JP2005244681A - Mixer circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the conversion of signal frequency band while a prescribed frequency band is attenuated. <P>SOLUTION: Diodes D1-D4 are arranged in ring with their contact points being node N1 to node N4. An RF input terminal is connected to the node N1 and the node N3 through a first transformer 50, and local signal 204 is inputted to the middle point of a second winding 58 of the first transformer 50. An IF output terminal is connected to the node N2 and the node N4 through a second transformer 54 with the middle point of a first winding 60 of the second transformer 54 being grounded. Further, between the node N1 and the node N4 as well as between the node N2 and the node N3, band reject filters F1 and F2 are provided which represent the same attenuation characteristics at a specified frequency band. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a frequency conversion technique, and more particularly to a mixer circuit (frequency conversion circuit) that converts a frequency between two frequencies and a radio apparatus using the mixer circuit.

  A general wireless communication apparatus includes an amplifier that amplifies a signal input to and output from an antenna, a balun that converts an unbalanced signal and a balanced signal of the antenna, and a mixer that performs frequency conversion between a radio frequency and a frequency for modulation and demodulation. And a function such as a PLL for generating a local signal for sending a mixer switch signal. In ordinary wireless communication devices, it is common to install various filters between each component function to prevent interference and leakage with unnecessary frequency bands. On the other hand, the radio frequency is increasing, and this is dealt with by increasing the transistor speed by miniaturizing the device process. However, since the breakdown voltage decreases when the process is miniaturized, it is necessary to reduce the operating voltage of the transistor.

As described above, the wireless communication device has a plurality of communication function circuits such as an amplifier, a balun, and a mixer. Here, the mixer will be described. Mixers that perform frequency conversion by high-frequency wireless communication are roughly classified into active mixers and passive mixers. The passive mixer uses a diode or the like as a passive element to convert the frequency, so that loss is caused by the conversion, but it does not depend on the power supply voltage and does not consume power. On the other hand, a mixer that changes the cutoff frequency has also been proposed (see, for example, Patent Document 1).
JP 2003-298355 A

  Due to the recent development of communication systems, cases where adjacent frequency bands are used in different communication systems are increasing, and there are cases where a plurality of communication systems are built in the same portable terminal. Therefore, it becomes necessary to remove interference from adjacent frequency bands, and the filter configuration in the system tends to be complicated. Further, in a communication method using a wideband frequency, for example, UWB (ultra-wideband communication), there is a case where a prohibited band is included in the band. On the other hand, for the manufacturer of the wireless communication device, if the unnecessary signal can be removed, the mixer can be applied to various wireless communication systems, and therefore the versatility of the mixer is increased.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a mixer circuit (frequency conversion circuit) capable of effectively reducing interference in a predetermined frequency band while converting the frequency, and a radio apparatus using the mixer circuit. Is to provide.

One embodiment of the present invention is a mixer circuit (frequency conversion circuit). The circuit includes a first input unit that inputs a signal to be processed, a second input unit that inputs a reference signal for converting the frequency of the input signal to be processed, and an input based on the input reference signal. A conversion unit that converts the frequency of the signal to be processed, and an output unit that outputs the signal to be processed whose frequency is converted. In this circuit, the conversion unit forms a bridge with a plurality of passively used elements, and a band elimination filter is arranged between nodes of the plurality of passively used elements, and is output from the output unit. The signal to be processed whose frequency is converted may be attenuated in a predetermined frequency band by a band elimination filter.
“A band elimination filter is arranged between nodes of a plurality of passively used elements” may be “a band elimination filter is arranged in parallel with any of a plurality of passively used elements”.

  With the above circuit, the band elimination filter is arranged in parallel with any of the plurality of passively used elements that constitute the bridge. Therefore, unnecessary frequency components are converted according to the characteristics of the band elimination filter while converting the frequency. Can be attenuated.

The conversion unit has a primary winding and a secondary winding, one end of the primary winding is connected to the first input unit, and the midpoint of the secondary winding is connected to the second input unit. Between the four diodes as a plurality of passively used elements that form bridges connected to both ends of the first transformer and the secondary winding of the first transformer, and between the nodes of the four diodes. Apart from the connected band elimination filter and the first transformer, it has a primary winding and a secondary winding, and both ends of the primary winding are connected to four diodes, respectively, and the secondary winding A second transformer having one end of the first diode connected to the output unit, two non-adjacent contacts of the four contacts of the four diodes are respectively connected to both ends of the secondary winding of the first transformer, The remaining two of the four contacts are the primary that the second transformer has. It may be connected to both ends of the line.
The “band elimination filter connected between the nodes of the four diodes” may be “a band elimination filter connected in parallel to any one of the four diodes”.

The first input unit includes two terminals for inputting a signal to be processed that configures a differential signal, and the second input unit includes two terminals for inputting a reference signal that configures the differential signal. The output unit includes two terminals for outputting a signal to be processed that constitutes a differential signal, and the conversion unit includes 4 as a plurality of passively used elements that constitute a bridge. Two non-adjacent contacts among the four contacts of the four transistors are respectively connected to the two terminals of the first input unit, including a band elimination filter connected between one transistor and a node of the four transistors, The remaining two contacts of the four contacts are respectively connected to the two terminals of the output unit, and are included in two non-adjacent transistors of the four transistors, and Among the transistors, a terminal not connected to the bridge is connected to one of the two terminals of the second input unit, and is included in the remaining two transistors among the four transistors, and A terminal that is not connected to the bridge may be connected to the other of the two terminals of the second input unit.
The “band elimination filter connected between the nodes of the four transistors” may be “a band elimination filter connected in parallel to any of the four transistors”.

  The band elimination filter arranged in the conversion unit may further include a terminal that can vary the center frequency and sets the center frequency of the band elimination filter from the outside. Two or more band elimination filters may be arranged in the conversion unit. Two or more band elimination filters arranged in the conversion unit may be defined such that the center frequencies are substantially the same. At least one of the two or more band elimination filters arranged in the conversion unit may be defined such that the center frequency is different from the other band elimination filters.

  Another aspect of the present invention is a wireless device. This device includes a radio unit that processes a radio frequency signal, a radio frequency signal, a frequency conversion unit that converts a frequency between intermediate frequency signals lower than the radio frequency, an intermediate frequency signal, and an intermediate frequency And a processing unit for processing a low baseband signal. In this apparatus, the frequency conversion unit includes a first input unit that inputs one of a radio frequency signal and an intermediate frequency signal as a signal to be processed, and a reference for converting the frequency of the input signal to be processed. A second input unit that inputs a signal, a conversion unit that converts the frequency of the input signal to be processed based on the input reference signal, a signal to be processed that has been converted in frequency, a radio frequency signal, and an intermediate frequency signal An output unit that outputs the other of the signals, and the conversion unit forms a bridge with a plurality of passively used elements, and a band elimination filter between nodes of the passively used elements The processing target signal obtained by converting the frequency output from the output unit may be attenuated in a predetermined frequency band by a band elimination filter.

  ADVANTAGE OF THE INVENTION According to this invention, the mixer circuit (frequency conversion circuit) which can reduce effectively the interference of a predetermined frequency band, converting a frequency, and a radio | wireless apparatus using the same can be provided.

(Example 1)
Before describing the present invention in detail, an outline will be described. Embodiment 1 of the present invention relates to a wireless device used in a wireless communication system such as a simplified mobile phone system or a third generation mobile phone system, and particularly between a radio frequency (RF) and an intermediate frequency (IF). The present invention relates to a frequency conversion circuit that converts the frequency of a transmission signal and a reception signal, that is, a mixer circuit. The mixer circuit according to the present embodiment is configured based on a passive mixer circuit, and a band elimination filter is disposed in parallel with a predetermined diode among the diode bridges included in the passive mixer circuit. . As a result, it is possible to attenuate the signal intensity of a predetermined band while converting the frequency of the signal.

  FIG. 1 shows a configuration of a radio apparatus 100 according to Embodiment 1 of the present invention. The wireless device 100 includes an antenna 10, a wireless unit 12, a processing unit 14, an interface unit 16, and a control unit 70. The radio unit 12 includes a switching unit 18, an LNA 20, a first frequency conversion unit 22, an HPA 24, a second frequency conversion unit 26, and an oscillator 28, and the processing unit 14 includes an orthogonal detection unit 30, an AGC 32, and an AD conversion unit 34. , A demodulator 36, an orthogonal modulator 38, a DA converter 40, and a modulator 42. The signal includes an RF signal 200, an IF signal 202, and a local signal 204.

  The antenna 10 transmits or receives a signal via a wireless propagation path. The switching unit 18 switches between the transmission side and the reception side when the communication system uses TDD as in the simple cellular phone system. That is, when radio apparatus 100 operates as a transmission side, a signal input from antenna 10 is output to LNA 20, while when radio apparatus 100 operates as a reception side, a signal input from HPA 24 is output to antenna 10. The LNA 20 amplifies the received signal and outputs an RF signal 200. The oscillator 28 outputs a local signal 204 having a predetermined frequency. The first frequency conversion unit 22 performs frequency conversion on the RF signal 200 based on the local signal 204, here down-converts, and outputs the IF signal 202. The quadrature detection unit 30 performs quadrature detection on the IF signal 202. In addition, since the signal detected by quadrature detection generally includes an in-phase component and a quadrature component, the number of arrows in the figure corresponding to the signal output from the quadrature detection unit 30 should be two. It will be omitted and indicated by a single arrow.

The AGC 32 adjusts the amplitude of the quadrature detected signal so as to approach a predetermined value. The AD converter 34 performs analog-digital conversion on the signal output from the AGC 32 and outputs a digital signal. The demodulator 36 demodulates the digital signal. The interface unit 16 transmits a signal between a signal to be transmitted or received by the wireless device 100 and a device that processes the signal, for example, a PC. The modulation unit 42 modulates a signal to be transmitted. The DA converter 40 digital-analog converts the modulated signal and outputs an analog signal. The quadrature modulation unit 38 performs quadrature modulation on the analog signal and outputs an IF signal. The second frequency converter 26 converts the IF signal based on the local signal 204 output from the oscillator 28, up-converts the IF signal here, and outputs an RF signal. The HPA 24 amplifies the RF signal.
The control unit 70 controls operation timing and the like of the wireless device 100.

  FIGS. 2A to 2B show frequency allocation in the vicinity of the 2 GHz band in Japan and Europe. FIG. 2 (a) shows frequency allocation in the case of Japan, where 1.885 GHz to 1.9196 GHz is allocated to the simple mobile phone system, and 1.920 GHz to 1.980 GHz is the third generation mobile phone. Assigned to the system, 1.980 GHz to 2.010 GHz is assigned to the mobile satellite communication service, and 2.010 GHz to 2.025 GHz is assigned to the third generation mobile phone system. On the other hand, FIG. 2B shows frequency allocation in the case of Europe. 1.880 GHz to 1.900 GHz is allocated to the digital cordless telephone system, and 1.900 GHz to 1.920 GHz is the third generation mobile phone. Allocated to the telephone system (TDD), 1.920 GHz to 1.980 GHz allocated to the 3rd generation mobile phone system (FDD), 1.980 GHz to 2.010 GHz allocated to the mobile satellite communications service (FDD) 2.010 GHz to 2.025 GHz is allocated to the third generation mobile phone system (FDD).

  Different radio communication systems are assigned to adjacent frequency bands in both Japan and Europe. Therefore, for example, in the case of a simple mobile phone, the frequency conversion circuit needs to generate an RF signal from the IF signal and reduce the leakage power to the frequency band of the adjacent third generation mobile phone system. On the other hand, the same applies to the third-generation mobile phone system, and when one wireless device 100 is compatible with both the simple mobile phone system and the third-generation mobile phone system, if one system is used, the other It is necessary to reduce the leakage power to the system.

  FIG. 3 shows the configuration of the first frequency converter 22. The first frequency converter 22 includes a first transformer 50, a bridge 52, and a second transformer 54. The first transformer 50 includes a first winding 56 and a second winding 58, the bridge 52 includes a diode D1 to a diode D4, a band elimination filter F1 to a band elimination filter F2, and the second transformer 54 includes a first transformer 54. A winding 60 and a second winding 62 are included. Further, as shown in the figure, the contacts between the diodes in the bridge 52 are indicated by N1 to N4. The second frequency converter 26 has the same configuration.

The first transformer 50 includes a first winding 56 and a second winding 58. One end of the first winding 56 is connected to the LNA 20 (not shown), and the IF signal 202 is input thereto. The other end of the first winding 56 is grounded. The middle point of the second winding 58 is connected to an oscillator 28 (not shown), and the local signal 204 is input. The second transformer 54 forms a bridge with the diodes D1 to D4 in order to frequency-convert the RF signal 200 based on the local signal 204. Further, the nodes N1 and N3 that are not adjacent to each other among the nodes N1 to N4 are connected to both ends of the second winding 58, respectively. Here, two band elimination filters are provided inside the bridge, of which the band elimination filter F1 is arranged in parallel with the diode D2, and the band elimination filter F2 is arranged in parallel with the diode D4. FIG. 4 shows the configuration of the band elimination filter F1. In the band elimination filter F1, an inductor L1 and a capacitor C1 are connected in series. According to such a configuration, the filter characteristic of the band elimination filter F1 is set according to the relationship of f = 1 / (2π (LC) ^1/2 ), as is well known, and attenuates the signal strength. Here, f is a resonance frequency.

  Among the nodes N1 to N4, the remaining nodes N2 and N4 are connected to the first winding 60 of the second transformer 54, respectively. Further, the midpoint of the first winding 60 is grounded. One end of the second winding 62 of the second transformer 54 is connected to the quadrature detection unit 30 (not shown) and outputs an IF signal 202. Due to such a configuration, the IF signal 202 has a frequency determined by the difference between the RF signal 200 and the local signal 204, and further attenuates the frequency region set by the band elimination filter F1 and the band elimination filter F2. Signal. Here, the band elimination filter F1 and the band elimination filter F2 may be set so that the resonance frequencies thereof are the same or different. According to the former, there is one central frequency, and the amount of attenuation is large. On the other hand, according to the latter, there are two center frequencies.

  FIGS. 5A and 5B show the operating principle of the first frequency converter 22. When the local signal 204 is not input, the diodes D1 to D4 are all turned off, so that the first transformer 50 and the second transformer 54 are electrically disconnected. Therefore, the RF signal 200 and the IF signal 202 are separated. When the local signal 204 is in a positive cycle, that is, when the local signal 204 has a positive voltage, the voltage at the node N1 and the node N3 becomes higher than the voltage at the node N2 and the node N4, so that the diode D1 and the diode D3 Are forward biased and turned on, but diode D2 and diode D4 are reverse biased and turned off. Therefore, the electrical connection is as shown in FIG. The arrows in the figure indicate the signal flow, and the RF signal 200 and the IF signal 202 have the same signal flow. Since both the RF signal 200 and the IF signal 202 are alternating current signals, the signal may flow in the direction opposite to the arrow shown in the figure. In this case, the RF signal 200 and the IF signal 202 are in the same direction. Signal flow.

  When the local signal 204 is in a negative cycle, that is, when the local signal 204 has a negative voltage, the voltage at the node N2 and the node N4 becomes higher than the voltage at the node N1 and the node N3, so that the diode D2 and the diode D4 Are forward biased and turned on, but diode D1 and diode D3 are reverse biased and turned off. Therefore, the electrical connection is as shown in FIG. The arrows in the figure indicate the signal flow, and the RF signal 200 and the IF signal 202 have signal flows in opposite directions. Since the RF signal 200 and the IF signal 202 are both AC signals as described above, the signal flow may be in the direction opposite to the arrow shown in the figure. Have signal flow in the opposite direction. The diode used here may be a schottky barrier diode made of a compound semiconductor such as GaAs in addition to a PN junction diode in CMOS.

  FIGS. 6A to 6B show filter characteristics of the frequency conversion unit 22, and these are characteristics after frequency conversion. FIG. 6A shows a case where the resonance frequencies of the band elimination filter F1 and the band elimination filter F2 are set to the same value. As shown in the figure, there is one center frequency, and the signal is attenuated at the center frequency. On the other hand, FIG. 6B shows a case where the resonance frequencies of the band elimination filter F1 and the band elimination filter F2 are set to different values. As shown in the figure, there are two center frequencies, and the signal is attenuated at the two center frequencies. If both are compared, the amount of attenuation is larger in FIG. 6A.

  According to the embodiment of the present invention, since the band elimination filter is arranged inside the passive mixer circuit, it is possible to perform frequency conversion and attenuate a signal having an unnecessary frequency. Also, the circuit can be made smaller than when the mixer circuit and the band elimination filter are separately provided. Further, since the passive mixer circuit is used as a base, power is not consumed.

(Example 2)
A second embodiment of the present invention relates to a frequency conversion circuit that performs frequency conversion of a transmission signal and a reception signal inside a wireless device as in the first embodiment, and the frequency conversion circuit includes a passive mixer circuit. However, unlike the first embodiment, the passive mixer circuit is composed of transistors such as FETs. Since a transformer is not necessarily required, the frequency conversion circuit can be easily made into one chip and can be easily mounted on a wireless device.

  FIG. 7 shows a configuration of the radio unit 110 according to the second embodiment of the present invention. The radio unit 110 includes a balun unit 112, an LNA 114, a frequency conversion unit 116, and an oscillator 118. The signals include a first RF signal 200a, a second RF signal 200b, a first IF signal 202a, a second IF signal 202b, a first local signal 204a, and a second local signal 204b. Here, only the case of using as a receiving apparatus will be described, and the description of the case of using as a transmitting apparatus will be omitted.

  The balun unit 112 converts the signal received by the antenna 10 (not shown) from an unbalanced signal to a balanced signal. The LNA 114, the frequency converter 116, and the oscillator 118 correspond to the LNA 20, the first frequency converter 22, and the oscillator 28 in FIG. 1, respectively, but the RF signal 200, the IF signal 202, and the local signal 204 are balanced signals, respectively. They constitute a differential signal.

FIG. 8 shows the configuration of the frequency converter 116. The frequency converter 116 includes transistors M1 to M4, a band elimination filter F1, and a band elimination filter F2. Further, as shown in the figure, the contacts between the transistors are indicated by N1 to N4.
The transistors M1 to M4 form a bridge with their source terminals or drain terminals connected to each other. Among the bridges, the node N1 is arranged to correspond to the first RF signal 200a, the node N3 to the second RF signal 200b, the node N2 to the first IF signal 202a, and the node N4 to the fourth IF signal 202b. Further, the gate terminals of the transistors M1 and M3 are arranged to correspond to the second local signal 204b, and the gate terminals of the transistors M2 and M4 are arranged to correspond to the first local signal 204a. On the other hand, the band elimination filter F1 is arranged in parallel with the transistor M2, and the band elimination filter F2 is arranged in parallel with M4.

  Since the local signal 204 constitutes a differential signal, either the combination of the transistor M1 and the transistor M3 or the combination of the transistor M2 and the transistor M4 is turned on based on the local signal 204. When the transistors M1 and M3 are turned on, the first RF signal 200a corresponds to the first IF signal 202a, and the second RF signal 200b corresponds to the second IF signal 202b. On the other hand, when the transistors M2 and M4 are turned on, the first RF signal 200a corresponds to the second IF signal 202b, and the second RF signal 200b corresponds to the first IF signal 202a. Therefore, as in the first embodiment, the relationship between the RF signal 200 and the local signal 204 is the same or opposite based on the local signal 204. Since the band elimination filter F1 and the band elimination filter F2 are the same as those in the first embodiment, the band elimination effect can be obtained. The FET used here may be a MESFET manufactured on a compound semiconductor such as GaAs, and a Schottky barrier diode in addition to a CMOS-FET.

  According to the embodiment of the present invention, since it is composed of a transistor and does not include a transformer or the like, it can be easily made into one chip. Since it can be easily made into one chip, it can be easily mounted even if the wireless device is a portable terminal.

(Example 3)
The third embodiment of the present invention relates to a frequency conversion circuit that converts the frequency of a transmission signal and a reception signal inside the wireless device as in the previous embodiments, and the frequency conversion circuit is configured by a passive mixer circuit. However, unlike the previous embodiments, the center frequency of the band elimination filter arranged in the passive mixer circuit can be set from the outside. As a result, the versatility of the frequency conversion path of the present embodiment is enhanced.

The frequency converter according to the third embodiment is the same as the first frequency converter 22 in FIG. 3 and the frequency converter 116 in FIG. Here, the configurations of the band elimination filter F1 and the band elimination filter F2 provided therein are different.
FIG. 9 shows the configuration of the band elimination filter F1 according to the third embodiment of the present invention. The band elimination filter F1 includes an inductor L2, an inductor L3, a capacitor C2, a capacitor C3, a diode D5, a diode D6, a resistor R1, and a resistor R2, and includes a terminal 150 outside. The terminal 150 is provided outside the band elimination filter F1, and can set a predetermined voltage. The diode D5 and the diode D6 are varactor diodes, and the band elimination filter F1 includes the diode D5 and the diode D6 connected in series with the inductor L2, the capacitor C2, the inductor L3, and the capacitor C3. If the voltage set at the terminal 150 is changed, the bias voltages of the diode D5 and the diode D6 are changed. As a result, the resonance frequency of the band elimination filter F1 is changed, and the center frequency for band elimination is also changed. The band elimination filter F2 has the same configuration.

  With such a configuration, when the frequency conversion unit is used in a simple mobile phone system, the center frequencies of the band elimination filter F1 and the band elimination filter F2 are determined in the frequency band used in the third generation cellular phone system. Thus, the designer sets a voltage at the terminal 150. On the other hand, when the frequency conversion unit is used in the third generation mobile phone system, the design is made so that the center frequencies of the band removal filter F1 and the band removal filter F2 are determined in the frequency band used in the simplified mobile phone system. The person sets a voltage at the terminal 150.

  According to the embodiment of the present invention, if the voltage is set from the outside, the center frequency of the band elimination filter can be changed, so that the versatility of the frequency conversion circuit can be increased.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In Embodiments 1 to 3 of the present invention, it is assumed that a simple mobile phone system or a third generation mobile phone system is used as a wireless communication system, and band elimination is performed for interference with a system assigned a frequency adjacent to the frequency of the system to be used. It is reduced by the filter F1 and the band elimination filter F2. However, the present invention is not limited to this. For example, UWB is assumed as a wireless communication system, and interference to frequencies assigned to other systems in the UWB frequency band may be reduced by the band removal filter F1 or the band removal filter F2. . According to this modification, the present invention can be applied to various wireless communication systems. That is, it is only necessary that another system uses a frequency adjacent to the frequency to be used.

  In the first to third embodiments of the present invention, two band elimination filters F1 and F2 are arranged. However, the present invention is not limited to this. For example, one or three or more may be used. Further, in the case of two or more, among the passively used elements included in the bridge, they may be arranged in parallel with the adjacent elements such as the diode D1 and the diode D2, or the transistor M1 and the transistor M2. According to this modification, it is possible to arrange the band elimination filter F1 and the like according to the required filter characteristics. In other words, it may be arranged in parallel with the passively used elements.

It is a figure which shows the structure of the radio | wireless apparatus which concerns on Example 1 of this invention. FIGS. 2A to 2B are diagrams showing frequency allocation in the vicinity of the 2 GHz band in Japan and Europe. It is a figure which shows the structure of the 1st frequency conversion part of FIG. It is a figure which shows the structure of the zone | band removal filter of FIG. FIGS. 5A to 5B are diagrams illustrating the operation principle of the first frequency conversion unit of FIG. 6A to 6B are diagrams illustrating filter characteristics of the first frequency conversion unit in FIG. It is a figure which shows the structure of the radio | wireless part which concerns on Example 2 of this invention. It is a figure which shows the structure of the frequency conversion part of FIG. It is a figure which shows the structure of the zone | band removal filter which concerns on Example 3 of this invention.

Explanation of symbols

  10 antenna, 12 radio unit, 14 processing unit, 16 interface unit, 18 switching unit, 20 LNA, 22 first frequency conversion unit, 24 HPA, 26 second frequency conversion unit, 28 oscillator, 30 quadrature detection unit, 32 AGC, 34 AD converter, 36 demodulator, 38 quadrature modulator, 40 DA converter, 42 modulator, 50 first transformer, 52 bridge, 54 second transformer, 56 first winding, 58 second winding, 60 second 1 winding, 62 2nd winding, 70 control unit, 100 wireless device, 112 balun unit, 114 LNA, 116 frequency conversion unit, 118 oscillator, 150 terminals, 200 RF signal, 202 IF signal, 204 local signal, D1 D6 diode, F1-F2 band elimination filter, N1 N4 nodes, L1 to L3 inductor, C1 to C3 capacitors, M1 to M4 transistors, R1 to R2 resistor.

Claims (8)

A first input unit for inputting a signal to be processed;
A second input unit for inputting a reference signal for converting the frequency of the input signal to be processed;
A converter that converts the frequency of the input signal to be processed based on the input reference signal;
An output unit that outputs a signal to be processed with the frequency converted;
The conversion unit forms a bridge with a plurality of elements used passively, and arranges a band elimination filter between nodes of the plurality of elements used passively,
A mixer circuit characterized in that a predetermined frequency band is attenuated by the band elimination filter for the signal to be processed, which is obtained by converting the frequency output from the output unit. The converter is
A primary winding and a secondary winding, wherein one end of the primary winding is connected to the first input unit, and a midpoint of the secondary winding is connected to the second input unit; The first transformer,
Four diodes as a plurality of passively used elements constituting the bridge respectively connected to both ends of a secondary winding of the first transformer;
A band rejection filter connected between nodes of the four diodes;
Apart from the first transformer, it has a primary winding and a secondary winding, both ends of the primary winding are connected to the four diodes, respectively, and one end of the secondary winding is the A second transformer connected to the output unit,
Of the four contacts of the four diodes, two non-adjacent contacts are respectively connected to both ends of the secondary winding of the first transformer, and the remaining two contacts of the four contacts are The mixer circuit according to claim 1, wherein the mixer circuit is connected to both ends of a primary winding of the second transformer. The first input unit includes two terminals for inputting the signal to be processed that constitutes a differential signal,
The second input unit includes two terminals for inputting the reference signal constituting a differential signal,
The output unit includes two terminals for outputting a signal to be processed to be output, which constitutes a differential signal,
The conversion unit includes four transistors as a plurality of passively used elements constituting the bridge, and a band elimination filter connected between nodes of the four transistors,
Of the four contacts of the four transistors, two non-adjacent contacts are respectively connected to the two terminals of the first input unit, and the remaining two of the four contacts are connected to the output unit. The terminals connected to the two terminals, included in the two transistors not adjacent to each other among the four transistors, and the terminals not connected to the bridge among the transistors are the two terminals of the second input unit. A terminal connected to one of the terminals, included in the remaining two transistors of the four transistors, and not connected to the bridge among the transistors, the two terminals of the second input unit The mixer circuit according to claim 1, wherein the mixer circuit is connected to the other of the two. The band elimination filter arranged in the conversion unit can vary the center frequency,
4. The mixer circuit according to claim 1, further comprising a terminal for setting a center frequency of the band elimination filter from the outside.   5. The mixer circuit according to claim 1, wherein there are two or more band elimination filters arranged in the conversion unit.   6. The mixer circuit according to claim 5, wherein the two or more band elimination filters arranged in the conversion unit are defined so that center frequencies thereof are substantially the same.   The at least one of the two or more band elimination filters arranged in the conversion unit is defined to have a different center frequency with respect to the other band elimination filters. Mixer circuit. A radio unit for processing radio frequency signals;
A frequency converter that converts a frequency between the radio frequency signal and an intermediate frequency signal lower than the radio frequency;
The intermediate frequency signal, and a processing unit for processing a baseband signal lower than the intermediate frequency,
The frequency converter is
A first input unit that inputs one of the radio frequency signal and the intermediate frequency signal as a signal to be processed;
A second input unit for inputting a reference signal for converting the frequency of the input signal to be processed;
A converter that converts the frequency of the input signal to be processed based on the input reference signal;
An output unit that outputs the signal to be processed with the frequency converted as the other of the signal of the radio frequency and the signal of the intermediate frequency;
The conversion unit forms a bridge with a plurality of elements used passively, and arranges a band elimination filter between nodes of the plurality of elements used passively,
A radio apparatus in which a predetermined frequency band is attenuated by the band removal filter for a signal to be processed, which is obtained by converting the frequency output from the output unit.

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