Amplifier Solutions
Introducion
- Provide differentiated solution for all power amplifiers for mobile communication, broadcasting, military, and satellite communication
FRTek researches and develops Power Amplifier Solutions for mobile communication BTS, DAS and repeater products, providing differentiated power amplifier which are highly reliable and strictly qualified.
FRTek has the capability of developing advanced Doherty technology applied with DPD/APD, which are the latest linearization technologies, using advanced devices (GaN & LDMOS). Through this technology, highly efficient and compact power amplifiers can be provided for mobile communication, broadcasting, military and medical applications.
The FRTek product line-up covers from 2G, 3G to 4G service including LTE-A and TD-LTE. We also develop products for Terrestrial DMB (T-DMB), satellite and military applications.
FRTek provides full customization working collaboratively with customers to balance their priorities (specs, size, cost) and utilizes the best technology for each case and comes up with the most optimal products for our customers.
Applications
Core Technology
LINEARIZATION TECHNOLOGY
1. APD Technology
Analog Pre-Distortion (APD) is a technology that improves the non-linearity characteristics of power amplifiers. APD is used to provide significantly higher efficiency compared to classical power amplifier designs. This results in making total system smaller and less power consumption.
The input and output signals of the amplifier are monitored and used to create the inverse function of the non-linearity characteristics of the amplifier. This inverse signal is then added back to the input of the amplifier to cancel out the non-linearity.
2. DPD Technology
DPD (Digital Pre-Distortion) is a technology that is widely commercialized in the base station / repeater industry. Its function is maximizing the linear range of the power amplifier by applying digital signal processing (DSP).
As mobile data traffic increases dramatically, next-generation base stations will be designed to achieve higher transmission bandwidths of up to 60 MHz or more. To linearize in the range of 60MHz bandwidth, the pre-distortion feedback loop algorithm for the linearization must treat up to the 5th order intermodulation product, resulting in a required digital bandwidth of 300 MHz. As time goes on and Moore’s Law continues, DPD will continue to become more competitive in price and efficiency than APD in multi-band, multi-path and high power systems – even with wider bandwidths.
HIGH EFFICIENCY TECHNOLOGY
1. Symmetrical Doherty Design
Doherty technology has been commercialized in power amplifiers since early 2000 to improve the power consumption of mobile communication BTS, DAS, and repeater systems.
The signal is passed through two amplifier paths (Carrier Amplifier and Peaking Amplifier) with the same peak power through both paths and then the outputs are carefully matched together.
The bias of Carrier Amplifier is set to Class AB and the bias of Peaking Amplifier is set to Class B or C. For low input power, only the Carrier Amplifier operates and the Peaking Amplifier does not operate. For maximum efficiency, the Peaking Amplifier starts to operate at the 6dB back-off point from the saturation power (Psat) of the power amplifier.
2. Asymmetrical Doherty Design
Asymmetrical Doherty technology does not use the same power Carrier Amplifier and Peaking Amplifier as Doherty, but applies different Power ratios.
The power at the Peaking Amplifier is applied about 2 ~ 3 times higher than Carrier Amplifier, and the efficiency increases at lower power as the power of Peaking Amplifier increases.
The Doherty has the maximum efficiency at the 6dB back-off point from the saturation power of the power amplifier, while the Asymmetrical Doherty has the maximum efficiency at the 7-12dB back-off point according to the power of the peaking Amplifier. Considering the PAPR of the service signal, it can be designed to have the maximum efficiency at the rated output power or lower output power of the power amplifier, but the drawback is that the cost is increased due to the high power Peaking Amplifier that is required.