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Mixers improve basestation performance

Linear Technology announces the LTC554x family of four new high dynamic range down-converting mixers designed to enhance receiver sensitivity and robustness in the 700MHz to 4GHz wireless infrastructure frequency range. The LTC554x mixers offer outstanding IIP3 (input third-order intercept) of 26dBm, low noise figures of 9-10dB and high conversion gain of 8dB, enabling excellent dynamic range performance for both main receivers and digital predistortion receivers. The LTC554x family of mixers provides best-in-class capability to maintain a low noise figure in the presence of strong blocking interferers, and significantly enhancing receiver sensitivity and robustness. Unlike other mixers in their class, the LTC554x family operates on a single 3.3V supply without compromising performance, while reducing power consumption by 34% compared to the closest competing solution.

The LTC554x mixers are designed to satisfy the requirements of nascent 4th generation LTE (Long-Term Evolution) cellular and WiMAX basestations, as well as 3G CDMA, WCDMA, TD-SCDMA, UMTS and GSM/EDGE platforms. The mixers’ robust performance also enhances other wireless systems such as point-to-point microwave systems, cellular repeaters, public safety radios and military communication systems.

The LTC554x mixers contain an integrated IF amplifier, LO buffer, LO switch and RF balun transformers. Each mixer’s RF input is single ended, 50 matched. Two single-ended LO inputs with high isolation are provided for frequency hopping applications. Each LO input is also single ended, always 50 matched regardless of whether the mixer is active or powered down to avoid unlocking of the PLL (Phased-Lock Loop). The LO input requires only 0dBm drive level. All of these features facilitate a compact solution with minimal external components.

The LTC554x mixers have identical pinouts, allowing designers to share PC board layouts across multiple platforms operating in different frequency bands. This helps users reduce total ownership costs and speed time to market. The mixers’ pinouts are also similar to common industry footprints and pinouts, allowing ease of adoption while improving performance and reducing power consumption.

The LTC554x mixers operate on a single 3.3V supply, drawing a supply current of 200mA. The LTC554x devices have a power-down feature with turn-on and turn-off time of 2s and 3s, respectively. When disabled, the ICs consume a maximum of 500A. The products are offered in a 20-lead, 5mm x 5mm QFN surface mount package. Production will begin in November 2009, starting with the release of the LTC5541, followed by LTC5543, LTC5540 and the LTC5542. All products are sampling now and will be available in production quantities by February 2010. The LTC5541 is priced starting at $6.50 each.