KR-20260063208-A - Power amplifier simultaneously implementing envelope tracking and digital pre-distortion

Abstract

The present invention relates to a power amplifier that simultaneously implements envelope tracking and digital pre-distortion, and more specifically, to a power amplifier that simultaneously implements envelope tracking and digital pre-distortion, which can simultaneously implement ET and DPD algorithms by improving the efficiency of the amplifier by changing the supply voltage of the power amplifier in a power amplifier that applies digital pre-distortion technology. According to the present invention, a digital pre-distortion algorithm of a power amplifier to which envelope tracking technology is applied can reflect changes in RF characteristics according to the VCC level, and has the effect of detecting changes in characteristics appearing in the RF output according to the envelope BW of the VCC and generating an inverse distortion signal to linearize the output signal of the power amplifier.

Inventors

• 김형수
• 이상현
• 고락규

Assignees

• 주식회사 휴미디어

Dates

Publication Date

20260507

Application Date

20241030

Claims (3)

1. As a power amplifier that simultaneously implements ET and DPD algorithms by improving amplifier efficiency through a method of changing the supply voltage by applying digital pre-distortion technology, A signal processing unit (110) that executes a digital pre-distortion algorithm and an envelope tracking algorithm; A converter (120) that converts the RF signal or baseband signal output from the signal processing unit (110) from a digital signal to an analog signal, respectively; A first LPF (131) and a second LPF (132) that pass only a portion of the signal band of the analog signal output to the converter (120); A first mixer (141) and a second mixer (142) that respectively invert the phase of a low-band signal passing through the first LPF (131) and the second LPF (132); A combiner (150) that combines signals passed through the first mixer (141) and the second mixer (142), respectively; An amplification unit (170) that amplifies the output of the RF signal combined in the above-mentioned coupler (150); A power amplifier that simultaneously implements envelope tracking and digital pre-distortion, comprising: a supply voltage modulator (180) that frequency modulates a baseband signal output from the converter (120) into a passband and inputs it to the amplifier (170).
2. In paragraph 1, A power amplifier that simultaneously implements envelope tracking and digital pre-distortion, further comprising: an antenna (190) that transmits an RF signal amplified in the amplification unit (170).
3. In paragraph 1, The above converter (120) I-DAC (121) and Q-DAC (122) that convert digital I and Q signals included in the RF signal into analog signals; A power amplifier that simultaneously implements envelope tracking and digital pre-distortion, comprising an envelope DAC (123) that converts a digital baseband signal output from an envelope shaping section (114) into an analog signal.

Description

Power amplifier simultaneously implementing envelope tracking and digital pre-distortion The present invention relates to a power amplifier that simultaneously implements envelope tracking and digital pre-distortion, and more specifically, to a power amplifier that simultaneously implements envelope tracking and digital pre-distortion, which can simultaneously implement ET and DPD algorithms by improving the efficiency of the amplifier by changing the supply voltage of the power amplifier in a power amplifier that applies digital pre-distortion technology. In power amplifiers that apply a digital pre-distortion algorithm, the supply voltage is fixed and AM-AM and AM-PM distortion characteristics occur consistently, so RF signal distortion is compensated using digital pre-distortion technology utilizing a look-up table. Envelope tracking (ET) technology aims to improve the efficiency of the power amplifier by changing the fixed supply voltage magnitude of the power amplifier to the magnitude of the actual required voltage. Figure 1 is a block diagram showing the configuration and connection structure of a typical digital pre-distortion circuit. Digital Pre-Distortion (DPD) technology aims to characterize such distortion by observing the output state of a power amplifier to determine what the desired output signal is, and then changing the input signal so that the output of the power amplifier is close to an ideal state. RF signals used in 5G mobile communication devices have the characteristics of a continuously changing output magnitude over time and a wideband. Due to these signal characteristics, the Peak to Average Power Ratio (PAPR) and linearity must be considered. However, linearity is degraded when the RF signal operates close to the saturation region of the FET, which is a key component of the power amplifier. Therefore, the average power of the power amplifier must operate with back-off from the saturation region, which inevitably leads to a decrease in power efficiency. However, when supply modulation techniques such as envelope tracking, APT (Average Power Tracking), or SPT (Symbol Power Tracking) are applied to a power amplifier, changes occur in the RF characteristics of the power amplifier. Figure 2 is a block diagram comparing the structure of a power amplifier according to the prior art and a power amplifier to which envelope tracking technology is applied. In the case of envelope tracking technology, since the AM-AM and AM-PM signal distortion characteristics in the power amplifier change depending on the change in supply voltage, there was a problem in that existing digital pre-distortion technology alone could not compensate for the signal distortion of a power amplifier to which envelope tracking technology is applied. FIG. 1 is a block diagram showing the configuration and connection structure of a conventional digital pre-distortion circuit. FIG. 2 is a block diagram comparing the structure of a power amplifier according to the prior art and a power amplifier to which envelope tracking technology is applied. FIG. 3 is a block diagram showing the structure of a power amplifier according to an embodiment of the present invention. FIG. 4 is a block diagram showing the components inside the combiner in detail. Hereinafter, with reference to the drawings, a "power amplifier that simultaneously implements envelope tracking and digital pre-distortion" (hereinafter referred to as "power amplifier") according to an embodiment of the present invention will be described. FIG. 3 is a block diagram showing the structure of a power amplifier according to an embodiment of the present invention, and FIG. 4 is a block diagram showing the components inside a coupler in detail. In the present invention, the envelope tracking technology combined with digital pre-distortion technology is a key technology for improving power efficiency, wherein a supply modulator is added to the power amplifier (100) to adjust the power supply of the power amplifier (100), and power suitable for the signal magnitude of the power amplifier (100) is accurately supplied in real time. In the case of a typical 5G communication terminal power amplifier, it has a maximum output of 23 to 26 dBm, and the supply output range of the supply voltage modulator (180) is within 5 V due to lithium-ion (Li-Ion) battery operation. However, the base station power amplifier generates a very high-output RF signal compared to the terminal power amplifier, and the Vcc power supply voltage of the power amplifier also operates at 24 to 28 V. Therefore, it is necessary to develop a supply voltage modulator capable of outputting a high voltage of 28V or higher for base station power amplifiers. The power amplifier (100) of the present invention is characterized by having a structure in which the digital pre-distortion circuit (DPD) and the envelope tracking circuit (ET) described above are combined simultaneously. The power amplifier (100) may be equi