In the process of moving towards 4G mobile phones, the biggest challenge for portable system design engineers is to support the existing multiple mobile communication standards, including GSM, GPRS, EDGE, UMTS, WCDMA and HSDPA, while supporting 100Mb. /s ~ 1Gb / s data rate and support for OFDMA modulation, support for MIMO antenna technology, and even support VoWLAN networking, therefore, in the process of RF signal chain design, how to reduce the power consumption of RF power amplifier and improve efficiency has become One of the focus of competition in the semiconductor industry. At present, the industry development presents three technical routes. This article makes a brief comparison of these three technical routes.
Incremental integration to increase PA efficiency by using ultra-CMOS technology
UltraCMOS uses SOI technology to deposit a thin layer of silicon on an insulating sapphire substrate. Like CMOS, UltraCMOS offers low power consumption, good manufacturability, repeatability, and scalability. It is an easy-to-use process that supports IP block multiplexing and higher integration.
Unlike CMOS, UltraCMOS offers comparable or even better performance than GaAs or SiGe technology commonly used in cell phones, RF and microwave applications. Although both UltraCMOS and pHEMT GaAs offer the same level of small signal performance and comparable grid on-resistance, UltraCMOS offers superior linearity and ESD performance over GaAs or SiGe.
For more complex applications, such as the latest multi-mode, multi-band handsets, choosing the right technology is even more critical. For example, in these applications, the antenna must be able to cover the 800 to 2200 MHz band, and the switch must be able to manage up to eight high-power RF signals, while also having low insertion loss, high isolation, excellent linearity, and low Power consumption. Proper process technology can improve the availability of technology options, thereby improving the performance of antennas and RF switches, ultimately improving overall device performance. More importantly, if engineers use the same process technology throughout the design, they can achieve higher levels of integration.
For example, Peregrine's latest advancement in UltraCMOS RFICs is the introduction of SP6T and SP7T antenna switches. These 3GPP-compliant switches meet WCDMA and GSM requirements, enabling design engineers to use a set of RF circuits in a WCDMA/GSM-compatible handset and achieve industry-leading performance. The SP6T and SP7T antenna switches use Peregrine's HaR technology to achieve an excellent index of -85dBc for the second harmonic, -83dBc for the third harmonic, and -111dBm for the third-order intermodulation distortion (IMD3) at 2.14GHz.
The two most power-hungry parts of cell phone design are the baseband processor and RF front end. The power amplifier (PA) consumes most of the power in the RF front end. The key to achieving low power consumption is to make other circuits in the RF front end consume as little power as possible without affecting the operation of the PA. In the current selection, the GaAs switch with decoder absorbs 600μA, but in a typical RF front-end application, the UltraCMOS SP7T switch only sinks 10μA, which can significantly reduce the power consumption of the RF front-end. The efficiency of the RF power amplifier.
Companies that manufacture RF power amplifiers in CMOS include: Infineon, Freescale, Silicon Labs, Peregrine, and Jazz Semiconductor.
Low power consumption and high efficiency of power amplifiers with InGaP process
Many of the advantages of InGaP HBT (heterojunction bipolar transistor) technology make it ideal for high frequency applications. InGaP HBTs are made of GaAs, which is the most commonly used underlayer material for RF ICs in the RF field. The reasons are: 1. The electron mobility of GaAs is about 6 times higher than that of silicon as a CMOS substrate material; 2. The GaAs substrate is semi-insulating, while the substrate in CMOS is conductive. The higher the live mobility, the higher the operating frequency of the device.
A semi-insulating GaAs substrate allows for better signal isolation on the IC and uses less passive components. This advantage cannot be achieved if the substrate is conductive. In CMOS, due to the high conductivity of the substrate, it is difficult to construct functional microwave circuit components such as high Q inductors and low loss conductive lines. Although these difficulties can be overcome to some extent, they must be achieved by using various non-standard processes in IC assembly, which will increase the manufacturing cost of CMOS devices.
nGaP is especially suitable for high frequency applications that require a fairly high power output. Improvements in the InGaP process have led to higher yields and a higher level of integration, allowing the chip to integrate more functions. This simplifies system design, reduces raw material costs, and saves board space. Some InGaP PAs also use a multi-chip package that includes CMOS control circuitry. Today, the front-end WLAN module with integrated PA and low noise amplifier (LNA) at the receiving end combined with RF switches is available in a compact package. For example, the InGaP-Plus process proposed by ANADIGICS can integrate bipolar transistors and field effect transistors on the same InGaP chip. This technology is being used in new CDMA and WCDMA power amplifiers with improved size and PAE (power increase efficiency).
Comparison of RF CMOS PA and GaAs PA
Currently, most mobile phone PAs use GaAs and InGaP HBT technology, and only a small part is manufactured using RF CMOS technology. Compared to GaAs devices, RF CMOS technology enables higher levels of integration and lower cost.
However, it is not ideal for all consumer electronics products. For example, the wireless network and mobile phone market are dominated by GaAs PA because it can support high frequency and high power applications and is highly efficient. On the other hand, RF CMOS PA dominates Bluetooth and ZigBee applications because it typically runs at lower power and performance requirements are less demanding.
Currently, for high-performance PA applications, GaAs is still the main technology, and only it can meet the demanding performance requirements of most high-end mobile phones and wireless network equipment. In terms of integration, if you want to integrate into transceivers, basebands, and PAs, you need a new silicon process. However, the industry's trend in this regard is to continue to separate the PA and transceiver from each other, using different packages, and implementing such integration in GaAs.
Data Acquisition Digital Potentiometers
Shenzhen Kaixuanye Technology Co., Ltd. , https://www.iconlinekxys.com