KR20030087089A - Bias circuit of mmic die chip for power amplifier module - Google Patents

Abstract

PURPOSE: A bias circuit of an MMIC die chip for RF power amplifier is provided to supply the constant current to the inside of the MMIC die chip and reduce a variation of characteristic due to a variation of temperature by forming the bias circuit of the MMIC die chip with a differential amplifier circuit. CONSTITUTION: A bias circuit of an MMIC die chip for RF power amplifier includes a driver amplifier, an interstage match, and a power amplifier. The bias circuit is formed with a differential amplifier circuit. The differential amplifier circuit is formed with two transistors of the same characteristic having emitters connected to each other. The constant current is obtained and the variation of characteristic due to the variation of temperature is reduced by the differential amplifier circuit including two transistors of the same characteristic.

Description

Bias circuit of MMC die chip for high frequency power amplifier {BIAS CIRCUIT OF MMIC DIE CHIP FOR POWER AMPLIFIER MODULE}

The present invention relates to a high frequency power amplifier. Specifically, a bias circuit of a MMIC die chip used in a high frequency power amplifier is implemented by using a differential amplifier circuit. It relates to a bias circuit in an MMIC die chip for a high frequency power amplifier that supplies a constant current and is less affected by temperature changes.

As the demand for portable communication is rapidly increasing, it is an important problem that power of wireless signals transmitted / received must be used efficiently by using a battery of a mobile communication terminal.

The mobile communication terminal is composed of a receiver for receiving the contents of the other party and a transmitter for transmitting its own information. That is, it has a function of converting a high frequency signal into a baseband signal and vice versa. In the dual transmitter, a high frequency power amplifier is required to deliver an output beyond reception sensitivity to the other party.

Looking at the configuration of such a high-frequency power amplifier, as shown in Figure 1, the mobile station modem 10, the radio frequency transmitter 20, the bias circuit 30, the input match 40, the driver amplifier 50 ), An interstage match 60, a power amplifier 70, and an output match 80.

The mobile station modem (MSM) 10 detects the strength of the signal received from the base station and outputs a control signal corresponding thereto, and converts the power mode according to the strength of the signal to signal through the R0 and R1 terminals. Outputs

A radio frequency transmitter (RFT) 20 outputs an RF signal whose RF signal level is varied by a control signal output to the mobile station modem 10.

The bias circuit 30 changes the bias point by adjusting a base current of the driver amplifier 50 and the power amplifier 70 during the low power mode operation of the high frequency power amplifier.

In the input match 40, a circuit by R, L, and C is implemented so that maximum power can be transmitted to the driver amplifier 50 when an RF signal is input from the radio frequency transmitter 20.

The driver amplifier 50 operates the RF signal according to the base current output from the bias circuit 30 to first amplify and transfer the amplified RF signal to the interstage match 60.

The interstage match 60 is implemented by circuits R, L, and C so that the output of the driver amplifier 50 can deliver the maximum power to the power amplifier 70.

The power amplifier 70 is operated according to the base current output from the bias circuit 30 to secondly amplify the RF signal applied through the interstage match 60 to the output match 80, where the driver amplifier 50, the interstage match 60, and the power amplifier 70 are integrated into one MMIC die chip 90. As shown in FIG. Here, the MMIC die chip 90 also uses a bias circuit for applying a constant current to drive it, which is a bias circuit of a general current mirror type as shown in FIG. Is connected to the base (gate) or collector (drain) of the driver amplifier 50 or the power amplifier 70.

Output Match 70 implements circuits by R, L, and C in consideration of maximum output and other characteristics.

Looking at the operation according to the power mode of the high-frequency power amplifier, the driver amplifier 50 and the power amplifier 70 by controlling the P0, P1 terminals of the high-frequency power amplifier by the output signal of the R0, R1 terminal in the mobile station modem 10 The bias point of the internal transistor is changed, and it operates by lowering the Idle current in the low power mode. That is, the operating voltage Vcc is 2.2V to 4.2V (supply voltage of the terminal battery), and the reference voltage applied from the battery is 3.0V. During the low power mode operation, the base current of the driver amplifier 50 and the power amplifier 70 is adjusted (bias circuit) to change the bias point, that is, operate by lowering the idle current (usually in high power mode and two low power modes). Classified). At this time, the bias point is operated by varying the reference voltage (Vref) 3.0V in the bias circuit (30).

On the other hand, referring to the operation of the bias circuit of the MMIC die chip, first, since the characteristics (amplitude, etc.) of the first transistor Q1 and the second transistor Q2 are configured to be the same (β1 = β2), the first transistor ( The currents flowing through the terminals of Q1) and the second transistor Q2 are the same.

As a result, since the current flowing through the second transistor Q2 is determined by the first transistor Q1, a constant constant current always flows through the second transistor Q2.

However, since the bias circuit of the conventional MMIC die chip is affected by temperature change, there is a problem in that it does not stably generate a constant constant current due to malfunction or breakage caused by temperature.

Accordingly, an object of the present invention is to solve the above problems, and to provide a constant current while being less affected by temperature changes.

1 is a block diagram schematically illustrating a high frequency power amplifier used in a conventional mobile communication terminal.

2 is a circuit diagram showing the configuration and operation of a bias circuit of a conventional MMIC die chip for a high frequency power amplifier.

Figure 3 is a circuit diagram showing the configuration and operation of the bias circuit of the MMIC die chip for a high frequency power amplifier according to the present invention

<Description of the symbols for the main parts of the drawings>

100: bias circuit of MMIC die chip

R10, R20: resistors Q10, Q20: 10th and 20th transistors

Features of the present invention for achieving the above object,

In a bias circuit of an MMIC die chip of a high frequency power amplifier composed of a driver amplifier, an interstage match, and a power amplifier,

The bias circuit,

An emitter of two identical transistors is configured as an emitter coupled differential amplifier circuit coupled to each other.

Hereinafter, the configuration of the bias circuit of the MMIC die chip for a high frequency power amplifier according to the present invention will be described in detail with reference to FIG.

3 is a circuit diagram showing the configuration and operation of a bias circuit of the MMIC die chip for a high frequency power amplifier according to the present invention.

Referring to FIG. 3, in the bias circuit 100 of the MMIC die chip for a high frequency power amplifier according to the present invention, a resistor of a collector of a tenth transistor Q10 and a twentieth transistor Q20 having the same two characteristics is the same. Emitter-coupled differential amplifiers commonly connected to the constant voltage terminal (Vcc) through the resistors (R10, R20) having a value, the same DC voltage (V1, V2) is applied to each base, the emitter is commonly connected Circuit (hereinafter, referred to as differential amplifier circuit). That is, R10 = R20, V1 = V2, and Q10 = Q20.

On the other hand, the emitter, which is the output terminal of the differential amplifier circuit, is connected to the base (gate) or collector (drain) of the driver amplifier 50 or the power amplifier 70 of the MMIC die chip.

Referring to the operation of the bias circuit of the MMIC die chip for the high frequency power amplifier, I _E1 = I _E2 when V1 = V2 according to Kirchhoff's current law, and I _E1 + I _E2 = I ₀ is induced. As a result, a constant value of output current I ₀ can be obtained at all times.

In addition, the transistor, which is a semiconductor, changes its output current very severely due to temperature change. When a differential amplifier circuit is used, current change can be prevented due to temperature drift. For example, it can be seen that the slope of the characteristic curve shifts to the left at a rate of about 2 mV with respect to the temperature rise of 1 ° C. in the V _BE -I _E characteristic curve of the transistor. That is, no matter how constant V _BE is, if the temperature rises, the transistor I _E will rise.

On the other hand, in the differential amplifier circuit, the output current I ₀ remains constant as the sum of I _E1 and I _E2 , so that I _E1 and I _E2 do not change due to temperature change.

Therefore, when the differential amplifier circuit is used as the bias circuit, it is possible to obtain the same output, that is, the constant current, and to prevent the characteristic change from occurring in the temperature change.

As described above, according to the bias circuit of the MMIC die chip for a high frequency power amplifier according to the present invention, by implementing a bias circuit of the MMIC die chip used in the high frequency power amplifier by using a differential amplifier circuit, a constant constant current inside the die chip is achieved. While supplying, it can be less affected by temperature changes.

Claims (1)

In a bias circuit of an MMIC die chip of a high frequency power amplifier composed of a driver amplifier, an interstage match, and a power amplifier, The bias circuit, A bias circuit of an MMIC die chip for a high frequency power amplifier, characterized in that the emitter of two identical transistors is composed of an emitter coupled differential amplifier circuit coupled to each other.