore, it can be seen that these vectors cancel each other when they are combined, and become a vector of value "0" (not shown), so that the leak amount does not exist.

FIG. 7 shows a state in which the first to fourth harmonic mixers are combined when the leak amounts output from the harmonic mixers are different from each other. In the figure, the leak amounts output from the first to fourth harmonic mixers 206 to 209 are represented by corresponding vectors 411 to 414 each having a phase difference of 90 degrees. Here, the case where the amplitude β represented by the equation (22) has different values is shown, and when the vectors 411 to 414 are combined, the vector 415 which is not the value “0” appears. As described above, when the values of the leak amounts from the respective harmonic mixers are different from each other, the leak amounts are not completely offset, and the signal output from the mixer circuit 201 has a leak amount having the value of the vector 415 as an output level. Will appear.

FIG. 8 shows how the leak amounts output from the first to fourth harmonic mixers are combined when the leak amounts have certain values. In this figure, the first and second harmonic mixers 206
The leak amounts generated only from 207 and 207 are represented as corresponding vectors 421 and 422 having a phase difference of 90 degrees. Here, the value of the vector 423 generated by combining the vectors 421 and 422 is the vector 42.
If 1 and 422 have the same value, then these 1.4
This is a doubled value, which means that the leak amount is amplified more than the original value. However, as shown in equation (19),
Since the frequency component you want to extract is amplified four times,
Compared with this, the ratio of the leak amount to the output signal is reduced. Therefore, the ratio of the amount of leak contained in the output signal from the mixer circuit 201 can be reduced regardless of the amount of leak of the harmonic mixer alone.

Since the leak can be completely offset or at least reduced in this way, the filter provided in the mixer circuit 201 for reducing the leak can be simplified or omitted.

The mixer circuit 201 (FIG. 1) of this embodiment is as described above.
Is used, it is possible to suppress the frequency component of the image frequency represented by the equation (21) included in the output radio frequency signal 204. Further, as already described, the frequency component of the leak expressed by the equation (22) can be suppressed.

Possibility of modification of the invention

In the present embodiment described above, the first to third hybrid circuits 241 to 243 are used to give a phase difference to the intermediate frequency signal 202. However, as described above, if the circuit inputs the signals of equal power obtained by adding the phase difference of 90 degrees to the intermediate frequency signal 202 to the first to fourth harmonic mixers 206 to 209, respectively.
You may replace with these 1st-3rd hybrid circuits 241-243. The fourth to sixth hybrid circuits 261 to 26 that change the phases of the signals output from the first to fourth harmonic mixers 206 to 209, respectively.
The same may be applied to 3 as well.

[0097]

As described above, according to the invention of claim 1 or 2, the harmonic mixer is
A signal including the component of the third frequency is output, and the components of the third frequency have a phase difference of 90 degrees, but these phase differences are eliminated and then mixed so that they are amplified. Has become. Therefore, the transmission harmonic mixer according to these inventions can be used as an amplifier circuit for the third frequency component.

According to the third aspect of the invention, the third frequency is a predetermined frequency for transmitting the transmission data by radio communication. Therefore, the transmission harmonic mixer circuit of the present invention mixes the signals having the components of the first frequency and the second frequency different from the third frequency, and outputs the signal of the predetermined radio frequency which is the third frequency. A signal with components can be obtained.

Further, according to the invention of claim 4, at least one of the components of the fifth frequency contained in each of the four signals outputted from the harmonic mixer is at least the other three components.
Different from one. Even when the outputs of the components of the fifth frequency are not aligned in this way, these four components still cancel each other out, and therefore, the components of the fifth frequency of the fifth frequency included in the signal output from the transmission harmonic mixer circuit remain unchanged. The proportion of ingredients can be reduced.

Further, according to the fifth aspect of the invention, the harmonic mixer of the present invention can be constructed by using four circuits each including a pair of diodes connected in parallel in opposite directions as the non-linear element. By thus configuring the harmonic mixer by distributing it to four circuits, it is possible to increase the degree of freedom in arranging the circuits as compared with configuring the harmonic mixer with one circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a mixer circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing in detail a first signal creation unit.

FIG. 3 is a block diagram showing in detail a second signal generation unit.

FIG. 4 is a block diagram showing an example of a non-linear element used in a harmonic mixer.

5 is an explanatory diagram illustrating an example of voltage and current characteristics of the non-linear element shown in FIG.

FIG. 6 is an explanatory diagram illustrating a leak output from the mixer circuit when the output levels of the leak output from the harmonic mixer used in the mixer circuit of the present embodiment are all the same.

FIG. 7 is an explanatory diagram illustrating a leak output from the mixer circuit when the output levels of the leak output from the harmonic mixers used in the mixer circuit of the present embodiment are different from each other.

FIG. 8 is an explanatory diagram illustrating a leak output from the mixer circuit when the output level of the leak output from the harmonic mixer used in the mixer circuit according to the present embodiment has a certain value.

FIG. 9 is an explanatory diagram illustrating output level characteristics of some frequency components included in a radio frequency signal output with respect to an input level of an input intermediate frequency signal, as an example of experimental values of a harmonic mixer. .

FIG. 10 is a block diagram showing a conventional fundamental wave mixer circuit that cancels leakage by a single balance method.

[Explanation of symbols]

201 mixer circuit 202 Intermediate frequency (IF) signal 203 Intermediate frequency (IF) signal input terminal 204 Radio Frequency (RF) Signal 205 Radio frequency (RF) signal output terminal 206 First Harmonic Mixer 207 Second Harmonic Mixer 208 Third Harmonic Mixer 209 Fourth Harmonic Mixer 210 Local oscillator frequency (LO) signal 211 Local oscillation frequency (LO) signal input terminal 212 First Signal Generation Unit 217 Second signal creation unit 241 First hybrid circuit 242 Second hybrid circuit 243 Third hybrid circuit 261 Fourth Hybrid Circuit 262 Fifth Hybrid Circuit 263 Sixth Hybrid Circuit

Claims (5)

[Claims] 1. A first signal transmitting means for transmitting a first signal including a first frequency component incorporating transmission data which is data to be transmitted, and a second signal transmitting means including a second frequency component. Second to send the signal of
And a signal generating means for generating one signal having the same amplitude with four kinds of phase differences differing by 90 degrees from each other with the first signal transmitted from the first signal transmitting means as a base point of the phase. And a frequency obtained by doubling the second frequency to the first frequency by mixing each of the four types of signals generated by the first signal generation means with the second signal. And a harmonic mixer for generating four types of signals including a third frequency component, and the first signal generating means corresponding to these signals from the four types of signals generated by the harmonic mixer. The second signal producing means for producing four types of corresponding signals that have eliminated the generated phase difference and the signal produced by the second signal producing means are mixed to amplify the third frequency component. One done And a signal output means for outputting the signal as a signal of the transmission harmonic mixer circuit. 2. A first signal transmission means for transmitting a first signal containing a first frequency component incorporating transmission data which is data to be transmitted, and a second signal transmission means containing a second frequency component. Second to send the signal of
And a signal generating means for generating one signal having the same amplitude with four kinds of phase differences differing by 90 degrees from each other with the first signal transmitted from the first signal transmitting means as a base point of the phase. Signal mixing means, the four signals created by the first signal creating means, and the second signal are mixed, and the first frequency is set to a frequency obtained by doubling the second frequency. A third frequency component added, a fourth frequency component obtained by subtracting the first frequency from a frequency obtained by doubling the second frequency, and a fifth frequency obtained by doubling the second frequency. And a phase difference provided by the first signal generating means corresponding to these signals from the four signals generated by the harmonic mixer. Correspond A second signal generating means for generating one signal and a signal output means for mixing the signals generated by the second signal generating means and outputting the amplified signal as a single signal of the third frequency component. A transmission harmonic mixer circuit comprising. 3. The transmission harmonic mixer circuit according to claim 1 or 2, wherein the third frequency is a predetermined radio frequency for transmitting the transmission data. 4. The output of the fifth frequency component contained in at least one of the four signals produced by the harmonic mixer is different from the output of the fifth frequency component contained in the other three signals. The transmission harmonic mixer circuit according to claim 2. 5. The transmission harmonic according to claim 1, wherein the harmonic mixer is composed of four circuits each including a pair of diodes connected in reverse as parallel as a non-linear element. Mixer circuit.