GENERAL DESCRIPTION

The ADF4108 frequency synthesizer can be used to implement local oscillators in the up-conversion and down-conversion sections of wireless receivers and transmitters. It consists of a low noise digital PFD (phase frequency detector), a precision charge pump, a programmable reference divider, programmable A and B counters, and a dual-modulus prescaler (P/P + 1). The A (6-bit) and B (13-bit) counters, in conjunction with the dual modulus prescaler (P/P + 1), implement an N divider (N = BP + A). In addition, the 14-bit reference counter (R counter), allows selectable REFIN frequencies at the PFD input. A complete phase-locked loop (PLL) can be implemented if the synthesizer is used with an external loop filter and voltage controlled oscillator (VCO). Its very high bandwidth means that frequency doublers can be eliminated in many high frequency systems, simplifying system architecture and reducing cost.

FEATURES

8.0 GHz bandwidth

3.2 V to 3.6 V power supply

Separate charge pump supply (VP) allows extended tuning voltage in 3.3 V systems

Programmable, dual modulus prescaler 8/9, 16/17, 32/33, or 64/65

Programmable charge pump currents

Programmable antibacklash pulse width

3-wire serial interface

Analog and digital lock detect

Hardware and software power-down mode

Loop filter design possible with ADIsimPLL

APPLICATIONS

Broadband wireless access

Satellite systems

Instrumentation

Wireless LANs

Base stations for wireless radio