Improvement of base station performance and wireless service quality

Analog Devices announced a phased-locked loop (PLL) synthesizer with an integrated voltage-controlled oscillator (VCO) that can improve the performance of wireless base stations and the quality of wireless services for mobile network operators.

The new ADF4355 PLL synthesizer equipped with a VCO can operate at up to 6.8 GHz, which significantly extends the range of carrier frequencies currently used in the industry. Designing a wireless base station using the ADF4355 PLL synthesizer increases the frequency range and lowers VCO phase noise, thereby increasing the wireless service provider's call throughput and wireless telephone coverage, and expanding the number of serviceable users per base station without significant additional costs.

Using this allows for higher frequency bands, so manufacturers of P2P/P2M (point-to-point/point-to-multipoint) microwave links, satellite/VSAT systems, industrial, test, and measurement systems, and other wireless equipment can likewise experience a similar increase in throughput.

In frequency generation applications for wireless and industrial applications, VCO phase noise performance plays a critical role in determining the overall system performance of RF signal transmission and reception, so selecting a PLL synthesizer to use for the RF local oscillator (LO) is a major consideration when designing the system.

ADI's ADF4355 broadband PLLVCO synthesizer meets the demanding VCO phase noise requirements of frequency generation applications and offers superior cost-effectiveness compared to other PLL devices used in the smallest-in-class 5mm x 5mm LFCSP package. Based on this combination of performance, designers can achieve the lowest possible phase noise, extend the frequency range, reduce the footprint, and extend the temperature-dependent operating range to reduce risk.

The output frequency range of the integrated VCO of the ADF4355 PLL synthesizer is 3.4 to 6.8 GHz. The VCO frequency can be divided by 1, 2, 4, 8, 16, 32, or 64 to generate frequencies up to 6.8 GHz without gaps from a minimum RF output frequency of 54 MHz. In applications requiring noise suppression, the RF output stage includes a mute function controllable via both pins and software. The ADF4355 supports both fractional-N and integer-N modes and provides accurate mode frequency operation regardless of the reference input frequency with 38-bit modulus resolution.

Control of all on-chip registers is performed via a simple 3-wire interface. The ADF4355 operates with analog and digital input power supplies of 3.15 to 3.45 V, and the charge pump and VCO power supply is 4.75 to 5.25 V. The ADF4355 also supports hardware and software power-down modes.

Key Features of the ADF4355 Broadband, Ultra-Low Noise Synthesizer

• 54MHz~6.8GHz continuous frequency range
• Ultra-low VCO phase noise: -144dBc/Hz (typ) at 1.7GHz, 1MHz offset
• High resolution 38-bit modulus
• Operates without reprogramming at -40°C to +85°C
• Dual differential output
• Support for ADIsimPLL circuit design and virtual evaluation software
• Integrated RMS Jitter: ~150fs