JP2009218637A - Mixer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise by a harmonic component of a local oscillator signal in a direct conversion system and a low IF system. <P>SOLUTION: In a mixer, a three-phase signal, where phases differ by 120° each, is used as a local oscillation signal and is multiplied by a reception signal, and the in-phase signal of each demodulation wave is canceled, thus canceling a noise component by a third harmonic in harmonic components of the local oscillation signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mixer used in a digital broadcast image receiver or audio receiver. More specifically, the present invention relates to a mixer that mixes these signals and a local oscillation signal when modulating a communication signal or synchronously detecting a received signal.

  In recent years, tuners that do not have a tracking filter have been used with the downsizing of tuners. This type of tuner has a problem in that an interference wave is received by the harmonics of the local oscillator signal. Specifically, a direct conversion type receiver may receive a signal having a frequency three times the reception frequency, which may degrade the S / N ratio for receiving a desired wave.

  In order to solve this problem, a method of canceling a signal with respect to a harmonic of a local oscillator signal has been proposed (Patent Document 1). In this approach, when trying to cancel the interference wave caused by the third harmonic of the local oscillator signal, the local oscillator signals whose phases are different from each other by 60 degrees are applied to the two mixers and their outputs are added. Usually, a direct conversion type or low IF type tuner requires an output signal of two or more phases, so the method of Patent Document 1 requires four mixers to obtain a two-phase output signal. As a local oscillator signal, not only signals having phases of 0 ° and 60 ° but also signals of 90 ° and 150 ° are required. However, it is not easy to generate these signals with high accuracy.

  On the other hand, Non-Patent Document 1 proposes a method of canceling interference waves with respect to harmonics of a local oscillator signal using local oscillator signals whose phases are shifted by 45 ° from each other. However, in addition to requiring many mixers, it is necessary to accurately realize a mixer gain ratio that is not an integer ratio such as 1: √2, and it is difficult to expect high harmonic cancellation accuracy.

Further, there is a method using a three-phase local oscillator signal (Non-Patent Document 2) as a method for removing the interference wave caused by the third harmonic of the local oscillator. There was a problem that the waves could not be removed.
USPAT. 6766158 IEEE JSSC 36-12, pp. 2003-2015, 2001 Yamaji, T .; Itakura, T .; Ito, R .; Ueno, T .; Okuni, H .; Balanced 3-phase analog signal processing for radio communications IEEE International Symposium on Circuits and Systems, 2006. ISCAS 2006. Proceedings. pp. 21-24, 2006

  The direct conversion method and the low IF method are often used for receiving and transmitting devices in a situation where further downsizing is required and a higher signal band is used. However, the conventional technology as described above has a problem that the device cannot be miniaturized because a large number of phases are required for the local oscillator signal in order to cancel the third harmonic.

  Therefore, in the present invention, a mixer that can be used for a direct conversion type or low IF type receiver can be realized, which can realize a function of canceling the received signal with respect to the third harmonic of the local oscillator signal while suppressing the number of phases of the local oscillator. It aims to be realized. In particular, the object is to obtain a configuration in which the number of phases of the local oscillator and the number of mixers are reduced as much as possible, and a ratio such as a gain other than 1: 1 is not required.

That is, in order to achieve the above object, the present invention
A signal input terminal to which a balanced signal is input;
The signal input terminal is connected to an input terminal, each of which is a mixer having three switching units each having a signal output terminal and a switching signal input terminal,
Each switching part
By the switching signal input to the switching signal input terminal,
Connect the input terminal and the signal output terminal,
Connect the inverted output of the signal input terminal to the signal output terminal,
Do not connect the signal input terminal and the signal output terminal,
A mixer that is a switching unit that selects any one of the states is provided.

  Since the mixer of the present invention can obtain an output signal whose phase is different by 120 degrees by switching the input signal using the three-phase local oscillator signal and demodulating it by the third harmonic component of the local oscillation signal. Canceled signal can be canceled out. Further, by setting the local oscillator signal to 6 phases, the number of phases becomes an even number, and signal processing in the mixer is performed so that the local oscillator signal is also balanced, thereby disturbing the second harmonic wave of the local oscillator signal. Can be removed. That is, even if there are many second harmonic components and third harmonic components of the local oscillator signal, a good S / N signal can be demodulated.

  As a specific example, the frequency band used by a mobile phone in the vicinity of about 2 GHz has a three-fold relationship with the frequency of a signal of about 400 MHz to 700 MHz used in television broadcasting. Therefore, by using the mixer of the present invention as a tuner when demodulating a signal in the television broadcast band, it is possible to avoid the signal in the cellular phone band being demodulated at the same time and the S / N of the signal being deteriorated.

(Embodiment 1)
The operation principle of the mixer of the present invention will be described.
Consider a case where an input signal that is a high-frequency signal is mixed with a three-phase local oscillator signal in a mixer to obtain a three-phase output signal that is a baseband signal. Assuming that the input signal is asin (ωst + φ), the angular frequency of the local oscillator signal is ω _L , and the mixer output does not include a modulation component due to the second harmonic of the local oscillator signal, the third harmonic of the local oscillator signal The mixer output in consideration up to is given by the equations (1), (2) and (3).

ただし、ｋ、ｈはそれぞれ変換ゲインである。

However, k and h are conversion gains, respectively.

  Here, the components of the mixer output signal with respect to the fundamental wave of the local oscillator signal are shifted in phase by 120 degrees in the three phases, whereas the components of the local oscillator signal with respect to the third harmonic are all in phase. Therefore, the signal component for the third harmonic of the local oscillator signal can be removed by removing the in-phase component of the three-phase signal.

  That is, the high-frequency signal is mixed with the three-phase local oscillator signal while preventing the modulation component due to the second harmonic of the local oscillator signal from being included, and as a result, the three-phase signal is extracted. Solve problems. For this purpose, a high-frequency signal is mixed with a 6-phase local oscillator signal to obtain a 3-phase output signal. By making the local oscillator signal into 6 phases, the number of phases becomes an even number, and the signal processing in the mixer is performed so that the local oscillator signal is also balanced, thereby eliminating the interference wave caused by the second harmonic of the local oscillator signal. can do.

  FIG. 1 shows a configuration of a mixer according to the present invention for realizing the above principle. The mixer 1 of the present invention includes signal input terminals (RF + and RF−) and three switching units (10, 11, 12). A differential signal is input to the signal input terminal. Each switching unit has two signal output terminals (OP1, ON1, and OP2, ON2 and OP3, and ON3). Each switching unit has two input terminals, and each is connected to a signal input terminal.

  A switching signal (15, 16, 17) is input to the switching unit separately, and the connection state between the signal input terminal and the signal output terminal input by the switching signal is switched. A terminal to which a switching signal is input is a switching signal input terminal. The switching signal is a signal in which the phase of the signal of the local oscillator differs by 120 degrees. Here, it is assumed that the switching signal 15 has a phase of 0 °, the switching signal 16 has a phase of 240 °, and the switching signal 17 has a phase of 120 °. Each signal is also given a signal shifted by 180 °. This is because the switching signal is input as a differential signal.

  Therefore, the switching signal 15 is given not only 0 ° but also a 180 ° signal. Similarly, a signal having a phase of 420 ° is given to the switching signal 16, and a signal of 300 ° is given to the switching signal 17. A signal having a phase of 420 ° is the same as a signal having a phase of 60 °. Eventually, the switching signal is composed of signals having six phases of 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °.

  Since the three switching units have the same configuration, the switching unit 10 will be further described. The switching-up 10 is a switch that switches input differential signals simultaneously. The switching state has three states: the differential signal is connected to the terminal 21 and the terminal 23, is connected to the terminal 22 and the terminal 24, and is not connected to either terminal. Terminals 21 and 24 are connected to signal output terminal OP1, and terminals 22 and 23 are connected to ON1.

  That is, when the input differential signal is connected to the terminals 21 and 23, RF + is output to the signal output terminal OP1, and RF- is output to ON1. When a differential signal is connected to the terminal 22 and the terminal 24, RF− is output to OP1, and RF + is output to ON1. If the differential signal is not connected to any terminal, the output between OP1 and ON1 becomes zero.

  When the phase of the switching signal 15 is between 0 ° and 60 °, RF + is output to OP1 and RF− is output to ON1. Also, when the phase of the switching signal 15 is 180 ° to 240 °, RF− is output to OP1 and RF + is output to ON1.

  Switching units 11 and 12 perform the same operation as switching unit 10 by a phase of 120 °, that is, delayed by 2/3 period and 4/3 period, because the switching signals differ by 120 degrees.

  FIG. 2 shows the mixer 2 of the present embodiment with a more specific circuit configuration. The input signal is connected to RF + and RF−. Input signals are respectively connected to the gates of the transistor M1 (hereinafter, the transistor is simply referred to as “M1” or the like) and the gate of M2. The sources of M1 and M2 are connected together and grounded through a common current source I1. The drains of M1 and M2 are connected to the power supply voltage Vsup through current sources I2 and I3, respectively. Therefore, a differential amplifier is constituted by M1, M2, I1, I2, and I3, and an input signal is received by this differential amplifier.

  LO0, LO60, LO120, LO180, LO240, and LO300 are each input with a local oscillator signal whose phase is different from that of one of the local oscillator signals by 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °. This corresponds to the input of the switching signal in FIG. Further, there are three switching units for receiving these switching signals as in FIG.

  The switching unit to which LO0 and LO180 are input includes M3, M4, M9, and M10. The switching unit to which LO120 and LO300 are input is configured by M7, M8, M13, and M14. The switching unit to which LO 240 and LO 60 are input is configured by M5, M6, M11, and M12.

  If attention is paid to the switching unit to which LO0 and LO180 are input, the drains of M3 and M10 are connected to OP1, and the drains of M4 and M9 are connected to ON1. Further, the drains of M3 and M4 are connected to the power supply voltage Vsup via resistors R1 and R2, respectively.

  The switching signal LO0 is input to the gates of M3 and M4, and LO180 is input to the gates of M9 and M10.

  The sources of M3 and M9 are connected to node P1, which is the drain of M1, and the sources of M4 and M10 are connected to node P2, which is the drain of M2.

  Similarly, when attention is paid to the switching unit to which LO120 and LO300 are input, the drains of M7 and M14 are connected to OP3, and the drains of M8 and M13 are connected to ON3. Further, the drains of M7 and M8 are connected to the power supply voltage Vsup via resistors R5 and R6, respectively.

  Switching signal LO120 is input to the gates of M7 and M8, and LO300 is input to the gates of M13 and M14.

  The sources of M7 and M13 are connected to the node P1, which is the drain of M1, and the sources of M8 and M14 are connected to the node P2, which is the drain of M2.

  When attention is paid to the switching unit to which LO240 and LO60 are input, the drains of M6 and M13 are connected to OP2, and the drains of M5 and M12 are connected to ON2. Further, the drains of M5 and M6 are connected to the power supply voltage Vsup via resistors R3 and R4, respectively.

  The switching signal LO240 is input to the gates of M13 and M12, and LO60 is input to the gates of M5 and M6.

  The sources of M5 and M11 are connected to the node P1, which is the drain of M1, and the sources of M6 and M12 are connected to the node P2, which is the drain of M2.

Transistors M1 and M2 and constant current sources I1, I2 and I3 form a transconductance amplifier (an amplifier which receives voltage and outputs current), and converts an input signal voltage which is a high frequency signal into a current signal. . When the currents flowing through the constant current sources I1, I2, and I3 are substituted by element names, the relationship of the expression (4) is established.
I1> I2 + I3 (4)
However, here, I2 = I3.

  The constant current sources I2 and I3 are for reducing the direct current component of the current flowing through the switching elements in the mixing, and are intended to reduce 1 / f noise generated during switching. The constant current sources I2 and I3 may be resistors, and the constant current sources I2 and I3 may not be provided.

The operation of the circuit connected as described above will be described. First, since each switching signal is connected to the gate of the N-channel FET, assuming that the switching signal is a sine wave, when a certain switching signal is larger than the value of X, all the other switching signals are values less than or equal to X. There exists a value X such as And it maintains this relationship while the phase advances by 60 °. The angle that is the range of this phase is called the conduction angle. Specifically, the switching signal LO0 has a value of X or more during the phase angle between 60 °, and during this period, the values of the other switching signals are smaller than this. That is, during this phase angle of 60 °, only the transistors M3 and M4 whose LO0 is connected to the gate are in the ON state. Then, inverted voltages of RF + and RF− are output to the drain of M3 and the drain of M4. On the other hand, when LO180 is input, M9 and M10 are turned on. A current flowing through the drain of M4 flows through M9, and a current flowing through M3 flows through M10. Therefore, inverted voltages of RF− and RF + are output to the drains of M10 and M9. This is the same as the operation of the switching unit 10 in FIG.

  The switching unit to which LO120 and LO300 are input operates similarly to the switching unit to which LO240 and LO60 are input.

  In other words, it is as follows. For the high-frequency current signal input to the mixer, the output from the node P1 is switched by the transistors M3, M5, M7, M9, M11, and M13, and the six output signal terminals OP1, ON1, OP2, ON2, Sorted into OP3 and ON3. Similarly, the amount output from the node P2 is switched by the transistors M4, M6, M8, M10, M12, and M14, and distributed to the six output signal terminals OP1, ON1, OP2, ON2, OP3, and ON3. Current distribution is performed by comparing the local oscillator signals LO0, LO60, LO120, LO180, LO240, and LO300. That is, according to the phase of the local oscillator signal, the transistor to be switched is changed every time the phase changes by 60 degrees, and current distribution is performed.

  At this time, the interference wave due to the second harmonic of the local oscillator signal appears as an in-phase signal with respect to the three-phase output signal, and can be eliminated by treating it as a differential signal. For example, when the output signal terminals OP1 and ON1 are considered as differential signal outputs, the signal from the node P1 is distributed to the output signal terminal OP1 by a conduction angle of 60 degrees, and is also distributed to the output signal terminal ON1 by a conduction angle of 60 degrees. . Since the conduction angles of each other are shifted by 180 degrees, as a result, the modulation component due to the second harmonic of the local oscillator signal appears equally at the output signal terminals OP1 and ON1. This is because the second harmonic component of the signal shifted by 180 degrees is the same signal with the same phase and size.

FIG. 3 shows a configuration example of the tuner 4 using the mixer of the present invention.
3 includes an LNA 110, a first mixer 115, a first local oscillator 170, a low-pass filter filter 121, an in-phase signal removal amplifier 133, a BB signal polyphase filter 142, a second mixer 150, a second local oscillator 175, A second IF filter 161 and a buffer 165 are included. Here, the first mixer 115 is the mixer 1 of FIG.

  The tuner 4 is a down-up conversion method in which the RF signal Srf is once dropped into a three-phase baseband signal and then converted into an IF signal.

  The first mixer 115 mixes the input signal from the LNA 110 with the three-phase signal Slo1 from the six-phase first local oscillator 170 to obtain a baseband signal Sd3. This Sd3 is a signal having the same waveform and different phases by 120 °. In this signal, a component from the third harmonic of the RF signal Srf exists as an in-phase signal.

  The output Sd3 of the first mixer 115 is passed through the low-pass filter 121 to remove other interference waves as much as possible. The output Sd3f of the low-pass filter 121 is input to the common-mode signal removal amplifier 133. At this time, the frequency component three times that of the RF signal superimposed as an in-phase signal is canceled.

  The output Sdf of the in-phase signal removal amplifier 133 is a three-phase baseband signal. The adjacent wave is removed from this signal by using the BB signal polyphase filter 142 to obtain a signal Sdff. After that, the frequency is converted into a single-phase IF signal Sif1 by the second mixer 150, and an extra component is removed by a normal IF filter 161 to obtain the signal Sif1f, and then the output is output from the output amplifier 165.

  FIG. 4 shows a configuration example of the first local oscillator 170 that outputs the three-phase signal Slo1. FIG. 4 shows a ring oscillator that outputs a three-phase signal. This ring oscillator includes inverters V1 to V6, capacitors C1 to C6, a constant current source Ic, and output terminals OUT1 to OUT6. The inverters V1, V2, and V3 are connected so that each output becomes the input of the next inverter, and the output of the inverter V3 is connected to the input of the inverter V1. That is, the inverters V1 to V3 are connected in a ring shape. Here, the inverter is used as the same meaning as the inverting amplifier.

The output of the inverter V1 is connected to the input of the inverter V4 via the capacitor C1, and the input of the inverter V1 is connected to the output of the inverter V4 via the capacitor C2.
Similarly, the output of the inverter V2 is connected to the input of the inverter V5 via the capacitor C3, and the input of the inverter V2 is connected to the output of the inverter V5 via the capacitor C4.

  The output of the inverter V3 is connected to the input of the inverter V6 via the capacitor C5, and the input of the inverter V3 is connected to the output of the inverter V6 via the capacitor C6. In other words, the inverter V1 in the first amplifier row corresponds to the inverter V4 in the second amplifier row. Similarly, inverters V2 and V5 and inverters V3 and V6 also correspond.

  The inverters V1 to V6 are driven by a drive power supply Vcc, and a constant current source Ic is connected to the ground side. The output terminals OUT1 to OUT6 are connected to the output terminals of the inverters V1 to V6. The inverter connected in this way operates as follows.

  First, paying attention to the inverters V1, V2, and V3, if the input of the inverter V1 is initially zero, the output becomes 1 after the delay time t. This output becomes the input of the inverter V2, and after a delay time t, the inverter V2 becomes a zero output. Similarly, this output becomes the input of the inverter V3, and the inverter V3 outputs 1 after the delay time t. The output of the inverter V3 becomes the input of the inverter V1, and the same operation is repeated thereafter.

  That is, the output of the inverter V1 changes every 3t, and the cycle is 6t. The same applies to the outputs of the inverters V2 and V3. However, when viewed from the inverter V1, the output of the inverter V3 is delayed by 2t, and the output of the inverter V2 is delayed by 4t. Since the period is 6t, 2t corresponds to 120 degrees in phase, and 4t corresponds to 240 degrees.

  Thus, the outputs of the inverters V1, V2, and V3 are signals whose phases are shifted by 240 degrees and OUT3 by 120 degrees, assuming that the phase of OUT1 is zero degrees. In this sense, OUT1 is represented as P0, OUT2 as P240, and OUT3 as P120.

  The inverters V4, V5, and V6 respectively capacitively couple the outputs of the corresponding inverting amplifiers so that the phase difference is 180 degrees. By doing so, the phase difference between the two ring oscillators can be surely set to 180 degrees, and as a result, six-phase oscillation signals having different phase differences of 60 degrees can be obtained.

  In the first embodiment of the present invention, FET is used for the transistors M1 and M2 which are amplifying elements and the transistors M3 to M14 which are switching elements, but bipolar transistors may be used as shown in FIG. . In FIG. 5, the mixer 3 is replaced with bipolar transistors Q1 to Q14 based on the gates of the transistors M1 to M14 of FIG. 1 so that the source becomes the emitter and the drain becomes the collector.

  Further, a bipolar transistor may be used as the amplifying element, a FET may be used as the switching element, a FET may be used as the amplifying element, and a bipolar transistor may be used as the switching element.

(Embodiment 2)
FIG. 6 is a circuit diagram of the mixer 4 according to the second embodiment of the present invention. The principle is the same as that of the first embodiment of the present invention, except that the mixer has a folded structure. In the first embodiment of the present invention, the transistors M3 to M14 are N-channel, whereas in the second embodiment of the present invention, the transistors M3 to M14 are P-channel. Is a point. The direction of the direct current component of the current is reversed by the constant current sources I2 and I3. For this purpose, it is necessary to satisfy the condition of the following equation (5) with respect to the current value of the constant current source.
I1 <I2 + I3 (5)
However, I2 = I3.

  An advantage of the folded structure of the mixer is that the power supply voltage can be set low. Since the transconductance amplifier unit of the mixer and the switching and load unit do not have to be stacked vertically, low voltage operation is possible. A further advantage of the folded structure is that an N-channel transistor can be used for the transconductance amplifier section and a P-channel transistor can be used for the switching section. The N channel is more advantageous as the amplification performance of the transistor, while the P channel is more advantageous from the viewpoint of 1 / f noise generation. By using a folded structure, 1 / f noise can be reduced without degrading amplification performance, which is particularly advantageous when used in a direct conversion type tuner.

  In the second embodiment of the present invention, FET is used for the transistors M1 and M2 which are amplifying elements and the transistors M3 to M14 which are switching elements, but bipolar transistors may be used for the amplifying elements and switching elements. . Further, a bipolar transistor may be used as the amplifying element, a FET may be used as the switching element, a FET may be used as the amplifying element, and a bipolar transistor may be used as the switching element.

(Embodiment 3)
FIG. 7 is a circuit diagram of the mixer 5 according to the third embodiment of the present invention. The principle is the same as that of the first embodiment of the present invention, except that the mixer structure is a switching mixer. As a load for the output terminals OP1, ON1, OP2, ON2, OP3, and ON3, the DC impedance for the common mode is made sufficiently high. In the first and second embodiments of the present invention, a direct current flows through the switching element, but in the third embodiment of the present invention, a direct current component is included in the current flowing through the switching element. Is not included.

  The advantage of using a switching mixer as the mixer structure is that 1 / f noise can be greatly reduced. However, it is necessary to take into consideration that the level of the local oscillator signal needs to be considerably increased and that distortion with respect to a large signal occurs.

  In the third embodiment of the present invention, the FET is used for the transistors M1 and M2 which are amplifying elements, but a bipolar transistor may be used for the amplifying elements. Since a bipolar transistor requires a DC current to be superimposed on a signal in order to perform a signal switching operation, the transistors M3 to M14 which are switching elements still use FETs.

(Embodiment 4)
A circuit diagram of the mixer 6 according to the fourth embodiment of the present invention is shown in FIG. This mixer is a mixer used for a transmitter, and modulates a baseband signal with a local oscillator signal to generate a high-frequency signal. The baseband signal is a balanced three-phase signal, and the local oscillator signal uses a six-phase signal as a balanced three-phase signal.

  One switching unit is responsible for each of the three balanced baseband signals. As an example, a connection relationship will be described for the switching unit 20 in which BP1 and BN1 are input terminals. BP1 and BN1 are connected to the gates of transistors M1 and M2. Transistors M1 and M2 have their sources connected in common and are grounded via a constant current source I1. Two transistors each having a source connected in common are connected to the drains of the transistors M1 and M2.

  That is, the sources of the transistors M3 and M4 are connected to the drain of the transistor M1, and the sources of the transistors M5 and M6 are connected to the drain of the transistor M2. The drains of the transistors M3, M4, M5, and M6 are connected to the output terminals OP and ON, and are connected to the power supply voltage via the resistors R1 and R2.

  The zero-phase signal terminal of the six-phase local oscillator is connected to the gates of the transistors M3 and M5, and the 180-degree signal terminal is connected to the gates of the transistors M4 and M6. The drains of the transistors M3 and M6 are connected to the output terminal OP, and the drains of the transistors M4 and M5 are connected to the output terminal ON. The output terminals OP and ON are connected to the power supply voltage via R1 and R2, respectively.

  The other two switching units are based on this, and the transistors M1, M2, M3, M4, M5, and M6 are M7, M8, M9, M10, M11, and M12, and M13, M14, M15, and M16, respectively. , M17, M18.

  The signal of each phase of the baseband signal is modulated by each switching unit by one balanced phase of the local oscillator signal, and all of their outputs are added together. Since each phase is modulated by a double balanced mixer, the high-frequency signal as the output signal does not include the second harmonic component of the local oscillator signal. The third harmonic component of the local oscillator signal is included in the high-frequency signal of each phase that is an output signal that is modulated by the baseband signal. However, the third harmonic signal of the local oscillator signal is canceled when all three-phase outputs are added. This is because the third harmonic component of each phase of the local oscillator signal has the same phase, and the sum of the three-phase signals of the baseband signal is zero.

  A configuration example of the transmitter is shown in FIG. The mixer 6 of the present embodiment is a mixer 186 in this figure. The baseband signal is assumed to be given as a two-phase digital signal (PCM signal) 180. A baseband signal which is a two-phase digital signal is converted into a three-phase digital signal by digital signal processing performed by a three-phase two-phase converter. Two of the three phases are converted into analog signals by a DAC (digital-analog converter) 182. The two-phase signals converted into analog signals are added to generate a signal multiplied by −1, and this is used as the remaining one-phase signal 191. The reason for not using three DACs is to suppress an increase in circuit scale. Thereafter, the signal is transmitted from the amplifier 187 through the mixer 186 as an RF signal not including the second and third harmonic signals.

In the fourth embodiment of the present invention, FETs are used for the transistors M1, M2, M7, M8, M13, and M14 that are amplifying elements and the transistors M3 to M6, M9 to M12, and M15 to M18 that are switching elements. However, bipolar transistors may be used for the amplifying element and the switching element. Further, a bipolar transistor may be used as the amplifying element, a FET may be used as the switching element, a FET may be used as the amplifying element, and a bipolar transistor may be used as the switching element.

  The tuner of the present invention can be used for a receiver that receives a radio signal.

The figure which shows the structure of the mixer of this invention. The figure which shows the specific circuit structure which implement | achieves the mixer of this invention. The figure which shows the structure of the tuner using the mixer of this invention. The figure which shows the structure of the local oscillator input into the mixer of this invention. The figure which shows the structure at the time of replacing the transistor of FIG. 2 with the bipolar type. The figure which shows the case where the mixer of this invention is comprised by P channel type FET. The figure which shows the structure at the time of omitting load resistance in the mixer of this invention. The figure which shows the circuit structure of the mixer for transmission of this invention. The figure which shows the structure of the transmitter using the mixer of FIG.

Explanation of symbols

1 to 6 Mixer 10 to 12 Switching unit 15 to 17 Switching signal 400 Tuner

Claims (5)

A signal input terminal to which a balanced signal is input;
The signal input terminal is connected to an input terminal, each of which is a mixer having three switching units each having a signal output terminal and a switching signal input terminal,
Each switching part
By the switching signal input to the switching signal input terminal,
Connect the input terminal and the signal output terminal,
Connect the inverted output of the signal input terminal to the signal output terminal,
Do not connect the signal input terminal and the signal output terminal,
A mixer that is a switching unit that selects one of the states. A signal input terminal to which a balanced signal is input;
A mixer having first, second and third switching sections,
The signal input terminal is connected to each other and grounded via a constant current source, and the drain is connected to the gates of the first and second input transistors connected to the constant voltage source via the constant current source,
Each of the first, second and third switching units has four transistors, two resistors and two signal output terminals,
The first transistor is
A source connected to the drain of the first input transistor;
The drain is connected to the voltage source via the first signal output terminal and the first resistor;
The gate is connected to the first switching signal terminal;
The second transistor is
A source connected to the drain of the second input transistor;
A drain connected to a voltage source via a second signal output terminal and a second resistor;
The gate is connected to the first switching signal terminal;
The third transistor is
A source connected to the drain of the first input transistor;
A drain connected to the second signal output terminal;
A gate is connected to the second switching signal terminal;
The fourth transistor is
A source connected to the drain of the second input transistor;
A drain connected to the first signal output terminal;
A mixer having a gate connected to the second switching signal terminal. The mixer according to claim 2, wherein the four transistors constituting the three switching units are P-channel FETs. A signal input terminal to which a balanced signal is input;
A mixer having first, second and third switching sections,
The signal input terminal has first and second inputs connected to each other and grounded via a constant current source, and each drain is connected to a constant voltage source via first and second resistors. Connected to the gate of the transistor,
Each of the first, second and third switching units has four transistors, two resistors and two signal output terminals,
The first transistor is
A source connected to the drain of the first input transistor;
The drain is connected to the first signal output terminal;
The gate is connected to the first switching signal terminal;
The second transistor is
A source connected to the drain of the second input transistor;
The drain is connected to the second signal output terminal;
The gate is connected to the first switching signal terminal;
The third transistor is
A source connected to the drain of the first input transistor;
A drain connected to the second signal output terminal;
A gate is connected to the second switching signal terminal;
The fourth transistor is
A source connected to the drain of the second input transistor;
A drain connected to the first signal output terminal;
A mixer having a gate connected to the second switching signal terminal. First, second, and third switching units each having a signal input terminal to which a balanced signal is input, and first and second switching signal terminals to which a switching signal is input;
The outputs of the first, second and third switching units are connected;
Connected to the supply voltage through a resistor,
A mixer having first and second signal output terminals for outputting a balanced signal,
Each of the switching units has six transistors,
The signal input terminal is connected to gates of first and second input transistors, the sources of which are connected to each other and grounded through a constant current source,
The drain of the first transistor is connected to the sources of the third and fourth transistors connected to each other;
The drain of the second transistor is connected to the sources of the fifth and sixth transistors whose sources are connected to each other;
The drains of the third and sixth transistors are connected to the first signal output terminal,
The drains of the fourth and fifth transistors are connected to the second signal output terminal,
Gates of the third and fifth transistors are connected to the first switching signal terminal;
A mixer in which gates of the fourth and sixth transistors are connected to the second switching signal terminal.

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