JP6346651B2 - Multiband RF receiver - Google Patents

Description

  The present invention relates to a multiband RF receiver, and more specifically to a multiband RF receiver that improves linearity by using a low noise amplifier as a transimpedance amplifier at the front end of a mixer.

  In a mobile TV tuner environment using ISDB-T (UHF Band: 470 MHz to 770 MHz), harmonic mixing by a local oscillator (Local Oscillator) with a frequency of 700 MHz to 2.4 GHz used in 3G or 4G. Factors that degrade performance due to Harmonic Mixing, and degradation due to second order intermodulation (IM2) and third order intermodulation (IM3) that occur within 90MHz to 2.4GHz. It is necessary to solve the part. In the existing mobile TV tuner environment, a modulation tone generated by IM2 between FM bands is generated in the UHF band, and is removed using an RF input filter.

  However, even when the filter is realized by the PCB board, the signal radiated from the rear part of the filter end needs to be immediately received by the TV tuner chip, so that it is necessary to improve the performance of the existing circuit. In the case of IM3, the modulation tone generated between channels is also a problem in performance, but IM3 performance generated in the LTE band ((cf) 700 MHz to 900 MHz) is chipped with a large power jammer in the same module. Needs to improve the performance of IM2 and IM3.

  Therefore, the LTE band may require the assistance of a surface acoustic wave filter (SAW Filter) with a TV tuner chip due to the large power. By the way, when a surface acoustic wave filter is used at the input of the chip, there arises a problem that sensitivity is lowered due to loss due to the filter.

  In order to prevent such a decrease in sensitivity, it is necessary to improve the performance of IIP2 (Second Order Input Intercept Point) and IIP3 (Third Order Input Intercept Point) by improving linearity.

(Patent Document 0001) Korean Patent Publication No. 10-2015-0053168 A low noise amplifier having a high linear characteristic (May 15, 2015)
(Patent Document 0002) Korean Patent Publication No. 10-2015-0053169 Double Band Low Noise Amplifier (May 15, 2015)

  As described above, the present invention is an invention that solves the technical problem, and provides a multiband RF receiver capable of improving the performance of IIP2 and IIP3 by improving linearity in a mobile TV tuner environment. The purpose is to do.

  Therefore, the present invention also has an object to provide a multiband RF receiver capable of optimizing the number of semiconductor pins necessary for connection with an external filter element.

  An RF receiver according to a preferred embodiment of the present invention includes a low noise amplification unit including a plurality of low noise amplifiers, and a mixer unit including at least one mixer for converting a frequency using an output of the low noise amplification unit. And a switch unit that can be selected to input the output of the low noise amplifying unit to the mixer unit or to input the output of the low noise amplifying unit to the mixer unit via an external element. Preferably, each of the plurality of low-noise amplifiers outputs a single-ended signal, and the at least one mixer is a single balanced mixer.

  Each output of the plurality of low noise amplifiers is preferably combined into one. Accordingly, the low noise amplification unit further includes a third capacitor connected to the outputs of the plurality of low noise amplifiers combined.

  Preferably, the switch unit includes a first switch disposed between the output of the third capacitor and the input of the mixer unit, and a first switch disposed between the output of the third capacitor and one end of the external element. 2 switches, and the 3rd switch arrange | positioned between the other end of the said external element, and the input of the said mixer part, It is characterized by the above-mentioned. Each of the first switch, the second switch, and the third switch includes at least one basic switching component.

  The basic switching component includes one transistor, a first basic switching component resistor connected to a first terminal of the one transistor, a second terminal of the one transistor, and a third terminal of the one transistor. And a resistor for a second basic switching component connected therebetween.

  Specifically, each of the first switch, the second switch, and the third switch includes three basic switching components, and the three basic switching components include a first basic switching component, a second basic switching component, a second switch 3 basic switching components. A third terminal of a fifth transistor included in the first basic switching component; a second terminal of a sixth transistor included in the second basic switching component; and a seventh terminal of a seventh transistor included in the third basic switching component. The three terminals are preferably connected to each other. Accordingly, the fifth transistor, the sixth transistor, and the seventh transistor each perform on / off operations, the sixth transistor performs on / off operations similar to the fifth transistor, and the seventh transistor An ON or OFF operation opposite to that of the fifth transistor is performed.

  Preferably, the low noise amplification unit, the switch unit, and the mixer unit are configured inside one semiconductor chip, and the external element is an element located outside the one semiconductor chip.

  Accordingly, each of the plurality of low-noise amplifiers includes a first portion that amplifies an RF signal and a second portion that outputs or does not output the output of the first portion. Preferably, when the corresponding low noise amplifier is in use among the plurality of low noise amplifiers, the second portion outputs an output of the first portion, and among the plurality of low noise amplifiers, The output of the first part is not output when another low noise amplifier that is not a noise amplifier is in use. Specifically, the first part includes a first transistor and a second transistor, and the second part includes a 2-1 switch and a 2-2 switch, and is between the first transistor and the second transistor. Preferably, the 2-1 switch and the 2-2 switch are connected.

  In addition, a signal is input to the first terminal of the first transistor and the first terminal of the second transistor via the first capacitor and the second capacitor, respectively.

  Preferably, each of the plurality of low noise amplifiers includes a first resistor, one end of the first resistor is connected to a first terminal of the first transistor, and the other end of the first resistor is a corresponding low noise amplifier. It is connected to the output of Preferably, the second transistor control signal is input to the first terminal of the second transistor via a high impedance element. Accordingly, the 2-1 switch and the 2-2 switch include a third transistor and a fourth transistor, respectively, and the first terminal of the third transistor and the first terminal of the fourth transistor. The third transistor control signal and the fourth transistor control signal are input to each via a high impedance element.

  The multiband RF receiver of the present invention can improve the linearity in a mobile TV tuner environment, improve the performance of IIP2 and IIP3, and further the number of semiconductor pins required when connecting to an external filter element Can be optimized.

FIG. 1 is a configuration diagram of a conventional passive mixer device (140). FIG. 2 is a block diagram of an RF receiver (200) according to a preferred embodiment of the present invention. FIG. 3 is a circuit diagram of a low noise amplifier (221a, 221b) according to a preferred embodiment of the present invention. FIG. 4 is a circuit diagram of one embodiment of the first switch (SW1), the second switch (SW2), and the third switch (SW3).

  Hereinafter, a multiband RF receiver according to an embodiment of the present invention will be described in detail with reference to the drawings.

  The following examples of the present invention are intended to embody the present invention and are not intended to limit or limit the scope of rights of the present invention. What can be easily inferred by those skilled in the art to which the present invention pertains from the detailed description and examples of the present invention should be construed as belonging to the scope of the present invention.

  FIG. 1 is a configuration diagram of a conventional passive mixer device (140).

  As shown in FIG. 1, a conventional passive mixer device (140) includes a transconductance (Gm) amplifier (141), a mixer (142) that receives a signal from a local oscillator (LO) and converts the frequency, and a transimpedance. It includes an amplifier (Transimpedance Amplifier, 143).

  Conventionally, a low noise amplifier (LNA) is used as one amplifier, and the transimpedance amplifier (141) of the mixer device (140) uses a single differential amplifier (Single-to-Differential Amplifier). In many cases, it has been used as a double-balanced passive mixer (Double-Balanced Passive Mixer). However, in this case, the active circuit (Active Circuit) becomes two stages (Stage), and the linearity is hardly improved.

  Accordingly, in general, the output of the low noise amplifier is often implemented differentially so that the low noise amplifier performs the role of the transimpedance amplifier of the mixer apparatus at the same time.

  However, since the multi-band RF receiver (200) of the present invention has a selective path that can use an external filter (F) between the low noise amplifiers (221a, 221b) and the mixer unit (240), A method is proposed in which the output of the noise amplifier (221a, 221b) is single and the input of the mixer (242) is also single.

  By using a low noise amplifier (221a, 221b) that outputs a single-ended signal and a single balance mixer (Single Balanced Mixer, 242), it has a selective path through which an external filter (F) can be used. In addition, when at least a part of the RF receiver (200) is a semiconductor chip, the number of pins (Pin) can be optimized.

  FIG. 2 is a block diagram of an RF receiver (200) according to a preferred embodiment of the present invention.

  As shown in FIG. 2, the RF receiver 200 according to a preferred embodiment of the present invention includes a matching and filtering unit 210, a low noise amplification unit 220, a switching unit 230, and a mixer unit 240. including.

  The matching and filtering unit 210 needs to be provided in each band, and serves to remove impedance matching and noise. Therefore, it is preferable that the matching and filter unit (210) is configured outside the semiconductor chip.

  The low noise amplifying unit 220 serves to amplify an RF (Radio Frequency) signal input via the matching and filter unit 210 and output the signal as one signal. For this purpose, the low noise amplification unit (220) of the present invention includes a plurality of low noise amplifiers (221a, 221b) and a third capacitor (C3).

  The outputs of the plurality of low noise amplifiers (221a, 221b) are combined into one and input from one end of the third capacitor (C3), and the third capacitor (C3) is the output of the plurality of low noise amplifiers (221a, 221b). The direct current component is blocked and output from the other end of the third capacitor (C3).

  Accordingly, each of the plurality of low noise amplifiers (221a, 221b) preferably outputs a single-ended signal.

  In the present invention, the outputs of a plurality of low noise amplifiers (221a, 221b) are connected so as to support a multiband simultaneously, and the circuits after the low noise amplifiers (221a, 221b) are shared and used. can do. Although two low noise amplifiers (221a, 221b) are shown in FIG. 2, a larger number of low noise amplifiers may be connected in parallel if necessary.

  The switch unit (230) inputs the output of the low noise amplifying unit (220) to the mixer unit (240) or the output of the low noise amplifying unit (220) via the external element (F). ). Specifically, the switch unit (230) inputs the output of the third capacitor (C3) to the mixer unit (240) or the output of the third capacitor (C3) via the external element (F). Input to (240). That is, the switch unit (230) can select the output path of the third capacitor (C3). Here, the external element (F) is preferably a filter.

  The mixer unit (240) includes at least one mixer (242) that converts the frequency using the output of the low noise amplification unit (220). The at least one mixer (242) is a single-balanced passive mixer (Single Balanced Passive Mixer).

  The low noise amplification unit (220), the switch unit (230), and the mixer unit (240) of the present invention are configured inside one semiconductor chip, and the external element (F) is an element located outside the one semiconductor chip. is there.

  Hereinafter, the low noise amplifiers (221a and 221b) included in the low noise amplification unit (220) of the present invention will be described in detail.

  FIG. 3 is a block diagram of an RF receiver (221a, 221b) according to a preferred embodiment of the present invention. As shown in FIG. 3, a low noise amplifier (221a, 221b) according to a preferred embodiment of the present invention includes a first part (P1) and a second part (P2).

  The first part (P1) serves to amplify the RF signal. Therefore, the second part (P2) outputs or does not output the output of the first part (P1). Specifically, the second part (P2) outputs the output of the first part (P1) when the corresponding low noise amplifier (221a, 221b) is in use among the plurality of low noise amplifiers (221a, 221b). When the other low noise amplifiers (221a, 221b) that are not the corresponding low noise amplifiers (221a, 221b) among the plurality of low noise amplifiers (221a, 221b) are in use, the first part (P1 ) Is not output.

  The first part (P1) includes a first transistor (T1) and a second transistor (T2), and the second part (P2) includes a 2-1 switch and a 2-2 switch. A 2-1 switch and a 2-2 switch are preferably connected between the first transistor (T1) and the second transistor (T2). Accordingly, the 2-1 switch and the 2-2 switch each include a third transistor (T3) and a fourth transistor (T4). That is, the low noise amplifier (221a, 221b) of the present invention is connected to the first transistor (T1), the third transistor (T3), the fourth transistor (T4), and the second transistor (T2) by cascode. Features.

  Each of the first transistor (T1), the second transistor (T2), the third transistor (T3), and the fourth transistor (T4) includes a first terminal, a second terminal, and a third terminal. Here, the first terminal means a gate terminal, the second terminal means a source terminal, and the third terminal means a drain terminal. However, depending on the situation, the second terminal may be a drain terminal and the third terminal may be a source terminal. Accordingly, in the present invention, the first transistor (T1) and the third transistor (T3) are preferably PMOS transistors, and the second transistor (T2) and the fourth transistor (T4) are preferably NMOS transistors.

  A signal (IN (221)) is input to the first terminal of the first transistor (T1) via the first capacitor (C1), and the second capacitor (C2) is input to the first terminal of the second transistor (T2). ), The same one signal (IN (221)) is input. The first capacitor and the second capacitor serve to protect the first terminal of the first transistor T1 and the first terminal of the fourth transistor T4 from electrostatic (Electrostatic Discharge, ESD), respectively. Accordingly, the first transistor T1 not only operates as a load resistance of the second transistor T2, but also serves to amplify the current of the second transistor T2 by reusing.

  The low noise amplifier (221a, 221b) of the present invention is configured to include a first resistor (R1). One end of the first resistor (R1) is connected to the first terminal of the first transistor (T1), and the other end of the first resistor (R1) is the output (OUT (221)) of the corresponding low noise amplifier (221a, 221b). Connected to. The first resistor (R1) is set to a value of 50Ω to 2kΩ and can be used as a self bias point of the first transistor (T1). Accordingly, the first resistor (R1) supplies a real component impedance for matching the input impedance, and can be used as a signal feedback path (Signal Feed-Back Path).

  The second transistor control signal (V2) is input to the first terminal of the second transistor (T2) of the present invention via the second resistor (R2) which is a high impedance element. The second resistor (R2) may be a resistor in the range of 20 kΩ to 50 kΩ, and serves to capture a DC bias point (DC Bias Point) of the second transistor (T2). Specifically, the bias point of the second transistor (T2) can be set by adjusting the resistance value of the second resistor (R2) little by little.

  Therefore, the third transistor control signal (V3) is input to the first terminal of the third transistor (T3) via the third resistor (R3) which is a high impedance element. The fourth transistor control signal (V4) is input to the first terminal of the fourth transistor (T4) via the fourth resistor (R4), which is a high impedance element. The third resistor (R3) and the fourth resistor (R4) preferably have a resistance value in the range of 20 kΩ to 50 kΩ.

  The third transistor (T3) and the fourth transistor (T4) are the first transistor (T1) when the corresponding low noise amplifier (221a, 221b) is in use among the plurality of low noise amplifiers (221a, 221b). And the output of the second transistor (T2) are output in an overlapping manner, and among the plurality of low noise amplifiers (221a, 221b), other low noise amplifiers (221a) that are not the corresponding low noise amplifiers (221a, 221b) 221b) is not used, the output of the first transistor (T1) and the output of the second transistor (T2) are not output. Specifically, when the corresponding low-noise amplifier (221a, 221b) is in use, the third transistor control signal (V3) is a high signal, and the fourth transistor control signal (V4) is low. ) It is desirable that a signal is input. Similarly, when the corresponding low-noise amplifier (221a, 221b) is not in use, it is preferable that the third transistor control signal (V3) is a low signal and the fourth transistor control signal (V4) is a high signal. .

  That is, in the present invention, when other low noise amplifiers (221a, 221b) are used, the third transistor (T3) and the fourth transistor (T4) used in the high gain (High Gain) are set to high impedance. Used as a switch. However, in this case, since the linearity of the low noise amplifiers (221a, 221b) may be reduced by the third transistor (T3) and the fourth transistor (T4), in order to solve this part, the third transistor The third resistor (R3) and the fourth resistor (R4) use high impedance resistors so that the gate voltage of the (T3) and the fourth transistor (T4) can go with respect to the source voltage.

  In order to improve the linearity by using a high impedance element for the gate, a switch can always be turned on (On by using a Cgs parasitic capacitor) so that the gate voltage can be followed by a large input signal. This is a method of improving the performance by operating only in the (State) state and preventing it from being momentarily disconnected in the off state (Off State).

  Below, the switch part (230) of this invention is demonstrated concretely.

  The switch unit 230 according to a preferred embodiment of the present invention includes a first switch SW1, a second switch SW2, and a third switch SW3. Accordingly, when the first switch (SW1) is turned on, the second switch (SW2) and the third switch (SW3) are turned off, and when the first switch (SW1) is turned off, the second switch (SW2) and the third switch (SW3) are preferably turned on.

  Specifically, the first switch (SW1) is disposed between the output of the third capacitor (C3) and the input of the mixer unit (240), and the second switch (SW2) is connected to the output of the third capacitor (C3). It arrange | positions between the one ends of an external element (F). Accordingly, the third switch (SW3) is disposed between the other end of the external element (F) and the input of the mixer unit (240). FIG. 4 is a circuit diagram of one embodiment of the first switch (SW1), the second switch (SW2), and the third switch (SW3).

  As shown in FIG. 4, each of the first switch (SW1), the second switch (SW2), and the third switch (SW3) of the present invention includes at least one basic switching component (U1, U2, U3).

  Specifically, the basic switching components (U1, U2, U3) are connected to the first terminal of one transistor (T5, T6, T7) and one transistor (T5, T6, T7). Component resistors (R (U11), R (U21), R (U31)), the second terminal of one transistor (T5, T6, T7) and the third terminal of one transistor (T5, T6, T7) It includes resistors for the second basic switching component (R (U12), R (U22), R (U32)) connected between them.

  Specifically, the first switch (SW1), the second switch (SW2), and the third switch (SW3) are the first basic switching component (U1), the second basic switching component (U2), and the third basic switching, respectively. Includes component (U3). Accordingly, the third terminal of the fifth transistor (T5) included in the first basic switching component (U1), the second terminal of the sixth transistor (T6) included in the second basic switching component (U2), and the third basic switching. The third terminals of the seventh transistor (T7) included in the component (U3) are connected to each other. Further, the fifth transistor (T5), the sixth transistor (T6), and the seventh transistor (T7) perform on / off operations, respectively. However, the same control signal (V (U1)) is input to the fifth transistor (T5) and the sixth transistor (T6), and the sixth transistor (T6) is turned on or off in the same manner as the fifth transistor (T5). The seventh transistor (T7) performs an on / off operation opposite to that of the fifth transistor (T5). That is, when the fifth transistor (T5) is turned on, the sixth transistor (T6) is turned on and the seventh transistor (T7) is turned off. Similarly, when the fifth transistor (T5) is turned off, the sixth transistor (T6) is turned off and the seventh transistor (T7) is turned on.

  Although only one basic switching component (U1, U2, U3) can be switched, in the present invention, by using three basic switching components (U1, U2, U3), each switch (SW1, SW2, It was possible to improve the isolation performance of SW3). The fifth transistor (T5) and the sixth transistor (T6) operate as a transistor for short-circuiting the corresponding path (Path). In the case of the seventh transistor (T7), the fifth transistor (T5) and It is necessary to control the control signals (V (U1), V (U2)) so as to perform an operation in a state opposite to that of the sixth transistor (T6). The first basic switching component resistors (R (U11), R (U21), R (U31)) are high impedance resistance values, similar to the third resistor (R3) and the fourth resistor (R4) in FIG. The resistance value for the second basic switching component (R (U12), R (U22), R (U32)) is controlled by the control signals (V (U1), V (U2)) using resistance values ranging from 20kΩ to 50kΩ. In order to control the signal, a DC bias point grounds the drain and the source node, and it is necessary to use a high-impedance element in order to enter an open state from the viewpoint of a small signal (Small Signal).

  Below, the mixer part (240) of this invention is demonstrated concretely.

  As shown in FIG. 2, the mixer unit (240) of the present invention includes a gain adjuster (ATT), a fourth capacitor (C4), a mixer (242), and a transimpedance amplifier (243). The mixer unit 240 of the present invention does not include a separate transimpedance amplifier, and uses the front-end low noise amplifiers 221a and 221b as the transimpedance amplifier.

  The gain adjuster (ATT) can adjust the gain of the mixer unit (240). The fourth capacitor (C4) is disposed at the rear end of the gain adjuster (ATT), thereby blocking the direct current component generated in the transimpedance amplifier (243), so that the fourth capacitor (C4) is connected to the mixer (242). ). The mixer (242) is a core of the mixer unit (240), and receives a local oscillation signal (LO) from the local oscillator and converts the frequency. In FIG. 2, the mixer (242) is shown by a single switch, but a plurality of mixers connected in parallel can be used depending on the number of phases used by the local oscillator.

  Therefore, even if the gain adjuster (ATT) and the fourth capacitor (C4) are shown in FIG. 2, the output signal of the switch unit (230) can be directly input to the mixer (242).

  According to the present invention, the low noise amplifier (221a, 221b) functions as a pre-amplifier of the mixer (242), thereby linearly changing between the low noise amplifier (221a, 221b) and the mixer (242). It was possible to minimize the factors that decrease the performance. Therefore, when a higher performance is required for an LTE jammer with an optional path (Path) that can use an external filter, the external filter assists the low noise amplifier (221a, 221b). An external filter can be used at the output that is not the input to minimize sensitivity degradation. Since it has a structure satisfying all the two parts, the output of the low-noise amplifier (221a, 221b) is single (single), one port (port) is used, and a single balance mixer (single balanced mixer) is used. This can be realized by assigning only one mixer input pin. In addition, all the outputs of the low noise amplifiers (221a, 221b) can be shared to reduce the number of mixers for multiband support.

  As described above, according to the multiband RF receiver (200) of the present invention, linearity is improved in a mobile TV tuner environment, the performance of IIP2 and IIP3 is improved, and required when connected to an external filter element. The number of semiconductor pins can be optimized.

200, RF receiver 210, matching and filter unit 220, low noise amplification unit 230, switch unit 240, mixer units 221a and 221b, low noise amplifier SW1, first switch SW2, second switch SW3, third switch ATT, gain Adjuster 242, mixer 243, transimpedance amplifier

Claims (19)

An RF receiver,
A low noise amplifier including a plurality of low noise amplifiers;
A mixer unit including at least one mixer for converting a frequency using an output of the low noise amplification unit;
An output of the low noise amplification unit is input to the mixer unit, and an output of the low noise amplification unit can be selected to be input to the mixer unit via an external element, and a switch unit,
Each of the plurality of low noise amplifiers outputs a single-ended signal.
The RF receiver according to claim 1, wherein the at least one mixer is a single balanced mixer.   Each of the plurality of low noise amplifiers has one output, and the low noise amplification unit further includes a third capacitor connected to the output of the plurality of low noise amplifiers. The RF receiver according to claim 1. The switch part is
A first switch disposed between the output of the third capacitor and the input of the mixer unit;
A second switch disposed between the output of the third capacitor and one end of the external element;
A third switch disposed between the other end of the external element and the input of the mixer unit;
The RF receiver according to claim 2, comprising: Each of the first switch, the second switch, and the third switch includes at least one basic switching component;
The basic switching component includes one transistor,
A first basic switching component resistor connected to a first terminal of the one transistor;
The RF receiver according to claim 3, further comprising a second basic switching component resistor connected between a second terminal of the one transistor and a third terminal of the one transistor. Each of the first switch, the second switch, and the third switch includes three basic switching components;
The three basic switching components are a first basic switching component, a second basic switching component, and a third basic switching component,
The third terminal of the fifth transistor included in the first basic switching component, the second terminal of the sixth transistor included in the second basic switching component, and the third terminal of the seventh transistor included in the third basic switching component Are connected to each other,
Each of the fifth transistor, the sixth transistor, and the seventh transistor performs an on / off operation,
The sixth transistor performs the same on or off operation as the fifth transistor,
The RF receiver according to claim 4, wherein the seventh transistor performs an on / off operation opposite to the fifth transistor. The low noise amplification unit, the switch unit, and the mixer unit are configured inside one semiconductor chip,
The RF receiver according to claim 2, wherein the external element is an element located outside the one semiconductor chip. Each of the plurality of low noise amplifiers is
A first portion for amplifying an RF signal;
A second part that outputs or does not output the output of the first part;
Including
The second portion outputs an output of the first portion when the corresponding low noise amplifier is in use among the plurality of low noise amplifiers, and the second portion outputs the corresponding low noise among the plurality of low noise amplifiers. 2. The RF receiver according to claim 1, wherein the output of the first portion is not output when another low-noise amplifier that is not an amplifier is in use. The first portion includes a first transistor and a second transistor;
The second part includes a 2-1 switch and a 2-2 switch,
The RF receiver according to claim 7, wherein the 2-1 switch and the 2-2 switch are connected between the first transistor and the second transistor. Wherein each of the first terminal of the second transistor and the first terminal of the first transistor via a first capacitor and a second capacitor, the signal is input, according to claim 8, characterized in that RF receiver. Each of the plurality of low noise amplifiers includes a first resistor;
The one end of the first resistor is connected to a first terminal of a first transistor, and the other end of the first resistor is connected to an output of the low noise amplifier. RF receiver. 9. The RF receiver according to claim 8 , wherein a second transistor control signal is input to the first terminal of the second transistor via a high impedance element. The 2-1 switch and the 2-2 switch each include a third transistor and a fourth transistor,
Each of the first terminal of the fourth transistor and the first terminal of said third transistor, a third transistor control signal and the fourth transistor control signal is input through the high impedance element, and wherein the The RF receiver according to claim 8. An RF receiver,
A plurality of low noise amplifiers;
A third capacitor connected to the outputs of the plurality of low noise amplifiers;
A first switch having one end connected to the other end of the third capacitor and turning on or off the output of the third capacitor;
A second switch having one end connected to the other end of the third capacitor and the other end connected to one end of the external element;
A third switch having one end connected to the other end of the external element,
Each of the plurality of low-noise amplifiers outputs a single-ended signal. When the first switch performs an on operation, the second switch and the third switch perform an off operation,
The RF receiver according to claim 13, wherein when the first switch performs an off operation, the second switch and the third switch perform an on operation. The RF receiver further includes at least one mixer that converts the frequency;
Each of the at least one mixer
14. The RF receiver according to claim 13, wherein signals from the other end of the first switch and the other end of the third switch connected to each other are input directly or via other elements. . The plurality of low noise amplifiers, the first switch, the second switch, the third switch, and the at least one mixer are configured in one semiconductor chip,
The RF receiver according to claim 15, wherein the external element is an external element located outside the one semiconductor chip. Each of the plurality of low noise amplifiers is
Including a first transistor, a third transistor, a fourth transistor, and a second transistor connected by a cascode,
The first transistor and the second transistor are used for signal amplification,
The third transistor and the fourth transistor output the output of the first transistor and the output of the second transistor in an overlapping manner when the low noise amplifier is in use among the plurality of low noise amplifiers. The output of the first transistor and the output of the second transistor are not output when another low noise amplifier that is not the low noise amplifier is in use among the plurality of low noise amplifiers. The RF receiver according to claim 13. The first terminal of the first transistor and the first terminal of the second transistor are respectively
The RF receiver according to claim 17, wherein a signal is input via the first capacitor and the second capacitor. Each of the plurality of low noise amplifiers includes a first resistor;
A third terminal of the third transistor and a third terminal of the fourth transistor are connected to perform output from the low noise amplifier;
One end of the first resistor is connected to the first terminal of the first transistor,
The RF receiver according to claim 17, wherein the other end of the first resistor is connected to an output of the low noise amplifier.