Analog Devices integrated 8 GHz phase-locked loop frequency synthesizer is the RF Design Product of the Month for June 2006.

For the PDF version of this article, click here.

To simplify system design and cut costs in high-frequency wireless systems, Analog Devices has developed an integrated 8 GHz phase-locked loop (PLL) frequency synthesizer that eliminates the need for frequency doublers. Designed for wireless systems, such as those used for broadband wireless access, satellite communications, instrumentation, wireless LANs and base stations for wireless radio, the new ADF4108 is the highest-frequency PLL synthesizer currently available on the market, according to the manufacturer. The device can be used to implement local oscillators in the upconversion and downconversion sections of wireless receivers and transmitters. It consists of a low-noise digital phase frequency detector (PFD), a precision charge pump, a programmable reference divider, programmable A (6 bit) and B (13 bit) counters, and a dual-modulus prescaler (P/P +1). The A and B counters, in conjunction with the dual-modulus prescaler, implement an N divider (N = BP+A). In addition, the 14-bit reference counter (R counter) allows selectable REFIN frequencies at the PFD input. The ADF4108 has a power supply range of 3.2 V to 3.6 V and a separate charge pump supply (VP) allows extended tuning voltage in 3.3 V systems. A complete PLL can be implemented if the synthesizer is used with an external loop filter and voltage-controlled oscillator (VCO). Operating temperature range for the device is -40 °C to +85 °C.