KR101727610B1 - Power amplifier for radio frequency - Google Patents

Abstract

A power amplifier for a radio frequency includes a main amplification unit including a first common source transistor and a first common gate transistor connected in a cascode structure, amplifying a single input signal, and outputting a carrier signal; an auxiliary amplification unit including a second common source transistor and a second common gate transistor connected in the cascode structure, and outputting a peak signal based on an intermediate output of the main amplification unit; and a coupling capacitor connected between a first node corresponding to an output terminal of the first common source transistor and a gate terminal of the second common source transistor and transmitting at least part of the intermediate output to the auxiliary amplification unit. Accordingly, the present invention can remarkably reduce the volume of the power amplifier for a radio frequency and can improve linearity in all output power areas.

Description

[0001] POWER AMPLIFIER FOR RADIO FREQUENCY [

The present invention relates to a power amplifier, and more particularly, to a power amplifier for radio frequency.

Recently, the wireless transmission / reception system has been rapidly developed. Accordingly, the wireless transceiver can support various wireless communication such as Long Term Evolution (LTE), wireless LAN (WLAN), Bluetooth and the like.

However, as the performance criteria required for wireless communications increase, it is difficult to integrate a single chip to reduce size and price. Currently, the wireless transceiver is integrated with bulk (Complementary Metal Oxide Semiconductor; CMOS) except for the power amplifier and the switch. The power amplifier and the switch are integrated using III-V compound semiconductors, And is implemented as a package.

In the case of CMOS transistors, it is somewhat difficult to produce a large output power required by the system due to the low breakdown voltage. To solve this problem, various methods such as a power combining power amplifier, a stacked power amplifier using a plurality of transistors, and a Doherty power amplifier have been studied. However, these methods are implemented by connecting two or more power amplifiers in parallel. Furthermore, when designing including an input divider and an output coupler for amplifying using a different signal, the size of the power amplifier That is, the volume) becomes large.

In addition, since these various power amplifiers are designed with the goal of improving the output power, additional linearity enhancement techniques are required to improve the linearity. This increases the complexity of the overall power amplifier design.

It is an object of the present invention to provide a power amplifier for radio frequency including a coupling capacitor connected between a main amplifier and an auxiliary amplifier for coupling an intermediate output of the main amplifier to the auxiliary amplifier.

It is another object of the present invention to provide a power amplifier for a radio frequency that amplifies and outputs a differential signal of an input signal.

It should be understood, however, that the present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit and scope of the invention.

In order to accomplish one object of the present invention, a power amplifier for a radio frequency according to embodiments of the present invention includes a first common source transistor connected in a cascode structure and a first common gate transistor, An auxiliary amplifier unit including a main amplifier unit for amplifying and outputting a carrier signal, a second common source transistor connected in a cascode structure and a second common gate transistor, and outputting a peak signal based on an intermediate output of the main amplifier unit; And a coupling capacitor coupled between a first node corresponding to an output terminal of the first common source transistor and a gate terminal of the second common source transistor to transfer at least a portion of the intermediate output to the auxiliary amplifier section .

According to one embodiment, when the signal of the first node exceeds a predetermined operating point, the signal provided to the gate terminal of the second common source transistor by the coupling of the coupling capacitor and the signal The second common source transistor may be turned on based on a bias voltage connected to the gate terminal of the source transistor, and the auxiliary amplifier section may operate.

According to one embodiment, the operating point can be controlled by the magnitude of the bias voltage and the size of the coupling capacitor.

According to an exemplary embodiment, the first common source transistor, the first common gate transistor, the second common source transistor, and the second common gate transistor may each be an NMOS transistor (N-channel Metal Oxide Semiconductor) have.

According to an embodiment, the first common source transistor, the first common gate transistor, the second common source transistor, and the second common gate transistor may each be a Complementary Metal Oxide Semiconductor (CMOS) transistor.

According to an embodiment, the main amplifying unit can operate in a class A or a class AB.

According to an embodiment, the power amplifier for radio frequency may further include an output coupling unit connected to the output terminal of the main amplifier unit and the output terminal of the auxiliary amplifier unit, and coupling the carrier signal and the peak signal in the same phase to each other have.

According to an embodiment, the main amplifying unit may further include a feedback unit that feeds back the gate voltage of the first common source transistor based on the output of the first common gate transistor.

According to one embodiment, the power amplifier for radio frequency includes a third common source transistor and a third common gate transistor connected in a cascode structure, and further auxiliary output means for outputting an additional peak signal based on the intermediate output of the auxiliary amplifier And a second common source transistor connected between a second node corresponding to an output terminal of the second common source transistor and a gate terminal of the third common source transistor to transmit a part of the output of the second common source transistor to the additional auxiliary amplifier section Lt; RTI ID = 0.0 > capacitors. ≪ / RTI >

In order to accomplish one object of the present invention, a power amplifier for a radio frequency according to embodiments of the present invention includes an input distributor for distributing a single input signal to a first differential signal and a second differential signal, a cascode structure A first common amplifying section including a first common source transistor and a first common gate transistor connected to each other and outputting a first carrier signal by amplifying the first differential signal, a second common source transistor connected in a cascode structure, A second main amplifier unit including a common gate transistor for amplifying the second differential signal and outputting a second carrier signal, a third common source transistor and a third common gate transistor connected in a cascode structure, A first auxiliary amplifier unit for outputting a first peak signal based on an intermediate output of the first main amplifier unit, A first coupling capacitor connected between a first node corresponding to the first common amplifying part and a gate terminal of the third common source transistor and transmitting at least a part of the intermediate output of the first main amplifying part to the first auxiliary amplifying part, A second auxiliary amplifier unit including a fourth common source transistor and a fourth common gate transistor connected in a structure and outputting a second peak signal based on an intermediate output of the second main amplifier unit, And a second coupling capacitor connected between a second node corresponding to the second common amplifying part and a gate terminal of the fourth common source transistor and transmitting at least a part of the intermediate output of the second main amplifying part to the second auxiliary amplifying part can do.

According to an embodiment, when the signal of the first node exceeds a predetermined operating point, a signal provided to the gate terminal of the third common source transistor by coupling of the first coupling capacitor, The second common source transistor may be turned on based on a bias voltage connected to the gate terminal of the third common source transistor, and the first auxiliary amplifier section may operate.

According to one embodiment, when the signal of the second node exceeds a predetermined operating point, a signal provided to the gate terminal of the fourth common source transistor by coupling of the second coupling capacitor, The fourth common source transistor may be turned on based on a bias voltage connected to the gate terminal of the fourth common source transistor, and the second auxiliary amplifier section may operate.

According to an embodiment, the power amplifier for radio frequency includes an output terminal of the first main amplification unit and an output terminal of the second main amplification unit to combine the first carrier signal and the second carrier signal to generate a combined carrier signal, And an output terminal connected to the output terminal of the first auxiliary amplifier and the output terminal of the second auxiliary amplifier so as to generate a coupled peak signal by combining the first peak signal and the second peak signal, 2 output coupling unit.

According to an embodiment, the first output coupling unit and the second output coupling unit may combine the phase of the combined carrier signal and the phase of the combined peak signal, respectively, in the same phase.

The RF power amplifier according to embodiments of the present invention controls the operation of the auxiliary amplifier while distributing the power of the RF input signal using the power coupling of the coupling capacitor so that the volume of the RF power amplifier is greatly reduced . That is, in order to distribute signals provided to the main amplifying unit and the auxiliary amplifying unit, an input distributor composed of a transformer and other passive elements to be provided in a conventional power amplifier may be eliminated.

In addition, the RF power amplifier improves the output efficiency in the low output power (i.e., the first driving region) by adaptively operating the auxiliary amplifier by coupling of the coupling capacitor (that is, , The magnitude of the maximum output power is increased, and the linearity in all the output power regions is improved (that is, the main and auxiliary amplifiers operate together).

However, the effects of the present invention are not limited to the effects described above, and may be variously extended without departing from the spirit and scope of the present invention.

1 is a diagram illustrating a power amplifier for a radio frequency according to embodiments of the present invention.
2 is a diagram showing an example of a power amplifier for radio frequency of FIG.
3 is a graph showing power addition efficiency of the power amplifier for radio frequency of FIG.
4 is a graph showing the amplification gain of the power amplifier for radio frequency in Fig.
5A is a graph for linearity analysis of the output of the power amplifier for radio frequency of FIG.
FIG. 5B is a graph comparing the output of the power amplifier for radio frequency of FIG. 2 with the linearity of the output of the conventional power amplifier.
6 is a diagram showing another example of the power amplifier for radio frequency of FIG.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a diagram illustrating a power amplifier for a radio frequency according to embodiments of the present invention.

Referring to FIG. 1, a power amplifier 100 for radio frequency includes a main amplifier 120. And a coupling capacitor C for electrically connecting the auxiliary amplifier unit 140 and the main amplifier unit 120 to the auxiliary amplifier unit 140. The power amplifier 100 for radio frequency may further include an output coupling unit 160 connected to an output terminal of the main amplifier unit 120 and an output terminal of the auxiliary amplifier unit 140.

The main amplifying unit 120 may be disposed between the input terminal RF_IN and the output coupling unit 160 to which the RF input signal is applied. The radio frequency input signal may be provided as a single input signal. The main amplifying unit 120 may include a first common source transistor M11 and a first common gate transistor M12 connected in a cascode structure. The main amplifying unit 120 may amplify the RF input signal and output a carrier signal. The first common source transistor M11 may include a gate terminal receiving the input signal and a predetermined first bias voltage VG1, a source terminal connected to the ground, and a drain terminal connected to the first node N1 have. The first common gate transistor M12 includes a gate terminal receiving a predetermined second bias voltage VG2, a source terminal connected to the first node N1, and a drain terminal coupled to the output coupling section 160 .

The switching of the first common source transistor M11 may be controlled by the radio frequency input signal and the first bias voltage VG1. The RF input signal may be amplified twice through the first common source transistor M11 and the first common gate capacitor coupling condition transistor M12. A signal amplified while passing through the first common source transistor M11 can be transferred to the source terminal of the first common gate transistor M12 and the coupling capacitor C. The amplified signal may be amplified by the carrier signal while passing through the first common gate transistor M12, and may be provided to the output coupler 160. [ The first common gate transistor M12 may be controlled by a voltage difference between the second bias voltage VG2 and the first node N1.

When the power of the RF input signal is lower than a predetermined threshold value, only the main amplification unit 120 performs the amplification operation and the auxiliary amplification unit 140 does not operate. That is, the above case means that the output power of the power amplifier 100 is smaller than a predetermined value (in the case of low output power). Hereinafter, the power range in which only the main amplification unit 120 performs the amplification operation is referred to as a first driving region, and the power range in which the main amplification unit 120 and the auxiliary amplification unit 140 simultaneously perform the amplification operation is referred to as a second Driving region.

In one embodiment, the main amplifier 120 may operate in Class A or Class AB. Accordingly, the main amplifier 120 can output a signal waveform of class A, class AB, or class B, which can have high linearity. In addition, since only the main amplifier 120 participates in the amplification operation in a power range lower than the threshold value (i.e., the first driving range), the size of the input signal can be reduced, It is possible to improve the output efficiency.

The auxiliary amplifier 140 may include a second common source transistor M21 and a second common gate transistor M22 connected in a cascode structure. The auxiliary amplifier unit 140 may output a peak signal based on the intermediate output of the main amplifier unit 120. Here, the intermediate output of the main amplifying unit 120 corresponds to the signal amplified by the first common source transistor M11, and the intermediate output signal may correspond to the signal of the first node N1.

The second common source transistor M21 includes a gate terminal receiving a signal coupled by the coupling capacitor C and a predetermined third bias voltage VG2, a source terminal connected to the ground, and a second common gate transistor And a drain terminal connected to the source terminal of the second transistor M22. The second common gate transistor M12 is connected to the gate terminal receiving the predetermined fourth bias voltage VG4, the source terminal connected to the drain terminal of the second common source transistor M21, and the output coupling section 160 And a source terminal connected to the drain terminal. That is, the second common source transistor M21 does not receive the RF input signal directly.

The switching of the second common source transistor M21 can be controlled by at least a part of the intermediate output transmitted from the coupling capacitor C and the third bias voltage VG3. Therefore, when the power of the RF input signal is smaller than the threshold value (the first driving region), that is, when the output power of the power amplifier 100 is smaller than a preset predetermined value, The amplitude of the signal of the auxiliary amplifier 140 is relatively small, so that the auxiliary amplifier 140 does not operate. However, when the RF input signal is greater than or equal to the threshold value (the second driving region), the auxiliary amplifier 140 operates and can output the peak signal. In one embodiment, the auxiliary amplifier 140 operates in class C and can output the peak waveform corresponding to class C. [

In one embodiment, the first common source transistor M11, the first common gate transistor M12, the second common source transistor M21, and the second common gate transistor M22 are complementary metal oxide semiconductor (CMOS) ; CMOS) transistors. In another embodiment, the first common source transistor M11, the first common gate transistor M12, the second common source transistor M21, and the second common gate transistor M22 are each an N- Oxide Semiconductor (NMOS) transistors.

The coupling capacitor C may be connected between the first node N1 corresponding to the output terminal of the first common source transistor M11 and the gate terminal G1 of the second common source transistor M21. That is, the coupling capacitor C can electrically connect the main amplifying unit 120 and the auxiliary amplifying unit 140. Here, the coupling capacitor C may deliver at least a part of the intermediate output (that is, the signal of the first node N1) to the auxiliary amplifier unit 140. [ The coupling capacitor C is coupled based on the swing of the signal of the first node N1 and the coupling provides a predetermined signal to the gate terminal G1 of the second common source transistor M21 .

In one embodiment, if the signal at the first node N1 exceeds a predetermined operating point, it is coupled to the gate terminal G1 of the second common source transistor M21 by coupling of the coupling capacitor Cl The second common source transistor M21 is turned on based on the above-described signal and the third bias voltage VG3 connected to the gate terminal G1 of the second common source transistor M21, and the auxiliary amplifier 140 Can operate. Accordingly, the auxiliary amplifier 140 operates only when the RF input signal has a predetermined power level or more, and can output the peak signal. In one embodiment, the operating point may be controlled by the magnitude of the third bias voltage VG3 and the size of the coupling capacitor C. [ For example, as the third bias voltage VG3 increases, the operating point is lowered, and the auxiliary amplifier unit 140 can operate even when the amplitude of the RF input signal is small.

The output coupling unit 160 may be connected to the output terminal of the main amplifier unit 120 and the output terminal of the auxiliary amplifier unit 140 to couple the carrier signal and the peak signal in the same phase. In one embodiment, the output combining unit 160 may include a matching network that performs impedance matching of the carrier signal and the peak signal. For example, the matching network may include a combination of an inductor and a capacitor, and includes a balun connected to the output terminal of the main amplifying unit 120 and the output terminal of the auxiliary amplifying unit 140, respectively can do. Accordingly, the carrier signal and the peak signal output from the second driving region can be coupled in phase with each other. The combined output signal may be output to an external circuit via a radio frequency output terminal RF_OUT.

In one embodiment, the main amplifying unit 120 may further include a feedback unit for feeding back the gate voltage of the first common source transistor M11 based on the output of the first common gate transistor M12. For example, the feedback section may include a resistor and a capacitor connected between the drain terminal of the first common gate transistor M12 and the gate terminal of the first common source transistor M11. The auxiliary amplifier unit 140 may further include a feedback unit of the same type as the feedback unit.

As described above, the RF power amplifier 100 according to the embodiments of the present invention distributes the power of the RF input signal using the power coupling of the coupling capacitor C, The volume of the radio frequency power amplifier 100 can be greatly reduced. That is, in order to distribute the signals provided to the main amplifying unit 120 and the auxiliary amplifying unit 140, an input distributor composed of a transformer and other passive elements to be provided in the conventional power amplifier can be eliminated. Further, the radio frequency power amplifier 100 can improve the output efficiency in the low output power (i.e., the first driving region), increase the maximum output power, and improve the linearity in the entire output region have.

2 is a diagram showing an example of a power amplifier for radio frequency of FIG.

The power amplifier for radio frequency according to the present embodiment is substantially the same as or similar to the configuration and operation of the driving circuit for radio frequency according to FIG. 1 except for a configuration in which a radio frequency input signal is added by being divided and input in the form of a differential signal , The same reference numerals are used for the same or corresponding constituent elements, and redundant explanations are omitted.

2, the RF power amplifier 200 includes an input distribution unit 210, a first main amplification unit 220, a second main amplification unit 230, a first auxiliary amplification unit 240, A first coupling capacitor C1 electrically connecting the first main amplifier 210 and the first auxiliary amplifier 240 to each other, a second main amplifier 230 connected to the second main amplifier 230, And a second coupling capacitor C1 electrically connecting the auxiliary amplifier unit 250. [ The power amplifier 200 for radio frequency includes a first output coupling unit 262 and a second output coupling unit 264 for re-coupling the distributed input signals (or the amplified signals of the distributed input signals) And may further include a coupling portion 260.

The input distributor 210 may divide a single RF input signal into a first differential signal and a second differential signal. For example, the first differential signal and the second differential signal may be differential signals having a phase difference of 90 degrees. In one embodiment, the input distributor 210 may include a matching circuit (or balun) for modulating the phase of the radio frequency input signal. The input divider generates a differential signal of the RF input signal, and the first and second differential signals may have a phase difference of 90 degrees.

The first main amplifying unit 220 may receive the first differential signal. The first main amplifying unit 220 may include a first common source transistor M11 and a first common gate transistor M12 connected in a cascode structure. The main amplifying unit 120 may amplify the first differential signal and output a first carrier signal. The switching of the first common source transistor M11 can be controlled by the first differential signal and the first bias voltage VG1. The first differential signal can be amplified twice through the first common source transistor M11 and the first common gate capacitor coupling condition transistor M12.

In one embodiment, the first main amplifying unit 220 further includes a feedback unit 222 that feeds back the gate voltage of the first common source transistor M11 based on the output of the first common gate transistor M12 . For example, the feedback section 222 may include a resistor and a capacitor connected between the drain terminal of the first common gate transistor M12 and the gate terminal of the first common source transistor M11. The first common source transistor M11 includes a gate terminal receiving the first differential signal and a predetermined first bias voltage VG1, a source terminal connected to the ground, and a drain terminal connected to the first node N1 can do. The first common gate transistor M12 includes a gate terminal receiving a predetermined second bias voltage VG2, a source terminal connected to the first node N1, and a drain terminal coupled to the output coupling section 262 .

And the second main amplifying unit 230 may receive the second differential signal. The second main amplifying unit 230 may include a second common source transistor M13 and a second common gate transistor M14 connected in a cascode structure. The second common source transistor M13 includes a gate terminal receiving the second differential signal and the first bias voltage VG1, a source terminal connected to the ground, and a drain terminal connected to the second node N2 . The second common gate transistor M14 includes a gate terminal commonly receiving the second bias voltage VG2, a source terminal coupled to the second node N2, and a drain terminal coupled to the output coupling section 262 . The second main amplifying unit 230 may amplify the second differential signal and output a second carrier signal. Since the configuration and operation of the first and second main amplifying units 220 and 230 are substantially the same as those of the main amplifying unit 120 of FIG. 1, a description thereof will be omitted.

In one embodiment, the first and second main amplifiers 120 and 140 may operate in Class A or Class AB.

The first auxiliary amplifier 240 may include a third common source transistor M21 and a third common gate transistor M22 connected in a cascode structure. The first auxiliary amplifier unit 240 may output a peak signal based on the intermediate output of the first main amplifier unit 220. Here, the intermediate output of the first main amplifying unit 220 corresponds to the signal amplified by the first common source transistor M11, and the intermediate output signal may correspond to the signal of the first node N1 . The third common source transistor M21 does not receive the RF input signal directly. The first auxiliary amplifying unit 250 may output the first peak signal in the second driving region.

The second auxiliary amplifier unit 250 may include a fourth common source transistor M23 and a fourth common gate transistor M24 connected in a cascode structure. The configuration and operation of the first and second auxiliary amplifying units 240 and 250 are substantially the same as those of the auxiliary amplifying unit 140 shown in FIG. 1, and a description thereof will be omitted. The first auxiliary amplifying unit 250 may output the second peak signal in the second driving region.

Each of the main amplifying units 220 and 230 and the auxiliary amplifying units 240 and 250 may further include a feedback circuit disposed at the same position.

The first coupling capacitor C1 may be connected between the first node N1 and the gate terminal G1 of the third common source transistor M21. That is, the first coupling capacitor C1 may electrically connect the first main amplification unit 220 and the first auxiliary amplification unit 240. The operation of the first auxiliary amplifier 240 is controlled by at least a part of the intermediate output of the first main amplifier 220 and the third bias voltage VG3 transmitted from the first coupling capacitor C1 .

Likewise, the second coupling capacitor C2 may be connected between the second node N2 and the gate terminal G2 of the fourth common source transistor M23. That is, the second coupling capacitor C2 may electrically couple the second main amplification unit 230 and the second auxiliary amplification unit 250 to each other. The operation of the second auxiliary amplifier 250 is controlled by at least a part of the intermediate output of the second main amplifier 230 from the second coupling capacitor C2 and the third bias voltage VG3 .

In one embodiment, when the signal at the first node N1 (i.e., the intermediate output of the first main amplifying unit 220) exceeds a predetermined operating point, a couple of first coupling capacitors C1 Based on the signal supplied to the gate terminal G1 of the third common source transistor M21 by the ring and the third bias voltage VG3 connected to the gate terminal G1 of the third common source transistor M21, The common source transistor M21 may be turned on and the first auxiliary amplifier 240 may operate. Also, in one embodiment, when the signal at the second node N2 (i.e., the intermediate output of the second main amplifier 230) exceeds a predetermined operating point, the second coupling capacitor C2, On the basis of the signal supplied to the gate terminal G2 of the fourth common source transistor M23 and the third bias voltage VG3 connected to the gate terminal G2 of the fourth common source transistor M23 The fourth common source transistor M23 may be turned on and the second auxiliary amplifier 250 may operate. In one embodiment, the operating point may be controlled by the magnitude of the third bias voltage VG3 and the size of the coupling capacitors C1, C2.

The first output coupling unit 262 may be connected to the output terminal of the first main amplifier unit 220 and the output terminal of the second main amplifier unit 230. The first output coupling unit 262 may combine the first carrier signal and the second carrier signal to generate a combined carrier signal. In one embodiment, the first output coupling portion 262 may include a matching circuit (e.g., a balun) that makes the phase of the first carrier signal and the second carrier signal the same. The first output coupling unit 262 may adjust the phase of the combined carrier signal such that the phase of the combined carrier signal is equal to the phase of the combined peak signal.

The second output coupling unit 264 may be connected to the output terminal of the first auxiliary amplifier unit 240 and the output terminal of the second auxiliary amplifier unit 250. The second output coupling unit 264 may combine the first peak signal and the second peak signal to generate a combined peak signal. In one embodiment, the second output coupling portion 264 may comprise a matching circuit (e. G., A balun) that makes the phase of the first peak signal and the second peak signal the same. The second output coupling unit 264 may adjust the phase of the coupling peak signal so that the phase of the coupling peak signal is the same as the phase of the coupling peak signal. In one embodiment, the coupling portion including the first and second output coupling portions 162 and 164 may include a matching network that performs impedance matching of the combined carrier signal and the coupling peak signal. Accordingly, the combined carrier signal and the combined peak signal output from the second driving region can be coupled with the same phase. The combined output signal may be output to an external circuit via a radio frequency output terminal RF_OUT.

3 is a graph showing power addition efficiency of the power amplifier for radio frequency of FIG.

FIG. 3 shows a comparative example of the power addition efficiency between the power amplifier for radio frequency (CCPA) and the conventional power amplifier (CONV_PA) in the first driving region. Here, the first driving region means a power range in which only the main amplifying unit of the power amplifier for the radio frequency (CCPA) performs the amplifying operation, and the output power of the power amplifier for the radio frequency (CCPA) It can mean a small power range.

Referring to FIG. 3, a power amplifier (CCPA) for a radio frequency according to an embodiment of the present invention may have a higher power added efficiency (PAE) than a conventional general power amplifier (CONV_PA).

The conventional power amplifier (CON_PA) is a class AB power amplifier operating in class AB. In one embodiment, the main amplifier of the power amplifier for radio frequency (CCPA) may operate in Class A or Class AB. In the first driving region, since only the main amplifier participates in the amplification operation, the input signal (or the input current) provided to the power amplifier for the radio frequency (CCPA) can be reduced have. Therefore, as shown in Fig. 3, the power addition efficiency in the low output power region, i.e., the first drive region, can be increased as compared with the conventional power amplifier CONV_PA.

4 is a graph showing the amplification gain of the power amplifier for radio frequency in Fig.

Referring to FIG. 4, the amplification gain can be changed by the operation of the main amplifier and the auxiliary amplifier included in the power amplifier for radio frequency. 4 shows the amplification gain when only the main amplification unit performs the amplification operation, and the solid line graph of FIG. 4 shows the amplification gain when the main amplification unit and the auxiliary amplification unit perform the amplification operation at the same time .

4A is a graph comparing amplification gains, and FIG. 4B is a graph comparing power addition efficiencies. As shown in FIG. 4A, when the main amplification unit and the auxiliary amplification unit perform amplification together in an output region having a predetermined output power or more, a larger power is output than when the main amplification unit alone performs amplification can do. That is, the maximum output value when the main amplification unit and the auxiliary amplification unit perform amplification together can be determined to be larger than the maximum output value when only the main amplification unit performs amplification.

Wherein when the maximum output value when the main amplification unit and the auxiliary amplification unit perform amplification together and the maximum output value when only the main amplification unit performs amplification are respectively determined, It is possible to perform a backoff operation for lowering the level of the input signal input to the power amplifier. In this case, as shown in FIG. 4B, the amplification efficiency by the back-off operation between the case where the main amplification unit and the auxiliary amplification unit perform amplification together with the case where only the main amplification unit performs amplification That is, the power addition efficiency). Therefore, the power amplifier for the radio frequency in which the main amplification unit and the auxiliary amplification unit perform amplification can maintain the high amplification efficiency and increase the maximum value of the output power.

FIG. 5A is a graph for analyzing the linearity of the output of the power amplifier for the radio frequency of FIG. 2, and FIG. 5B is a graph comparing the output of the power amplifier for the radio frequency of FIG. 2 and the linearity of the output of the conventional power amplifier.

5A and 5B, the linearity of the power amplifier for the radio frequency can be analyzed by the magnitude of a signal input to the common source transistor included in the power amplifier for radio frequency and the mutual conductance of the common source transistor have.

The change in the third current component of the drain current of the common source transistor according to the change in the gate-source voltage of the common source transistor may vary depending on the operation of the main amplifier and the auxiliary amplifier. For example, as shown in FIG. 5A, when only the main amplifying unit performs amplification (shown by the MAIN graph in FIG. 5A) and only the auxiliary amplifying unit performs amplification 5A), when the main and auxiliary amplifying units perform amplification together, the third and fourth current components (FIG. 5A and FIG. 5A) That is, the mutual conductance of the common source transistor) is larger.

5B is a graph showing an analysis of the slope (i.e., derivative value) of the tertiary current component (i.e., IDS3 in FIG. 5B). In the graph of Fig. 5B, if the derivative of the third current component corresponds to zero, this means that the linearity of the power amplifier is improved. That is, as shown in FIG. 5B, the conventional power amplifier CONV_PA does not have a portion where the differential value of the third-order current component is 0 as the input signal increases, but the power according to the embodiments of the present invention The amplifier (CCPA) has zero at the two input signal points. As a result, the power amplifier (CCPA) according to embodiments of the present invention can have improved linearity than the conventional power amplifier (CONV_PA).

6 is a diagram showing another example of the power amplifier for radio frequency of FIG.

Since the power amplifier for radio frequency according to the present embodiment is substantially the same as or similar to the configuration and operation of the driving circuit for radio frequency according to FIG. 1 except for the configuration further including a plurality of additional auxiliary amplifiers, The same reference numerals are used for the constituents, and redundant explanations are omitted.

6, a power amplifier 300 for a radio frequency includes a main amplifier 120, an auxiliary amplifier 140, and a coupling capacitor (not shown) electrically connecting the main amplifier 120 and the auxiliary amplifier 140, (C). The power amplifier 300 for radio frequency may further include additional coupling capacitors C2 and C3 and additional auxiliary amplifiers 142 and 143 connected to the auxiliary amplifier 140 in a dependent manner. The RF power amplifier 300 further includes an output coupling unit 160A connected to the output terminal of the main amplifier unit 120, the output terminal of the auxiliary amplifier unit 140, and the additional auxiliary amplifier units 142 and 144 can do.

The coupling capacitors C2 and C3 electrically connect the auxiliary auxiliary amplifying units 142 and 144 to the auxiliary auxiliary amplifying units 142 and 144, respectively, The number is not limited thereto. For example, the additional auxiliary amplifier unit may have a structure in which one or more auxiliary amplifier units are connected in a dependent manner.

The main amplifying unit 120 may be disposed between the input terminal RF_IN and the output coupling unit 160 to which the RF input signal is applied. The radio frequency input signal may be provided as a single input signal. When the RF input signal is inputted as a differential signal, the main amplifier 120 and the auxiliary amplifiers 140, 142 and 144 may have substantially the same structure as that of FIG. The main amplifying unit 120 may include a first common source transistor M11 and a first common gate transistor M12 connected in a cascode structure. The main amplifying unit 120 may amplify the RF input signal and output a carrier signal.

The auxiliary amplifier 140 may include a second common source transistor M21 and a second common gate transistor M22 connected in a cascode structure. The auxiliary amplifier unit 140 may output a peak signal according to the magnitude of the output power based on the intermediate output of the main amplifier unit 120.

The coupling capacitor C1 may be connected between the first node N1 corresponding to the output terminal of the first common source transistor M11 and the gate terminal G1 of the second common source transistor M21. That is, the coupling capacitor C1 can electrically connect the main amplifying unit 120 and the auxiliary amplifying unit 140.

The first additional auxiliary amplifier 142 and the second additional auxiliary amplifier 144 may also have substantially the same structure as the auxiliary amplifier 140. Accordingly, the first additional auxiliary amplifier 142 and the second additional auxiliary amplifier 144 can also output additional additional peak signals, respectively.

The first additional coupling capacitor C2 and the second additional coupling capacitor C3 are also connected to the first additional auxiliary amplifier 142 and the second auxiliary auxiliary amplifier 144 in the same manner as the coupling capacitor C1 And can be electrically connected to the auxiliary amplifying unit 140.

However, since the operation and configuration of the amplification units and the coupling capacitors have been described in detail with reference to FIGS. 1 to 3, a description thereof will be omitted.

The output coupling unit 160A is connected to the output terminal of the main amplifier unit 120, the output terminal of the auxiliary amplifier unit 140 and the output terminals of the additional auxiliary amplifier units 142 and 144, Signal, and the additional peak signals in the same phase with each other. The combined output signal may be output to an external circuit via a radio frequency output terminal RF_OUT.

As described above, the radio frequency power amplifier 300 controls the operation of the auxiliary amplifier 140 while distributing the power of the radio frequency input signal using the power coupling of the coupling capacitor, 100) can be greatly reduced. That is, in order to distribute the signals provided to the main amplifying unit 120 and the auxiliary amplifying unit 140, an input distributor composed of a transformer and other passive elements to be provided in the conventional power amplifier can be eliminated. The RF power amplifier 100 selectively operates the auxiliary amplifying unit 140 (and the additional auxiliary amplifying units 142 and 144) by coupling of the coupling capacitors C1, C2 and C3, The output efficiency in the output power (i.e., the first drive region) is improved, the magnitude of the maximum output power is increased, and the linearity in the entire region of the output can be improved.

The present invention can be applied to various wireless transmission / reception systems including a power amplifier for radio frequency.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.

100, 200, 300: Power amplifier for radio frequency
120, 220, 230: main amplification unit 140, 240, 250:
160, 262, 264: output coupling unit 210: input distribution unit
222:

Claims (13)

A main amplifier unit including a first common source transistor and a first common gate transistor connected in a cascode structure and amplifying a single input signal and outputting a carrier signal;
An auxiliary amplifier unit including a second common source transistor and a second common gate transistor connected in a cascode structure and outputting a peak signal based on an intermediate output of the main amplifier unit;
A coupling capacitor coupled between a first node corresponding to an output terminal of the first common source transistor and a gate terminal of the second common source transistor to transfer at least a portion of the intermediate output to the auxiliary amplifier; And
And an output coupling unit connected to the output terminal of the main amplifying unit and the output terminal of the auxiliary amplifying unit to combine the carrier signal and the peak signal in the same phase,
The main amplifier
And a resistor and a capacitor connected in series between the output terminal of the main amplifier and the gate terminal of the first common source transistor so that the gate voltage of the first common source transistor is set to Further comprising a first feedback section for feedback,
The auxiliary amplifier
And a resistor and a capacitor connected in series between the output terminal of the auxiliary amplifier and the gate terminal of the second common source transistor so that the gate voltage of the second common source transistor is set to Further comprising a second feedback section for feeding back the feedback signal. 2. The method of claim 1, further comprising: coupling a signal provided to the gate terminal of the second common source transistor by coupling of the coupling capacitor when the signal at the first node exceeds a predetermined operating point, The second common source transistor is turned on based on a bias voltage connected to the gate terminal of the source transistor, and the auxiliary amplifier section operates. 3. The power amplifier according to claim 2, wherein the operating point is controlled by a magnitude of the bias voltage and a size of the coupling capacitor. The method of claim 1, wherein the first common source transistor, the first common gate transistor, the second common source transistor, and the second common gate transistor are NMOS transistors or NMOS transistors, respectively. Wherein the power amplifier is a Complementary Metal Oxide Semiconductor (CMOS) transistor. The power amplifier according to claim 1, wherein the main amplifier operates in a class A or a class AB. delete delete The method according to claim 1,
An additional auxiliary amplifier unit including a third common source transistor connected in a cascode structure and a third common gate transistor and outputting an additional peak signal based on an intermediate output of the auxiliary amplifier unit; And
An additional couple coupled between a second node corresponding to an output terminal of the second common source transistor and a gate terminal of the third common source transistor to deliver a portion of the output of the second common source transistor to the additional auxiliary amplifier section, Further comprising a ring capacitor. An input distribution unit for distributing a single input signal to a first differential signal and a second differential signal;
A first main amplifying unit including a first common source transistor and a first common gate transistor connected in a cascode structure and amplifying the first differential signal and outputting a first carrier signal;
A second main amplifier unit including a second common source transistor connected in a cascode structure and a second common gate transistor, for amplifying the second differential signal and outputting a second carrier signal;
A first auxiliary amplifier unit including a third common source transistor connected in a cascode structure and a third common gate transistor and outputting a first peak signal based on an intermediate output of the first main amplifier unit;
And a second common amplifying part connected between a first node corresponding to an output terminal of the first common source transistor and a gate terminal of the third common source transistor to transmit at least a part of the intermediate output of the first main amplifying part to the first auxiliary amplifying part A first coupling capacitor;
A second auxiliary amplifier unit including a fourth common source transistor and a fourth common gate transistor connected in a cascode structure and outputting a second peak signal based on an intermediate output of the second main amplifier unit;
And a second common amplifying part connected between a second node corresponding to an output terminal of the second common source transistor and a gate terminal of the fourth common source transistor to transmit at least part of the intermediate output of the second main amplifying part to the second auxiliary amplifying part A second coupling capacitor;
A first output coupling unit connected to an output terminal of the first main amplification unit and an output terminal of the second main amplification unit to combine the first carrier signal and the second carrier signal to generate a combined carrier signal; And
And a second output coupling unit coupled to the output terminal of the first auxiliary amplifier unit and the output terminal of the second auxiliary amplifier unit to combine the first peak signal and the second peak signal to generate a combined peak signal,
Wherein the first main amplifying unit further comprises a first feedback unit for feeding back the gate voltage of the first common source transistor using the output of the first common gate transistor,
The second main amplifying unit further includes a second feedback unit for feeding back the gate voltage of the second common source transistor using the output of the second common gate transistor,
Wherein the first auxiliary amplifier unit further includes a third feedback unit for feeding back the gate voltage of the third common source transistor using the output of the third common gate transistor,
Wherein the second auxiliary amplifier unit further comprises a fourth feedback unit for feeding back the gate voltage of the fourth common source transistor by using the output of the fourth common gate transistor. 10. The method of claim 9, further comprising: when a signal at the first node exceeds a predetermined operating point, a signal provided to the gate terminal of the third common source transistor by coupling of the first coupling capacitor, And the second common source transistor is turned on based on a bias voltage connected to the gate terminal of the third common source transistor, and the first auxiliary amplifier section operates. 10. The method of claim 9, further comprising: when a signal at the second node exceeds a predetermined operating point, a signal provided to the gate terminal of the fourth common source transistor by coupling of the second coupling capacitor, The fourth common source transistor is turned on based on a bias voltage connected to the gate terminal of the fourth common source transistor, and the second auxiliary amplifier section operates. delete 10. The receiver of claim 9, wherein the first output coupling unit and the second output coupling unit respectively adjust the phase of the combined carrier signal and the phase of the combined peak signal, amplifier.

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