Microwave PLL synthesiser eliminates frequency-doubling in broadband applications

October 12, 2011 // By Paul Buckley
Analog Devices, Inc., has introduced a PLL (phase-locked loop) frequency synthesiser that can be used to implement local oscillators as high as 18 GHz in the up-conversion and down-conversion sections of wireless receivers and transmitters.

The high bandwidth of the ADF41020 allows designers to potentially eliminate a frequency-doubler stage, which simplifies system architecture and reduces cost in applications including microwave point-to-point and multi-point radios, wireless infrastructure equipment, VSAT (very small aperture terminal) radios, semiconductor test equipment, radar applications and private mobile radios.

With an operating bandwidth up to 18 GHz, this is claimed to represent the highest frequency PLL available on the market today.

The ADF41020 PLL frequency synthesiser consists of a low-noise, digital phase-frequency detector, a precision charge pump, a programmable reference divider and high-frequency programmable feedback dividers. A complete synthesiser can be implemented if the PLL is used with an external loop filter and VCO (voltage controlled oscillator). The PLL can be used to drive external microwave VCOs via an active loop filter. The pin-out matches very closely the pinout of the ADF4106/7/8 family of integer-N PLLs, meaning only a minor layout change is required when updating a design to take advantage of the much wider bandwidth.

The ADF41020 PLL frequency synthesiser is software compatible with the existing ADF4106 , ADF4107 and ADF4108 PLLs and is well-suited for use with a variety of products including the ADP150 LDO (low dropout regulator) and the OP184 operational amplifier.
Availability and Pricing

Samples of the ADF41020 PLL frequency synthesizer packaged in 20-lead LFCSP are available now and priced $12.77 each in 1,000-unit quantities.

More information about the ADF41020 PLL frequency synthesizer at