Multiband WiMAX RF ICs Provide Global Spectrum Coverage
PMC-Sierra has a new line of WiMAX radio chips designed for CPE and NICs in expanding WiMAX coverage. The chips can also work in laptop cards and USB dongles as well as femto and pico basestations. The challenge in producing a transceiver for WiMAX is the enormous difference in worldwide frequency assignments. Designated the WiZIRD family, these transceiver chips are available in models that cover the 450- to 928-MHz, 2.3- to 2.7-GHz, 3.3- to 3.8-GHz, and 4.9- to 5.95-GHz ranges.
With global WiMAX frequency assignments all over the place worldwide, these RF chips will let any vendor target any international market. The 3.3- to 3.8-GHz bands are the most widely used in the world, with the 2.3- to 2.7-GHz bands popular in the U.S. and in some Asian countries. These ICs are designed to work with a number of commonly available baseband WiMAX chips, such as those from Sequans Communications.
The WiZIRD RF offer a direct conversion ZIF design. Their patent-pending integrated dc offset algorithm performs dc offset correction every frame. They also provide integrated ADCs and DACs, flexible baseband interface options, and integrated transmitter baluns.
The baseband interface is a standard JEDEC JESD207. The chips support the IEEE 802.16-2004 fixed and 802.16e-2005 mobile standards. Furthermore, designers can configure the channel bandwidths to the most popular standards of 3.5, 5, 7, 8.75, 10, 14, and 20 MHz.
An innovative harmonic canceling technique is used to achieve extremely linear output at high power levels. For example, the transmitter can deliver 64QAM (quadrature amplitude modulation) at 0-dBm output with an outstanding EVM rating. All of the chips support some form of MIMO.
The PM8850 provides 2Tx/2Rx MIMO on 2.3 to 2.9, 3.3 to 3.8, or 4.9 to 5.95 GHz. The PM8851 provides 1Tx/2Rx MIMO on 2.3 to 2.9, 3.3 to 3.8, or 4.9 to 5.95 GHz. The PM8870 provides 2Tx/2Rx on 2.3 to 2.9 and 3.3 to 3.8 GHz or 450 to 928 MHz. And, the PM8871 provides 1Tx/2Rx on 2.3 to 2.9 and 3.3 to 3.8 GHz or 450 to 928 MHz.
Each IC supports the standard TDD multiple access mode, while the PM8870 and PM8871 will also handle FDD. The WiZIRD ICs come in a 108 pin MLF/QFN package and are made with the latest CMOS technology. The chips are sampling now. Reference designs, drivers and other support documentation are available.
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