DATA SHEET SKY72300-362: Spur-Free, 2.1 GHz Dual Fractional-N Frequency Synthesizer Applications Direct digital modulation General purpose RF systems 3 V operation 2.5G and 3G wireless infrastructure 5 V output to loop filter Broadband wireless access QFN (24-pin, 4 x 4 mm) Pb-free (MSL3, 260 C per JEDEC J- STD-020) package Low bit rate wireless telemetry Instrumentation L-band receivers Description Skyworks SKY72300-362 direct digital modulation fractional-N Satellite communications frequency synthesizer provides ultra-fine frequency resolution, fast switching speed, and low phase-noise performance. This synthesizer is a key building block for high-performance radio Features system designs that require low power and fine step size. Spur-free operation The ultra-fine step size of less than 100 Hz allows this synthesizer 2.1 GHz maximum operating frequency to be used in very narrowband wireless applications. With proper 500 MHz maximum auxiliary synthesizer temperature sensing or through control channels, the synthesizers fine step size can compensate for crystal oscillator Ultra-fine step size, 100 Hz or less or Intermediate Frequency (IF) filter drift. As a result, crystal High internal reference frequency enables large loop bandwidth oscillators or crystals can replace temperature-compensated or implementations ovenized crystal oscillators, reducing parts count and associated Very fast switching speed (e.g., below 100 s) component cost. The devices fine step size can also be used for Doppler shift corrections. Phase noise to 91 dBc/Hz inside the loop filter bandwidth The SKY72300-362 has a phase noise floor of 90 dBc/Hz up to 1800 MHz 2.1 GHz operation as measured inside the loop bandwidth. This is Software programmable power-down modes permitted by the on-chip low noise dividers and low divide ratios High-speed serial interface up to 100 Mbps provided by the devices high fractionality. Three-wire programming Reference crystals or oscillators up to 50 MHz can be used with the SKY72300-362. The crystal frequency is divided down by Programmable division ratios on reference frequency independent programmable dividers (1 to 32) for the main and Phase detectors with programmable gain to provide a auxiliary synthesizers. The phase detectors can operate at a programmable loop bandwidth maximum speed of 25 MHz, which allows better phase noise due Frequency power steering further enhances rapid acquisition to the lower division value. With a high reference frequency, the time loop bandwidths can also be increased. Larger loop bandwidths improve the settling times and reduce in-band phase noise. On-chip crystal oscillator Therefore, typical switching times of less than 100 s can be Frequency adjust for temperature compensation achieved. The lower in-band phase noise also permits the use of lower cost Voltage Controlled Oscillators (VCOs) in customer applications. Skyworks offers lead (Pb)-free RoHS (Restriction of Hazardous Substances) compliant packaging. The SKY72300-362 has a frequency power steering circuit that helps the loop filter to steer the VCO when the frequency is too fast or too slow, further enhancing acquisition time. Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 200731B Skyworks Proprietary and Confidential information Products and Product Information are Subject to Change Without Notice July 30, 2007 1 DATA SHEET SKY72300-362 FREQUENCY SYNTHESIZER The unit operates with a three-wire, high-speed serial interface. A This capability can eliminate the need for In-phase and combination of large bandwidth, fine resolution, and the three- Quadrature (I/Q) Digital-to-Analog Converters (DACs), quadrature wire, high-speed serial interface allows for a direct frequency upconverters, and IF filters from the transmitter portion of the modulation of the VCO. This supports any continuous phase, radio system. constant envelope modulation scheme such as Frequency Figure 1 shows a functional block diagram for the SKY72300-362. Modulation (FM), Frequency Shift Keying (FSK), Minimum Shift The device package and pinout for the 24-pin Quad Flat No-Lead Keying (MSK), or Gaussian Minimum Shift Keying (GMSK). (QFN) package are shown in Figure 2. Data Registers Clock Main PD/Charge Pump Main Ref Freq Aux Aux Modulation Modulation Serial MSB/LSB & Pwr-Dn/Mux Out CS Data Divider Control Dividers Divider Dividend Interface Dividend Control Mod in Modulation Mux Mux out Unit 18-Bit 10-Bit Fractional Fractional Reference Unit Unit Frequency Oscillator Fvco main Fvco aux Main Main Auxiliary Auxiliary Fvco main Divider Divider Divider Prescaler Fvco aux Fpd main Fref main Fref aux Fpd aux Main Auxiliary Phase/Freq. Phase/Freq. Fref Detector Detector and and Charge Pump Charge Pump Reference Frequency Oscillator CPout main CPout aux LD/PSmain LD/PSaux Lock Detection or Lock Detection or Power Steering Power Steering C1447 Figure 1. SKY72300-362 Functional Block Diagram Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 2 July 30, 2007 Skyworks Proprietary and Confidential information Products and Product Information are Subject to Change Without Notice 200731B