Analog Devices Enhances RF/IF Signal Chain Performance

30th October 2008

Analog Devices

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Datasheet

Analog Devices has introduced the ADF4350 synthesizer with on-chip VCO (voltage-controlled oscillator) and PLL (phase-locked loop), which is the industry’s first fully integrated synthesizer to operate over an exceptionally wide continuous frequency range. Also, ADI introduced a family of highly integrated active and passive mixers that are ideally suited for use in diversity communications applications. The active ADL5802 and passive ADL5356, ADL5358 and ADL5360 dual-channel diversity mixers expand ADI’s portfolio of main and diversity products and when coupled with the ADF4350 provide a highly integrated two-chip diversity down conversion solution for cellular base stations, satellite communications, and point-to-point microwave radio equipment.

The ADF4350 integrated synthesizer provides designers with a single, low phase-noise solution supporting a continuous tuning range from 137.5 MHz to 4.4 GHz. Alternative approaches require as many as 10 individual VCO/PLL combinations. The VCO in ADI’s new ultra-broadband, fully integrated synthesizer features phase-noise of –137 dBc/Hz at a 1-MHz offset when operating at 2.1 GHz, and –155 dBc/Hz at a 1-MHz offset when operating at 137.5 MHz. This corresponds to an integrated rms phase error of 0.36 degrees at 2.1 GHz and 0.02 degrees at 137.5 MHz. The ADF4350 provides two RF output ports and enables the user to digitally program the output power level.

Unlike competing synthesizers, the ADF4350 supports both integer-N and fractional-N operating modes, allowing the user to determine the optimal spur and phase-noise performance via software controls for optimal performance and faster time to market.

ADI’s new mixer family includes the ADL5802 wideband active device, which provides high linearity and modest gain in the industry’s smallest package footprint. The family also includes the ADL5356, ADL5358 and ADL5360 band-specific passive mixers, which achieve high linearity and a low-noise figure with integrated IF (intermediate frequency) amplifiers and offer higher gain compared to other active and competing passive devices.

The ADL5802 dual active mixer achieves an IIP3 (third-order input intercept point) of 27 dBm and a single sideband noise figure of 11 dB with a conversion power gain of 1.5 dB within a 4 mm × 4 mm LFCSP (lead-frame chip-scale package). For high linearity applications, the ADL5802 dissipates less than 1 W from a 5-V power supply. The ADL5802 uses high linearity doubly-balanced active mixer cores together with integrated LO (local oscillator) buffer amplifiers to provide high dynamic-range frequency conversion from 300 MHz to 6 GHz. A bias-adjust feature allows the input linearity, single sideband noise figure, and dc current to be optimised using a single control pin.

The ADL5356, ADL5358 and ADL5360 dual passive mixers with integrated IF amplifiers and integrated RF (radio frequency) balun achieve an IIP3 of 26 dBm, a single sideband noise figure of less than 10 dB, and an industry leading 10-dBm blocker noise figure of 16.5 dB. The passive mixers with IF amplifiers provide a conversion power gain of 8.5 dB to 9.5 dB within a small 6 mm x 6 mm LFCSP footprint. The 5-V (nominal) ADL5356, ADL5358, and ADL5360 can also be operated on a 3.3-V supply voltage for power-conscious applications.

The new active and passive mixers are well matched to ADI’s ADF4350 synthesizer. In addition, the ADF4350 provides an ideal LO source for Analog Devices’ ADL538X demodulators and ADL537x modulators. Together these products provide an ideal RF receive signal path when combined with Analog Devices’ AD837X family of high dynamic range variable gain amplifiers and Analog Devices’ ADL552X low-noise RF amplifiers.