Dual-Band RF Synthesizer
Silicon Laboratories has announced the Si4133G Dual-Band RF Synthesizer featuring settling times under 150 μs and support of the General Packet Radio Services (GPRS) requirements for GSM/DCS1800 mobile phones, enabling wireless data transfer rates that are equivalent to a V.90 modem. The synthesizer provides a complete CMOS RF synthesizer in a single low-profile, small-outline 24-pin package. It integrates three voltage-controlled oscillators (VCOs), loop filters, reference and VCO dividers and phase detectors, reducing board space requirements by 75 percent. Variables for dividers, phase detector gain settings, and power-down settings are programmable through a three-wire serial interface (Data, Clock and Enable) and a 22-bit internal shift register.
The Si4133G features a proprietary self-tuning architecture that does not require VCO modules and provides the ability to achieve the fast settling times required for GPRS. RF synthesis is performed in two bands, 900 MHz to 1.8 GHz and 750 MHz to 1.5 GHz, as well as IF synthesis from 62.5 MHz to 1.0 GHz.
The low settling time of 150 μs is maintained even when hopping from one end of the synthesizable tuning range to the other, allowing Si4133G-based products to easily meet requirements for GPRS classes 1 through 12. The unique integer-N architecture of the synthesizer provides these settling times without generating additional spurious sidebands associated with fractional-N synthesizers. The synthesizer comes standard in a low-profile, small outline, 24-pin package (TSSOP) and will be available in 28-lead chip scale package.
Silicon Laboratories Inc.
400 W. Cesar Chavez
Austin, TX, 78701
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