WO2017156707A1

WO2017156707A1 - Protection device and method for power amplifier

Info

Publication number: WO2017156707A1
Application number: PCT/CN2016/076366
Authority: WO
Inventors: 陈士国
Original assignee: 华为技术有限公司
Priority date: 2016-03-15
Filing date: 2016-03-15
Publication date: 2017-09-21
Also published as: CN107534418A

Abstract

A protection device and method for a power amplifier (20), the protection device of the power amplifier (20) comprising: a current detection unit (23), for detecting an input current of the power-supply terminal of the power amplifier (20); a terminal processing unit (24) being used, when the input current of the power-supply terminal detected by the current detection unit (23) is greater than a first threshold value, for adjusting the input current of the power-supply terminal, and/or adjusting the power of an input signal of the power amplifier (20), and/or adjusting a gain of the power amplifier (20). The invention can effectively protect against an overcurrent that breaks down the power amplifier (20), and fully protect the power amplifier (20).

Description

Power amplifier protection device and method

Technical field

The present invention relates to the field of intelligent terminal technologies, and in particular, to a protection device and method for a power amplifier.

Background technique

Many devices have a certain rated current. If the operating current exceeds the rated current, the device is at risk of damage. In general, the most powerful amplifier in the power amplifier PA (Power Amplifier) consists of the most basic bipolar transistor or FET. Among them, whether it is a bipolar transistor or a field effect transistor, there is a breakdown region, such as the N-channel depletion field effect transistor output characteristic curve shown in FIG. 1, when in the breakdown region, the amplifier The current is extremely fast, and the amplifier's PN junction or MOS transistor is easily broken down.

In a power amplifier protection method of the prior art, the PA is protected by stabilizing the input voltage of the PA, and to some extent, the PA damage caused by the overvoltage is limited, and at the same time, there is a certain influence on the surge and the like. Preventive effect. However, the prior art only protects at the voltage level. In fact, the rated voltage limits the static operating point of the PA, and the limited voltage limits the application of the PA. In addition, due to the influence of PA individual differences, a small number of PAs in the vicinity of the saturation voltage, the current can also increase rapidly, which is not solved by the regulator protection.

In another protection method of the power amplifier of the prior art, the electrostatic discharge ESD (Electro-Static discharge) is used to protect the PA, which can protect against the influence of lightning and static electricity and protect the PA to a certain extent. However, ESD protection only works when the voltage is much higher than the rated voltage, usually KV level, and PA does not need such high voltage when it breaks down. Over-current under normal voltage can also penetrate PA, so voltage regulation and ESD protection The PA cannot be fully protected.

Summary of the invention

Embodiments of the present invention provide a protection device and method for a power amplifier, which can comprehensively protect a power amplifier.

In one aspect, a protection device for a power amplifier is provided, comprising: a current detecting unit for detecting an input current of a power amplifier power supply terminal; and a terminal processing unit, when the input current of the power supply terminal detected by the current detecting unit is greater than a first threshold, Adjusting the input current at the power supply terminal, and/or adjusting the power of the input signal of the power amplifier, and/or adjusting the gain of the power amplifier.

Preferably, the apparatus further includes a power supply circuit for providing an operating voltage to the power amplifier; wherein the power supply circuit includes a first control unit, and the first control unit receives the first output of the terminal processing unit when the input current is greater than the first threshold The control signal limits the current output from the power supply circuit to the power supply terminal of the power amplifier.

Preferably, the apparatus further includes a PA radio frequency input integrated circuit coupled to the radio frequency input end of the power amplifier for providing an input power signal to the power amplifier; wherein the PA radio frequency input integrated circuit includes a second control unit at the input When the current is greater than the first threshold, the second control unit receives the second control signal output by the terminal processing unit, and controls the PA radio frequency input integrated circuit to reduce the output power.

Preferably, the power amplifier includes a third control unit, and the third control unit is configured to adjust the PA gain position; the terminal processing unit is further configured to output the third control signal to the third control unit when the input current is greater than the first threshold, The third control signal is used to control the third control unit to lower the gain gear of the power amplifier.

It should be noted that the current limiting protection scheme of the power amplifier according to the embodiment of the present invention includes: adjusting the input current of the power supply end of the power amplifier, the power and/or gain of the input signal, and the like. In practical applications, the current limiting protection scheme of one or more of the combined power amplifiers can be selected according to the design requirements to more fully protect the power amplifier from excessive breakdown and operating current.

Preferably, the current detecting unit comprises: a parallel resistance device and a current detecting device, wherein the resistance device is connected in series to the power supply end of the power amplifier, and the current detecting device obtains the input current of the power supply terminal according to the voltage across the resistance device.

Preferably, the resistive device is a varistor.

It should be noted that the varistor is more sensitive to voltage changes, and the detected current accuracy is higher than that of the general resistance. At the same time, a varistor with a small resistance can be selected without introducing too much power.

In another aspect, a method for protecting a power amplifier is provided, comprising: detecting an input current of a power amplifier power supply terminal; adjusting an input current of the power supply terminal when the input current is greater than the first threshold, and/or adjusting a power of the input signal of the power amplifier , and / or adjust the gain of the power amplifier.

Preferably, when the input current is greater than the first threshold, adjusting the input current of the power supply terminal specifically includes: limiting the current output by the power supply circuit to the power supply end of the power amplifier when the input current is greater than the first threshold; and the power supply circuit provides the operating voltage for the power amplifier.

Preferably, when the input current is greater than the first threshold, adjusting the input power of the power amplifier's input signal specifically includes: reducing the power of the input signal of the power amplifier when the input current is greater than the first threshold.

Preferably, when the input current is greater than the first threshold, adjusting the gain of the power amplifier comprises: adjusting the gain position of the power amplifier in combination with the adjustable gain range of the power amplifier when the input current is greater than the first threshold.

Preferably, detecting the input current of the power amplifier power supply end comprises: obtaining an input current of the power supply end according to a voltage across the resistance device connected in series with the power supply unit and the power amplifier power supply end.

Embodiments of the present invention provide a protection apparatus and method for a power amplifier, wherein an input current of a power supply terminal is detected; when an input current is greater than a first threshold, an input current of the power supply terminal is adjusted, and/or a power of an input signal of the power amplifier is adjusted. , and / or adjust the gain of the power amplifier. It can be seen that, in the embodiment of the present invention, the input current of the PA power supply end is collected, and it is determined whether it is greater than a certain threshold. If it is greater than, the current limiting measure is enabled to further protect the PA. The PA protection device and method provided by the embodiments of the present invention can effectively prevent the overcurrent breakdown PA and comprehensively protect the PA.

DRAWINGS

1 is a schematic diagram showing an output characteristic curve of an N-channel depletion field effect transistor;

2 is a structural diagram of a PA protection device according to an embodiment of the present invention;

FIG. 3 is a flowchart of a PA protection method according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

In order to facilitate the understanding of the embodiments of the present invention, the embodiments of the present invention are not to be construed as limiting.

The terminal power amplifier PA mainly includes the following ports:

Vcc: supply voltage to the amplifier circuit inside the PA;

Control Unit (control unit 3): is connected to the control unit 3 for adjusting the gain inside the PA, and is a gain adjustment port of the PA, and controls the gain position of the PA;

Vbat: supply voltage to the control unit 3 inside the PA;

RFin: is the PA RF signal input port;

RFout: is the PA RF signal output port;

CPL (Coupling Circuit): is a PA coupling end for detecting PA output power;

It should be noted that the detection method of the PA output power is specifically as follows: from the PA RF signal output port RFout coupling part PA output power to the CPL end, the coupled partial PA output power is fed back to the terminal processing unit through the external power detecting unit, and the terminal is made The processing unit acquires the output power of the PA.

The input current of the Vcc power supply terminal accounts for most of the PA operating current. Vcc directly supplies power to the internal amplification tube of the PA. The input current of the Vcc power supply terminal can be used as a standard for judging the PA operating current. In order to solve In the prior art, the voltage regulation and the ESD protection cannot fully protect the PA. The embodiment of the present invention collects the input current of the Vcc power supply terminal and determines whether it is greater than a certain threshold. If the current of the PA power supply terminal is greater than a certain threshold, the corresponding limit is enabled. Flow measures to fully protect the PA.

The following is an example of FIG. 2, which is a structural diagram of a PA protection device according to an embodiment of the present invention, where the device includes:

The power supply circuit 21 is configured to provide an operating voltage for the internal circuit of the PA to ensure normal operation of the PA devices, such as an amplifier and the like. The power supply circuit includes a control unit 1 for controlling the current input by the power supply circuit to the PA power supply terminal.

The PA RF input integrated circuit RFIC 22 is used to provide input power to the PA, and the output of the PA RF input integrated circuit 22 is connected to the PA RF signal input terminal RFin. The PA radio frequency input integrated circuit includes a control unit 2 for controlling the output power of the PA radio frequency input integrated circuit 22.

The current detecting unit 23 is configured to collect an input current of the PA power supply end. The method includes: a current detecting device 230 and a resistance device 231 connected in parallel. The resistor device 231 is connected in series between the power supply circuit 21 and the PA power supply terminal Vcc. The current detecting device 230 is configured to collect the voltage across the resistance device 231, thereby obtaining the current of the PA power supply terminal. When the input current of the PA power supply terminal is greater than the first threshold, the information is sent to the terminal processing unit 24 to take corresponding current limiting measures to protect the PA. In order to avoid the breakdown of its working current is too large.

It should be noted that in order to reduce the influence on the power supply circuit 21, the resistance device 231 needs to have high precision and low power consumption. It is recommended that the resistance device 231 can employ a varistor having a small resistance value, such as a milliohm (mΩ) level. Since the varistor is more sensitive to voltage changes, the detected current accuracy is also higher than the general resistance. At the same time, the varistor with a small resistance does not introduce too much power.

The terminal processing unit 24, when the current of the PA power supply terminal is greater than the first threshold, enables a current limiting measure to further protect the PA. When the input current of the PA power supply terminal detected by the current detecting unit 23 is greater than the first threshold, it is used to adjust the input current of the power supply terminal, and/or adjust the power of the input signal of the power amplifier, and/or adjust the gain of the power amplifier.

It should be noted that the control unit 1, the control unit 2, and the control unit 3 are respectively the first control list. Element, second control unit and third control unit.

The power detecting unit 25 is connected between the PA coupling end CPL and the terminal processing unit 24 for feeding part of the output power of the PA coupled from the PA radio frequency signal output terminal RFout to the terminal processing unit 24 for the terminal processing unit 24 to acquire. PA output power.

In the first aspect of the embodiment, when the current detecting unit 23 detects that the current of the PA power supply terminal is greater than the first threshold, it feeds back to the terminal processing unit 24, and the terminal processing unit 24 outputs the control signal Control 1 to the control unit 1 of the power supply circuit 21. Modulate the input current of the PA supply terminal. The control unit 1 receives the Control 1 signal, limits the current output from the power supply circuit 21 to the PA supply terminal, and protects the PA from being broken down.

It should be noted that, since there are many types of PAs involved in the terminal, they correspond to different uses. However, the saturation current of the terminal PA is usually in the range of 100 milliamperes or amps, and the saturation operating current parameters of different PAs may be used. , set different power supply input current threshold. Wherein, the control unit 1 can include a current limiting device.

Specifically, the first threshold may be a current value threshold preset according to the saturation operating current of the PA, and it may be understood that the first threshold may also be adjusted as needed.

In the second aspect of the embodiment, when the current detecting unit 23 detects that the current of the PA power supply terminal is greater than the first threshold, it feeds back to the terminal processing unit 24, and the terminal processing unit 24 outputs the control signal Control 2 to the PA radio frequency input integrated circuit 22. The control unit 2 controls the PA radio frequency input integrated circuit 22 to reduce its output power, that is, to reduce the power input of the PA, and protect the PA from breakdown due to excessive operating current.

It should be noted that for each PA, a relatively safe threshold current can be set for it. Once the PA operating current is greater than the threshold, the output power of the PA power input circuit can be reduced by the terminal processing unit, thereby reducing the operating current to below the threshold current; if the operating current is close to the threshold current, the PA power can also be controlled. Enter the output power of the circuit so that it no longer increases.

In the third aspect of the embodiment, when the current detecting unit 23 detects that the current of the PA power supply terminal is greater than the first threshold, it feeds back to the terminal processing unit 24, and the terminal processing unit 24 outputs a control signal. Control 3 to PA 20 Control Unit (control unit 3) to adjust the PA gain position, control unit 3 evaluates the gain adjustable range of PA according to PA performance and control mechanism, control unit 3 of control PA slightly lowers PA gain file Bit, while avoiding pushing the PA into the low gain saturation region to limit the operating current of the power amplifier and protect the PA from breakdown.

It should be noted that usually, the PA has multiple gain gears. Generally speaking, when the external conditions are the same, the higher the gain of the PA, the larger the operating current consumed. Therefore, lowering the PA gain gear reduces the operating current of the PA to a certain extent, and protects the PA from excessive breakdown due to excessive operating current. Therefore, lower the gain position of the PA, and the corresponding PA current consumption will decrease. However, this method cannot be easily implemented. First, the PA gain is greatly reduced, which affects the communication performance. Secondly, if the gain is only reduced, it is easy to push the PA into the saturation region under low gain. For the PA, there is still damage. risks of.

It should be noted that the protection device for the PA according to the embodiment of the present invention includes three aspects of current limiting measures, which can be selected according to actual design requirements, and the current limiting measures are selected in one aspect to further design the specific device. For example, in the case of conveniently limiting the current output from the power supply circuit to the PA power supply terminal, the first aspect of the embodiment may be selected, and the terminal processing unit outputs the control signal Control 1 to the control unit 1 of the power supply circuit to comprehensively protect the PA; When the output power of the PA radio input integrated circuit is convenient, the second aspect of the embodiment may be selected, and the terminal processing unit outputs the control signal Control 2 to the control unit 2 of the PA radio input integrated circuit to comprehensively protect the PA; For example, in the case where the PA gain adjustability is high, the third aspect of the embodiment can be selected, and the terminal processing unit outputs the control signals Control 3 to the control unit 3 of the PA to comprehensively protect the PA. At the same time, the three-way current limiting schemes provided in this embodiment can also be combined. By combining the PA parameters and the specific distribution of the PAs in the terminal, the combination of the specific protection schemes can be flexibly allocated.

The following is an example of FIG. 3, which is a flowchart of a PA protection method according to an embodiment of the present invention, where the method includes:

In step 300, the input current of the PA power supply terminal is detected.

A series resistor device is connected to the PA supply terminal, and the PA is obtained according to the resistance of the resistance device and the voltage across the resistor. Input current at the power supply. In order to reduce the influence on the power supply circuit, the resistance device requires high precision and low power consumption.

Specifically, it is recommended that the resistance device 231 employ a varistor having a small resistance value, such as a milliohm (mΩ) level. Since the varistor is more sensitive to voltage changes, the detected current accuracy is also higher than the general resistance. At the same time, the varistor with a small resistance does not introduce too much power.

Step 301: When the input current of the power supply terminal is greater than the first threshold, adjust the input current of the power supply terminal, and/or adjust the power of the input signal of the power amplifier, and/or adjust the gain of the power amplifier.

Specifically, when the input current of the PA power supply end is greater than the first threshold, the following current limiting measures may be adopted:

1. When the input current of the PA power supply terminal is greater than the first threshold, the control unit 1 in the power supply circuit is controlled to limit the input current of the power supply circuit to the PA power supply terminal, and the PA is protected from being broken due to excessive operating current. Wherein, the control unit 1 can include a current limiting device.

2. When the input current of the PA power supply terminal is greater than the first threshold, the control unit 2 of the PA radio input integrated circuit is adjusted to adjust the output power of the PA radio input integrated circuit to protect the PA from being broken due to excessive operating current. Among them, the PA RF input integrated circuit provides input power to the PA. The control unit 2 may take the form of software, hardware or a combination of software and hardware, or may exist in other forms.

In an example, when the input current of the PA power supply terminal is greater than or equal to the first threshold, the output power of the PA RF input integrated circuit is adjusted by the control unit 2 of the PA radio input integrated circuit, that is, the PA is adjusted by the control unit 2. Input power. For example, when the input current of the PA power supply terminal is greater than or equal to the first threshold, the PA RF input integrated circuit is controlled so that its output power is slightly reduced or remains unchanged.

3. When the input current of the PA power supply terminal is greater than the first threshold, combine the PA performance and mechanism to evaluate the PA gain adjustable range, and lower the PA gain gear position to ensure that the PA gain will not be greatly reduced and affect the communication performance, and will not Push the PA into the low gain saturation region to damage it.

It should be noted that the above three current limiting schemes can be flexibly selected according to the actual design, and one of them can be selected, and at the same time, multiple combinations can be selected to fully protect the PA from overcurrent breakdown.

The protection device and method for the PA provided by the embodiment of the invention effectively reduce the PA damage caused by the amplifier entering the breakdown region in the PA or the current is sharply increased. The technical solution of the present invention can also be applied to PA protection in the field of audio and the like, and similar protection methods can also be adopted for some important devices, thereby effectively reducing market failure.

A person skilled in the art should further appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both, in order to clearly illustrate hardware and software. Interchangeability, the composition and steps of the various examples have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods for implementing the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed by the present invention. Alternatives are intended to be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The technical solution of the present invention can also be applied to PA protection applications in the case of audio, power conversion, etc., and PA protection applications in the case of base stations, wireless communications, and the like. The PA current limiting protection method in these fields is also within the scope of protection of the present invention as long as it is the same as the present invention.

Claims

A protection device for a power amplifier, characterized in that the device comprises:

a current detecting unit for detecting an input current of a power supply end of the power amplifier;

a terminal processing unit, configured to adjust an input current of the power supply terminal, and/or adjust a power of an input signal of the power amplifier, and/or adjust a gain of the power amplifier when the input current detected by the current detecting unit is greater than a first threshold .
The device of claim 1 further comprising:

a power supply circuit for providing an operating voltage to the power amplifier;

The power supply circuit includes a first control unit, and when the input current is greater than the first threshold, the first control unit receives a first control signal output by the terminal processing unit, and limits the output of the power supply circuit. Current to the power supply terminal of the power amplifier;
The device of claim 1 further comprising:

a PA radio frequency input integrated circuit connected to the radio frequency input end of the power amplifier for providing an input signal to the power amplifier;

The PA radio frequency input integrated circuit includes a second control unit, when the input current is greater than the first threshold, the second control unit receives a second control signal output by the terminal processing unit, and controls the The PA RF input integrated circuit reduces the output power.
The apparatus according to claim 1, wherein said power amplifier comprises a third control unit for adjusting a gain position of said power amplifier;

The terminal processing unit is further configured to: when the input current is greater than the first threshold, output a third control signal to the third control unit, where the third control signal is used to control the third control unit The gain gear of the power amplifier is turned down.
The device according to any one of claims 1 to 4, wherein the current detecting unit comprises: a parallel resistance device and a current detecting device, wherein the resistance device is connected in series to the power supply end, and the current detection The device obtains an input current of the power supply terminal according to a voltage across the resistance device.
The device according to claim 5, wherein said resistance device is a varistor.
A method for protecting a power amplifier, characterized in that the method comprises:

Detecting the input current of the power amplifier power supply terminal;

When the input current is greater than the first threshold, the input current of the power supply terminal is adjusted, and/or the power of the input signal of the power amplifier is adjusted, and/or the gain of the power amplifier is adjusted.
The method according to claim 7, wherein the adjusting the input current of the power supply terminal when the input current is greater than the first threshold comprises:

Limiting a current output by the power supply circuit to the power supply end of the power amplifier when the input current is greater than the first threshold;

The power supply circuit provides an operating voltage to the power amplifier.
The method according to claim 7, wherein the adjusting the power of the input signal of the power amplifier when the input current is greater than the first threshold comprises:

The power of the input signal of the power amplifier is reduced when the input current is greater than a first threshold.
The method according to claim 7, wherein the adjusting the gain of the power amplifier when the input current is greater than the first threshold comprises:

When the input current is greater than the first threshold, in conjunction with the adjustable gain range of the power amplifier, the gain gear of the power amplifier is turned down.
The method according to any one of claims 7 to 10, wherein the detecting the input current of the power amplifier power supply terminal comprises:

An input current of the power supply terminal is obtained according to a voltage across the resistance device connected in series between the power supply circuit and the power supply terminal of the power amplifier.
The method of claim 11 wherein said resistive device is a varistor.