CMOS power amplifier technology

Annual production of more than 10 million mobile phone handset market in the semiconductor industry has become the most competitive areas. This argument has been: such as gallium arsenide (GaAs), lateral diffusion MOS (LDMOS) or silicon germanium (SiGe) bipolar CMOS (BiCMOS) process to less intensive and other special tip of the geometric accuracy and design manufacturers can provide Teachers needed for short-term cost advantage and linear modulation. However, economies of scale inherent in CMOS industry has been driven by its massive investment, so the scale has been and will continue to be ahead of other technology products.

For example, earlier by the Infineon, NXP and Skyworks supply business such as specialized manufacturing BiCMOS technology transceiver modules, these modules use CMOS realization of a very long time, and in some occasions it is integrated into the system-chip mobile phone within the main processor. Designers have repeatedly found that although the process by demanding circuit module may bring challenges, but long-term point of view, using standard CMOS analog module will be rewarded. However, CMOS technology has been unable to successfully enter the power amplifier (PA) module in the field, while the amplifier is a key component of the phone.

Until now, PA Development and are based on GaAs or LDMOS technology specialist accompanied by mixed-module package technology, and overall it is a costly manufacturing process, so that the cost of PA occupy a large mobile phone. PA required special semiconductor process used to provide high breakdown voltage, high gain and high frequency transistor components. Hybrid packaging technology provides a high-Q passive components to generate a 50Ω matching circuit. To achieve using standard CMOS PA, means that designers must face is not enhanced transistors and high-Q passive components of the situation, so that the development of fully integrated PA has become extremely challenging.

Recently there is a possibility of using the CMOS manufacturing process PA of new technology, so, PA can be placed in a simple plastic package. Distributed Active Transformer (DAT) technology as it claimed, the geometric structure supports the use of relatively low Q value of the semiconductor metal to provide transformer-based matching circuit, thereby eliminating the need for a module package. The PA core distributed to several blocks and then integrates the power transformer structure and the way many other patented technology, you can save the high breakdown voltage transistors.

CMOS power amplifier technology
Figure 1: The CMOS amplifier-based DAT technology is used in standalone GPRS phone.

DAT invention is based on the California Institute of Technology based on research results. Axiom Microdevices company has improved the technology has achieved commercial production DAT PA, and General Packet Radio Service (GPRS) PA product of the device was improved to address issues such as noise and receiver with high-voltage battery needs work group under the specific applications.

GaAs and other products with different, because the kernel uses CMOS to achieve power, so the bias and adjust the GPRS type PA power for a small signal control circuitry can be integrated with the main power stage on the same die, thereby further reducing costs. PA also support the integration of the kernel of linear modulation schemes to provide greater flexibility. Traditionally, designers have been using one of the following two methods: a linear modulator and PA's "mandatory law"; the other is more advanced "envelope reconstruction" method, then non-linear, high the PA to become the core polarization modulator.

The latter method, the use of traditional building techniques PA will bring serious challenges. For example, using a special process to achieve the PA core temperature and process variations on the response and the linear circuit is different. This usually causes the most unreasonable demands, that the end user or the mobile phone manufacturers need to increase the factory calibration time to compensate, thus increasing costs. On the contrary, if the PA controller integrated with the kernel on the same die, it will provide incentives to monitor or control the multi-point access. Thus, when designers develop the best performance and cost structure of the sending architecture, will have more choices.

The next step is to be expected that the development of PA and other components within mobile phone for further integration, such as CMOS technology has been adopted to achieve the above-mentioned base band and transceiver modules. A large number of shipping companies from Axiom AX502 device can be seen, based on DAT's CMOS amplifier technology used in a separate GPRS-product is feasible. It also has the possibility of further integration, to help the industry continue to meet the manufacturers and designers of the smaller and more cost-effective chipset demand, and to provide more.