Analog Devices' PLL with VCO synthesizer improves base station performance

Analog Devices Inc. introduced a phased-locked loop (PLL) synthesizer with integrated voltage-controlled oscillator (VCO) that allows mobile network operators to improve cellular base station performance and the quality of wireless service. The new ADF4355 PLL with VCO synthesizer operates up to 6.8 GHz, a frequency band that allows significant margin to industry's current carrier frequencies. When designed into cellular base stations, the new PLL synthesizer's higher frequency and lower VCO phase noise enables wireless service providers to increase call throughput and cell phone coverage and service more users per base station at no significant additional cost. The device's higher frequency band offers similar throughput advances for makers of point-to-point/point-to-multipoint microwave links, satellite/VSAT systems, industrial and test and measurement systems as well as other wireless equipment.

In frequency generation applications for wireless and industrial applications, where VCO phase-noise performance plays a pivotal role in determining the overall system performance of the RF signal transmission and receive, the choice of PLL synthesizer for the RF local oscillator (LO) is a key system design consideration. ADI's ADF4355 wideband PLLVCO synthesizer meets the exacting VCO phase noise requirements for frequency generation applications while delivering a cost-competitive alternative to other PLL devices in a smallest-in-class 5mm × 5mm LFCSP package. This combination of features allows designers to reduce risk by ensuring the lowest possible phase noise, extending frequency coverage, shrinking footprint and increasing operating range across temperature.

The ADF4355 PLL synthesizer's integrated VCO has an output frequency ranging from 3.4 to 6.8 GHz. The VCO frequency is connected to divide by 1, 2, 4, 8, 16, 32, or 64 circuits, which allows the designer to generate RF output frequencies as low as 54 MHz, thereby allowing the ADF4355 to cover a continuous range from 54 to 6800MHz with no gaps. For applications that require noise isolation, the RF output stage features a mute function that is both pin and software controllable. The ADF4355 can operate in either fractional-N or integer-N mode and with 38-bit modulus resolution, offers exact mode frequency operation, independent of reference input frequency.

Control of all on-chip registers is through a simple 3-wire interface. The ADF4355 operates with analog and digital power supplies ranging from 3.15 to 3.45 V, with charge pump and VCO supplies from 4.75 to 5.25 V. The ADF4355 also contains hardware and software power-down modes.

ADF4355 Wideband, Ultra-Low-Noise Synthesizer Key Features: