KR20020038373A - A power amplifier for wireless terminal - Google Patents

Abstract

PURPOSE: A power amplification apparatus for a mobile telecommunication terminal is provided, which prevents a backward flow of a base current generated while a power is turned off to control the base current of a power amplifier by forming a backward flow preventing part. CONSTITUTION: A power supply part(11) supplies a DC power voltage(Vc2), and a power amplification part(12) amplifies and matches a signal supplied through an input port according to the power applying of the power supply part and then outputs it to the external. A bias part(13) operates to maintain a bias of the power amplification part and also generates a bias current. And a backward flow preventing part(14) prevents a backward flow of a current generated according to an on/off operation of the power supplied to control the base current being output from the bias part.

Description

Power amplifier for mobile communication terminal {A power amplifier for wireless terminal}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power amplifier for a mobile communication terminal, and more particularly, to a power amplifier for a mobile communication terminal which prevents backflow of a base current generated when power is turned off to adjust a base current of a power amplifier.

With the expansion of the communication market, the demand for mobile communication terminals and communication devices has reached a considerable amount, and there is a need for excellent performance and small size and light weight communication devices. Accordingly, technical efforts to improve performance within a limited area of a communication device continue.

1 is a circuit diagram illustrating a conventional power amplifier for a mobile communication terminal. Referring to this, a power supply unit 1 for supplying a DC power supply Vc1 supplied from the outside and a power supply Vc1 to the power supply unit 1 are shown. ) Is applied to the power amplifier (2) and amplified and matched RF (RF) signal supplied through the input terminal (I1) and output (O1) to the outside, and the bias of the power amplifier (2) It is composed of a bias unit (3) for operating at the same time to generate a base current.

The bias unit 3 is a transistor Q12 for maintaining a turn-on voltage to supply a bias of the power amplifier Q11, and a base current of the transistor Q12 connected to a base of the transistor Q12. It is composed of a bias fixing end (Vg1) for supplying.

Referring to the operation of the conventional power amplifier for mobile communication terminal configured as described above are as follows.

DC power supply (Vc1) is applied to the collector current of the power amplifier (Q11) through the inductor (L1) to prevent the alternating current (C1) DC current through the power supply (1) to pass through the alternating current, the power amplifier The base current is applied to the power amplifier Q11 by the base current power supply Vt1 connected to the base of Q11.

When the base current power source Vt1 is on, the transistor Q12 of the bias unit 3 operates as an amplifier to supply a base current to the power amplifier Q11.

When the base current power supply Vt1 is turned off, the transistor Q12 is grounded so that the base current is not supplied to the power amplifier Q11 and flows backward.

The conventional power amplifier for a mobile communication terminal has a problem in that the base current is not supplied to the power amplifier and flows backward because the transistor is grounded when the power supply for adjusting the base current of the power amplifier is grounded.

The present invention has been made to solve the above problems of the prior art, the object of which is to prevent the back current of the base current generated when the power off for adjusting the base current of the power amplifier by forming a backflow prevention portion consisting of a plurality of transistors The present invention provides a power amplifier for a mobile communication terminal.

1 is a circuit diagram showing a power amplifier for a mobile communication terminal according to the prior art;

2 is a circuit diagram showing a power amplifier for a mobile communication terminal according to the present invention;

<Explanation of symbols on main parts of the drawings>

11 power supply unit 12 power amplification unit

13: bias portion 14: backflow prevention portion

According to a first aspect of the present invention for solving the above problems, a power supply unit for supplying DC power and a signal supplied through an input terminal according to the power supply of the power supply unit are amplified and A power amplifier that is matched and output to the outside, a bias unit that operates to maintain the bias of the power amplifier and simultaneously generates and outputs a bias current, and turns on / off the power supplied to control the base current output from the bias unit; It is composed of a backflow prevention unit for preventing the backflow of the current generated by the off operation.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

With the expansion of the communication market, the demand for mobile communication terminals and communication devices has reached a considerable amount, and efforts to develop excellent and small sized communication devices have continued.

Among them, the usage time of the battery, which occupies a large portion of the terminal or communication device, is sensitive to the efficiency of the power amplifier.

However, in the actual use of the terminal, the use of low power of about 0㏈m to 10㏈m is more important than the frequency of use at the maximum output, so it is important to improve the efficiency at low power to extend the battery usage time.

As a method of improving the efficiency of the power amplifier, there is a method of reducing the voltage and a method of reducing the current. FIG. 2 is a circuit diagram illustrating a power amplifier for a mobile communication terminal according to the present invention to which the method of reducing current is applied.

Power amplification device for a mobile communication terminal according to the present invention amplifies and matches the power input unit 11 for supplying a DC power supply (Vc2) and the signal input to the system when the power supply (Vc2) is applied to the power supply (11) And a power amplifier 12 output to the outside, and a bias unit 13 that operates as a bias of the power amplifier 12 and generates and outputs a base current.

The bias part 13 includes a backflow prevention part 14 that prevents backflow of the base current generated by turning on / off the power supply Vt2 to control the base current supplied to the power amplifier 12. .

The power supply unit 11 is connected to the bypass capacitor (C2) for passing only alternating current between the power supply (Vc1) and the ground terminal is supplied, and in parallel with the bypass capacitor (C2) to control the high-frequency current of a specific frequency It consists of frequency choke (L2) which prevents the passage of AC current.

The power amplifier 12 has an input terminal I2 for inputting an RF signal to the system and an excitation and amplification of the signal input through the input terminal I2 according to a current applied from the power supply unit 11. An output terminal for outputting the amplifier Q21, an output matching unit M2 for matching the signal output from the amplifier Q21 to be the maximum output, and a signal output from the output matching unit M2 to the outside It consists of (O2).

The bias unit 13 is connected to the base of the amplifier Q21 of the power amplifier 12 to maintain a bias voltage and generate and output a bias current. When the power supply Vc1 is applied from the voltage supply unit 11, the amplifier The transistor Q22 maintains a turn-on voltage at the base-emitter, and a power supply terminal Vg2 connected to the base of the transistor Q22 to supply a base current of the transistor.

The backflow prevention unit 14 connects a plurality of transistors Q23, Q24, and Q25 in series to operate as a base-collector diode to provide a collector of the transistor Q22 according to on / off of the base current regulating power supply Vt2. The applied voltage is varied to prevent backflow of the base current.

Looking at the operation of the power amplifier for mobile communication terminal of the present invention configured as described above are as follows.

When the base current regulating power supply Vt2 of 3V is applied and the base current regulating power supply Vt2 is turned on, the second transistor Q23 is operated as a base-collector diode, so that its driving voltage of about 1.1V is decreased. The collector of the first transistor Q22 is powered by about 1.9V.

A power supply of about 2.6 V is applied to the power supply terminal Vg2 so that the first transistor Q22 operates as an amplifier, so that the first transistor Q22 amplifies the base current and supplies it to the base current of the amplifier Q21. do.

However, when the base current regulating power supply Vt2 is turned off to 0 V, the second transistor Q23 is turned off, and about 2.2 V, which is the sum of the driving voltages of the third and fourth transistors Q24 and Q25, is equal to the first transistor Q22. ), The driving voltage of the first transistor Q22 is also applied, and a voltage of about 3.3V is applied, so that the base-collector of the first transistor Q22 is not driven, so that the first transistor Q22 Is supplied in the form of a base-emitter diode to supply a base current to the amplifier Q21.

In this way, even when the base current regulating power is turned off, the base current can be prevented from being reversed by the reverse voltage applied to the backflow prevention part.

The power amplifier for a mobile communication terminal of the present invention configured as described above has an effect of preventing the back current of the base current generated when the power is turned off to adjust the base current of the power amplifier by forming a backflow prevention part including a plurality of transistors. There is.

In addition, the power amplifier for the mobile communication terminal of the present invention has the effect of reducing the current consumption of the bias circuit by preventing the first transistor from being driven by the base-collector diode.

Claims (2)

A power supply unit for supplying a DC power supply, a power amplification unit that is amplified and matched through the input terminal according to the power supply of the power supply unit is output to the outside, and the bias current of the power amplification unit is maintained to maintain a bias current A mobile communication terminal comprising: a bias unit for generating and outputting a; and a backflow prevention unit for preventing a reverse flow of current generated according to an on / off operation of a power supply supplied to control a base current output from the bias unit. Power amplifier. The method of claim 1, The reverse current prevention unit is a plurality of transistors are connected in series is a power amplifier for a mobile communication terminal, characterized in that the reverse voltage is applied when the power for the bias current control is turned off.