KR20120059339A - High-efficiency power amplifier with multiple power mode - Google Patents

Abstract

PURPOSE: A high efficiency power amplifier is provided to optimize output impedances of each amplifier by constituting an impedance matching network with a capacitor. CONSTITUTION: A multi mode power amplifier(100) amplifies a received radio frequency signal. An input impedance matching network(110) transmits the radio frequency signal to first and second amplification units(119,124). The first and the second amplification unit amplify the radio frequency signal. The first amplification unit includes an impedance matching network A-1(120) and a first amplification unit(150). The second amplification unit includes an impedance matching network A-2(125) and a second amplification unit(155). An output impedance matching network(140) transmits an amplified signal to a load. A control device(170) activates the first amplification unit and the second amplification unit.

Description

High-efficiency power amplifier with multi-mode support {HIGH-EFFICIENCY POWER AMPLIFIER WITH MULTIPLE POWER MODE}

Devices (eg, cellular phones) used in wireless communication services are increasingly required to be smaller and lighter. This means that the size of batteries built into these devices is also becoming smaller. In connection with this, it is desired to extend the talkable time by one charging of the radio communication apparatus. As such, it is desirable to provide power to a wireless communication device for a longer time while reducing the size of the battery.

Multi-mode power amplifiers can switch between high and low power modes. For example, a multimode power amplifier operates in a high power mode when the base station is far from the wireless communication device, and a multimode power amplifier operates in a low power mode when the base station is close to the wireless communication device. In known multi-mode power amplifiers, switching between high and low power modes is performed by RF switches.

However, power amplifiers for wireless communication devices using switches increase the overall cost of the device. In addition, since the RF switch has negative gain, it reduces the overall efficiency of the power amplifier. Thus, there is a demand for power amplifiers that do not require an RF switch.

However, known multi-mode power amplifiers that do not include an RF switch have some problems. For example of certain known multi-mode power amplifiers, when operating in a high power mode, the RF signal is delivered to two amplification sections. The two signals amplified by each amplifier have different phases. Thereby, if two signals overlap at the output, power loss occurs due to the phase difference between them, which leads to a decrease in the efficiency of the multi-mode power amplifier. In addition, when the known multi-mode power amplifier operates in the low power mode, a small output current must flow through the output terminal of the second amplification unit in order to reduce the power consumption of the multi-mode power amplifier. In order to reduce the output current, an inductor with a fairly large value of inductance (eg, about 2-4 nH) is used as an impedance matching network at the output of the second amplifier. However, for large values of inductance, the size of the inductor (and therefore the power amplifier using such an inductor) must be quite large. As a result, provision of a reduced size wireless communication device should be considered along with its efficiency.

According to an exemplary embodiment, a multi-mode power amplifier that is operable in a high power mode and a low power mode is disclosed.

The multi-mode power amplifier is connected to a first amplifying unit, a second amplifying unit, a first impedance matching network connected to an output terminal of the first amplifying unit, an output terminal of the second amplifying unit and the first impedance matching network. A second impedance matching network and a third impedance matching network connected to output terminals of said first and second amplifying units. The third impedance matching network reduces the phase difference between the signals amplified by the first and second amplifying units in a first mode.

1 illustrates a block diagram of a high efficiency multi mode power amplifier in accordance with a representative embodiment of the present invention.
2A-2C show schematic circuit diagrams of a portion of the multi-mode power amplifier shown in FIG.
3 shows a block diagram of a high efficiency multi-mode power amplifier capable of operating in three or more power modes.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

1 illustrates a block diagram of a high efficiency multi mode power amplifier according to an exemplary embodiment.

The power amplifier 100 includes an input impedance matching network 110, a first amplifying unit 119, a second amplifying unit 124, an impedance matching network B-1 130, an impedance matching network B-2 135, Impedance matching network C 180, output impedance matching network 140 and control means 170.

 The multi-mode power amplifier 100 receives an RF signal from the driver 101, amplifies the received RF signal in a high or low power mode determined according to a desired output power level, and outputs an amplified RF signal.

The input impedance matching network 110 connected to the input terminal of the power amplifier 100 receives the RF signal through the input terminal of the power amplifier 100 and transmits it to both the first and second amplifying units 119 and 124. .

Each of the first and second amplification units 119, 124, when activated, receives and amplifies an RF signal through the input impedance matching network 110. Specifically, the first amplifying unit 119 includes an impedance matching network A-1 12 for receiving an RF signal and a first amplifier 150 for amplifying the received RF signal. The second amplifying unit 124 includes an impedance matching network A-2 125 for receiving an RF signal and a second amplifier 155 for amplifying the received RF signal.

The impedance matching network B-1 130 connected to the output terminal of the first amplifier 150 transmits the RF signal amplified by the first amplifier 150 to the output impedance matching network 140.

The impedance matching network B-2 135 connected to the output terminal of the second amplifier 155 transfers the RF signal amplified by the second amplifier 155 to the output impedance matching network 140.

Unlike the conventional multi-mode power amplifier, the multi-mode power amplifier 100 of the present embodiment includes an impedance matching network C 180 connected between the output terminals of the first and second amplifiers 150 and 155. The impedance matching network C 180 reduces the phase difference between the two signals amplified by the first and second amplifiers 150 and 155 when both the first and second amplifiers 150 and 155 are activated.

The output impedance matching network 140 transmits two signals amplified by each of the amplifiers 150 and 155 to a load, for example, an antenna connected to an output terminal.

The control means 170 is connected to the bias parts of the first amplifier 150 and the second amplifier 155, and according to the power mode of the power amplifier 100, the first amplifier 150 and the second amplifier 155 may be activated or deactivated. The operation of the power amplifier 100 is described below.

When an output power higher than a predetermined reference value is required, the power amplifier 100 operates in the high power mode. In the high power mode, the control means 170 activates the first and second amplifiers 150, 155. In addition, in the high power mode of the power amplifier, impedance matching network C 180 includes a capacitor that reduces the phase difference between the two signals amplified by each of the first and second amplifiers 150, 155. Advantageously, reducing the phase difference between the two amplified signals reduces the power loss occurring in the output impedance matching network 140. As a result, the efficiency of the power amplifier 100 can be enhanced.

When output power lower than a predetermined reference value is required, the power amplifier operates in a low power mode. In the low power mode, the control means 170 deactivates the first amplifier 150 and activates the second amplifier 155.

Moreover, power amplifier 100 may operate in an inactive mode. In the inactive mode, the control means 170 deactivates both the first and second amplifiers 150 and 155.

The first and second amplifiers 150, 155, impedance matching networks B-1 130, B-2 135, and C 180 will be described below with reference to FIGS. 2A-2C.

FIG. 2A is a schematic diagram of the first and second amplifiers 150 and 155, the impedance matching network B-1 130, the impedance matching network B-2 135 and the impedance matching network C 180 shown in FIG. 1. The circuit diagram is shown.

Each of the first amplifier 150 and the second amplifier 155 may include a plurality of transistors, and a parallel capacitor may be connected to each output terminal. In order to ensure that the power amplifier in the high power mode has a greater maximum output power (eg, at least 10 dB or more) than the output power in the low power mode, the first amplifying unit 150 may be configured by the second amplifying unit 155. ) May include more transistors (eg, 10 times or more). That is, the maximum output power of the first amplifier 150 may be greater than the second amplifier 155 (eg, at least 10 times greater).

On the other hand, as shown in FIG. 2A, the impedance matching network B-1 130 and the impedance matching network B-2 135 are bonded wires used inside the IC to which the multi-mode power amplifier 100 is provided. Bond-wire). The inductance of the bonding wire may be 0.2 nH to 0.4 nH. Impedance matching networks B-1 130, B-2 135, and C 180 constitute an impedance circuit 200.

When the multi-mode power amplifier 100 operates in the low power mode, the first amplifier 150 provides a fairly large impedance, so the first amplifier 150 is necessarily an open circuit. Accordingly, the output impedance of the second amplifier 155 is the same as the combination of the parallel capacitor 256 and the impedance circuit 200 connected to the output terminal of the second amplifier 155. The capacitance C of the capacitor of the impedance matching network C 180 is a capacitor having a capacitance C ′ in which the combination of the bonding wire of the impedance matching network B-1 130 and the impedance matching network C 180 is considerably large. 181). Note that if an appropriate value of capacitance C is used as impedance matching network C 180, the inductance L of the bonding wire is relatively very small and the capacitance C of the capacitor of impedance matching network C 180. Since the absolute value of the reactance becomes smaller, the coupling circuit of the impedance matching network C 180 and the impedance matching network B-1 130 can be seen as a capacitor 181 having a fairly large capacitance C '. . Thus, the impedance circuit 200 between node A and node B has a parallel LC resonance with bonding wires of capacitor 181 and impedance matching network B-2 135, as shown in FIG. 2B. It can be seen as a rough equivalent circuit.

When the frequency of the RF signal is w, the inductance of the bonding wire of the impedance matching network B-2 135 is L, and the capacitor 181 has the capacitance C ', the impedance Z of the parallel LC resonant circuit shown in FIG. 2B is It can be expressed as Equation 1.

[Equation 1]

At this time, if the capacitance C 'of the capacitor 181 satisfies Equation 2 below, the LC resonant circuit shown in FIG. 2B has an inductance L larger than the bonding wire of the impedance matching network B-2 135. It becomes an equivalent circuit with the inductor circuit shown in Fig. 2C having ').

[Equation 2]

에 가까워짐에 따라, 노드(A)와 노드 (B) 사이의 임피던스 회로(200)의 임피던스(Z)는 커지게 된다.Of course the capacitance (C ')

As it approaches, the impedance Z of the impedance circuit 200 between node A and node B becomes larger.

In general, bonding wires have inductances from 0.2nH to 0.4nH, which is inadequate for flowing small output currents. Therefore, in order to further reduce the output current of the power amplifier, it is necessary to use an additional inductor having a larger inductance than the bonding wire at the output terminal of the amplifier.

However, by providing an impedance matching network C 180 between the output terminals of the first and second amplifiers 150 and 155, an inductance significantly larger (eg, 10 times or more) than the inductance of the bonding wire is connected. The effect can be obtained. Thus, there is no need to connect large inductors that are large in size and relatively expensive.

3 illustrates a block diagram of a high efficiency multi-mode power amplifier capable of operating in three or more power modes according to another embodiment.

As shown in FIG. 3, by increasing the number of amplifiers to N + 1, the multi-mode power amplifier can operate in N + 1 power modes. This amplifier is identical to the amplifier 100 of FIG. 1 except for the following two points.

First, as the number of amplifiers of the power amplifier is expanded to N + 1, N + 1 impedance matching networks Ak (k = 1 to N + 1) are connected to the input terminals of each amplifier, and the output terminals of each amplifier are connected. N + 1 impedance matching networks Bk (k = 1 to N + 1) are connected to the

Secondly, N impedance matching networks C-i (i = 1 to N) are used. Specifically, the i-th impedance matching network C-i (i = 1 to N) is connected between the output terminal of the i-th amplifier and the output terminal of the (i + 1) -th amplifier. The multi-mode power amplifier is activated from the first to the i-th amplifier, and the rest can be operated in the inactivated i-th mode. The impedance matching network C-i (i = 1 to N, 380) may be formed of a capacitor having an appropriate value for optimizing the output impedance of each amplifier.

It goes without saying that the high efficiency multi-mode power amplifier described above can be integrated into integrated circuits used in wireless communication devices.

Although the embodiments have been described for the understanding of the present invention as described above, it will be understood by those skilled in the art, the present invention is not limited to the specific embodiments described herein, but variously without departing from the scope of the present invention. May be modified, changed and replaced. Therefore, it is intended that the present invention cover all modifications and variations that fall within the true spirit and scope of the present invention.

Claims (11)

A multi-mode power amplifier operable in a first mode and a second mode,
A first amplifying unit,
A second amplification unit,
A first impedance matching network connected to the output terminal of the first amplifying unit,
A second impedance matching network connected to the output terminal of the second amplifying unit and the first impedance matching network;
A third impedance matching network connected to an output terminal of the first amplifying unit and an output terminal of the second amplifying unit,
And the third impedance matching network reduces the phase difference between the signal amplified by the first amplifying unit and the signal amplified by the second amplifying unit.
The method of claim 1,
And said third impedance matching network comprises a capacitor.

The method of claim 2,
When the power amplifier is operating in the second mode, an impedance between the output terminal of the second amplifying unit and a node to which the first impedance matching network and the second impedance matching network are connected is equal to that of the second impedance matching network. Wherein the capacitance value of the capacitor is determined to be greater than impedance.
The method of claim 1,
And the first impedance matching network and the second impedance matching network each comprise a bonding wire.
The method of claim 4, wherein
The inductance of the bonding wire has a value between 0.2 nH ~ 0.4 nH.
The method of claim 1,
Control means for activating or deactivating the first and second amplifying units, respectively, according to the power mode of the power amplifier.
The method of claim 1,
And the maximum output power of the first amplifying unit is greater than the maximum output power of the second amplifying unit.
The method of claim 7, wherein
And the maximum output power of the first amplifying unit is at least ten times greater than the maximum output power of the second amplifying unit.
The method of claim 1,
The first amplification unit, when deactivated, provides a greater impedance than when activated.
An integrated circuit comprising the power amplifier of claim 1.
A wireless communication device comprising the power amplifier of claim 1.

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