Analog Devices' VCO-integrated PLL frequency synthesizers improve base station performance and wireless service quality

     Analog Devices introduces the ADF4355, a phase-locked loop (PLL) frequency synthesizer with integrated voltage controlled oscillator (VCO) that mobile network operators can use to improve cell base station performance and wireless service quality. The ADF4355, a new PLL synthesizer with VCO integration, operates at frequencies up to 6.8 GHz, which provides considerable margin for the industry's current carrier frequencies. Designed for use in cellular base stations, wireless service providers can take advantage of the new PLL frequency synthesizer's high operating frequency and low VCO phase noise to improve call throughput and cellular signal coverage, enabling each base station to serve more users at no significant increase in cost. For manufacturers of point-to-point/point-to-multipoint microwave links, satellite /VSAT systems, industrial and test measurement systems, and other wireless devices, the device's high frequency band also improves throughput.

     In wireless and industrial frequency generation applications, VCO phase noise performance plays a key role in determining the overall system performance of RF signal transmission and reception, and selecting the right PLL frequency synthesizer for RF local oscillator (LO) is an important consideration in system design. ADI's ADF4355 wideband PLLVCO frequency synthesizer fully meets the demanding VCO phase noise requirements of frequency generation applications, is cost-competitive, can replace other PLL devices, and its 5mm × 5mm LFCSP package is the smallest in its class. The combination of these characteristics allows designers to ensure that phase noise is as low as possible, extend the frequency range, reduce the size, and expand the operating temperature range, thereby reducing risk.

     The output frequency range of the integrated VCO of the ADF4355 PLL frequency synthesizer is 3.4 GHz to 6.8 GHz. The VCO frequency can be divided 1, 2, 4, 8, 16, 32, or 64, so designers can generate RF output frequencies as low as 54 MHz, which enables the ADF4355 to cover a continuous frequency range of 54 MHz to 6800 MHz without voidage. For applications that require noise isolation, the RF output stage has a mute feature that can be muted through both pin and software control. The ADF4355 can operate in fractional N or integer N division mode and has a 38-bit modular resolution, enabling precise frequency operation mode independent of the reference input frequency.

     All on-chip registers are controlled through a simple three-wire interface. The ADF4355 operates with analog and digital power supplies from 3.15 V to 3.45 V, with charge pumps from 4.75 V to 5.25 V and VCO power supplies. In addition, the ADF4355 has built-in hardware and software power-saving modes.