Electronic Design

Linear Mixer Blends High Performance And Speedy Basestation Design

Fewer applications are more critical and demanding than a cell-phone basestation receiver that gets bombarded with lots of signals, from the weak to the overwhelming. Coming to the rescue is Linear Technology's LT5527 RF mixer, an active downconverting mixer designed for cellular basestations.

Built for current designs as well as future 3G designs using WCDMA, the LT5527 operates from 400 MHz to 3.7 GHz. This covers the 850-MHz cellular band, the 1.9-GHz and 2.1-GHz W-CDMA and UMTS bands, and other high-performace wireless applications that operate in bands at 450 MHz and 2.4 and 3.5 GHz. The input third-order intercept point (IIP3) linearity at 1.9 GHz is 23.5 dBm. Conversion gain is 2.3 dB, and noise figure measures 12.5 dB.

RF transformers are built into the input signal and local-oscillator (LO) signal (see the figure). The input impedances are 50 (omega) single-ended, eliminating the need for separate impedance-matching circuits. The local oscillator input's built-in low-noise buffer enables operation at a ­3-dBm LO drive level. This helps solve the challenges of RF isolation and reduces the need for external filtering. The LO to RF input leakage is ­44 dBm.

The LT5527 comes in a 16-pin, 4- by 4-mm QFN package. It costs $5.80 in 1000-unit quantities.

Linear Technology Corp.
(408) 432-1900

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