Milpitas, Calif. Linear Technology has introduced a high-dynamic range active upconverting mixer that is designed to replace passive mixers. The LT5579 offers a wide frequency range of 1.5 GHz to 3.8 GHz, which covers the 1.9-GHz cellular bands as well as the 2.6-GHz and 3.5-GHz WiMAX frequency bands. The LT5579 targets current and next-generation wireless transmitters in basestations including GSM/EDGE, CDMA, CDMA2000, W-CDMA / UMTS and LTE.
The LT5579 operates from a single 3.3-V supply. Typical quiescent supply current is
226 mA. At 2.14 GHz, the LT5579 device offers 27.3 dBm output IP3 linearity and 9.9 dB noise figure to deliver an outstanding transmitter dynamic range. The device integrates local oscillator (LO) buffers, requiring only -1 dBm to drive the LO port, while offering low -35 dBm LO-to-RF leakage.
The LT5579's active, double-balanced design is said to provide several cost-saving benefits. The mixer features 2.6 dB of conversion gain, which is said to be the highest in its class. In comparison to alternative passive mixers with a typical 8 dB conversion loss, this 10 dB or more gain advantage eliminates the cost of an extra stage of high power, high linearity RF amplifier, said Linear.
Secondly, unlike many mixers on the market, the LT5579 can be driven with high signal levels at as much as -5 dBm without elevating its output noise floor above-158 dBm/Hz. This feature enables users to drive the transmitter harder while preserving its dynamic range performance, said Linear.
In addition, passive mixers have poor LO leakage to the RF output, which is challenging to control, requiring multiple stages of RF filters to achieve adequate suppression, said Linear. The LT5579's double-balanced design results in -35 dBm LO leakage at the device's RF output, reducing the external filter stages.
The device's performance at higher frequencies also supports a wide range of wireless broadband access equipment such as WiMAX or WiBro at 2.7 GHz and 3.5 GHz, cable CMTS and distribution systems, military radios, digital video broadcast systems, 2.4-GHz ISM band transmitters, test instrumentations, micro-cells, pico-cells and wireless repeaters.
The LT5579 integrates RF transformers at both its RF output and LO input to provide differential to single-ended conversion at both ports. This simplifies system design while eliminating or significantly reducing external matching components, said Linear Technology. The device comes in a 24-lead 5 x 5-mm QFN surface-mount package.
Pricing: Starts at $5.50 each in quantities of 1,000.
Availability: From stock.
Linear Technology, www.linear.com