INDUSTRY'S FIRST 1.8GHz TO 2.5GHz DIRECT CONVERSION RECEIVERS SIMPLIFY WIDEBAND WIRELESS LOCAL LOOP DESIGNS
Note to Editors: The MAX2700/MAX2701 are the industry’s only direct conversion receivers designed for wireless local loop applications. With direct conversion architecture, the IF SAW filter, RF downconverter, and IF VCO components are eliminated, allowing for single-chip integration. The reduced component count helps to significantly drive down WLL subscriber equipment cost.
SUNNYVALE, CA—May 22, 2000—Maxim Integrated Products introduces the MAX2700/MAX2701 receiver ICs, the industry’s first direct conversion receivers designed for wideband wireless local loop (WLL) systems. The direct conversion (or zero-IF) architecture eliminates one to two frequency downconversions typically found in superheterodyne systems today, helping to reduce component count and cost, and improving system reliability and manufacturing yield—key factors in driving down overall WLL subscriber equipment cost. Together with the MAX2720/MAX2721 direct I/Q transmitters, they combine to form a complete chipset solution for wideband WLL systems operating in the 1.8GHz, 1.9GHz, 2.1GHz, 2.3GHz, and 2.4GHz frequency bands with channel bandwidths exceeding 50MHz.
The MAX2700 is optimized for operation in the 1.8GHz to 2.1GHz band, whereas the MAX2701 is optimized for the 2.1GHz to 2.5GHz band. Both receiver ICs consist of three main blocks: a low-noise amplifier (LNA), a quadrature downconverter, and baseband variable gain amplifiers (VGAs). The LNA provides 17dB gain, 2.3dB noise figure, and +4dBm input IP3 at 2.4GHz. The high input IP3 helps to minimize cross modulation and gain compression due to high-level RF interference. The quadrature downconverter section consists of two highly linear double-balanced mixers driven by an external LO, a selectable LO doubler, and a wideband LO quadrature generator. The double-balanced mixers are optimized for high input IP2, IP3, and minimum added noise. The MAX2701 provides a mixer input IP2 of +38dBm and IP3 of +6dBm. The high input IP2 helps to minimize receiver desensitization due to in-band AM modulated high-level interferers. The two baseband VGAs in each channel provide 80dB of total maximum gain and >60dB of gain control. External low-pass filters connected in the baseband interstages provide the necessary channel selectivity. Integrated into the MAX2700/MAX2701 is an amplitude/gain correction loop circuit. This circuit guarantees the match between the I and Q channel amplitudes to be closer than 0.7dB.
The MAX2700/MAX2701 are also applicable to two-way MMDS and 2.4GHz ISM wideband systems. Both are available in the small 48-pin TQFP package with exposed paddle for optimum high-frequency performance. Prices start from $8.34 (1000-up, FOB USA). A fully assembled evaluation kit (MAX2700/MAX2701EVKIT) is available to help reduce design time. |
