DATA SHEET SKY72300-21: Spur-Free, 2.1 GHz Dual Fractional-N Frequency Synthesizer Applications x Direct digital modulation x General purpose RF systems x 3 V operation x 2.5G and 3G wireless infrastructure x 5 V output to loop filter x Broadband wireless access x EP-TSSOP (28-pin, 9.7 x 6.4 x 1.1 mm) package (MSL3, 260 q C per JEDEC J-STD-020) x Low bit rate wireless telemetry x Instrumentation x L-band receivers Description Skyworks SKY72300-21 direct digital modulation fractional-N x 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. x Spur-free operation The ultra-fine step size of less than 100 Hz allows this synthesizer x 2.1 GHz maximum operating frequency to be used in very narrowband wireless applications. With proper x 500 MHz maximum auxiliary synthesizer temperature sensing or through control channels, the synthesizers fine step size can compensate for crystal oscillator x Ultra-fine step size, 100 Hz or less or Intermediate Frequency (IF) filter drift. As a result, crystal x 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 x Very fast switching speed (e.g., below 100 P s) component cost. The devices fine step size can also be used for Doppler shift corrections. x Phase noise to 91 dBc/Hz inside the loop filter bandwidth 1800 MHz The SKY72300-21 has a phase noise floor of 90 dBc/Hz up to 2.1 GHz operation as measured inside the loop bandwidth. This is x Software programmable power-down modes permitted by the on-chip low noise dividers and low divide ratios x High-speed serial interface up to 100 Mbps provided by the devices high fractionality. x Three-wire programming Reference crystals or oscillators up to 50 MHz can be used with x Programmable division ratios on reference frequency the SKY72300-21. The crystal frequency is divided down by independent programmable dividers (1 to 32) for the main and x 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 x 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 x On-chip crystal oscillator improve the settling times and reduce in-band phase noise. Therefore, typical switching times of less than 100 s can be x 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. TM Innovation to Go Now available for purchase online. Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 101217N Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice September 11, 2009 1 DATA SHEET SKY72300-21 FREQUENCY SYNTHESIZER The SKY72300-21 has a frequency power steering circuit that This capability can eliminate the need for In-phase and helps the loop filter to steer the VCO when the frequency is too Quadrature (I/Q) Digital-to-Analog Converters (DACs), quadrature fast or too slow, further enhancing acquisition time. upconverters, and IF filters from the transmitter portion of the radio system. The unit operates with a three-wire, high-speed serial interface. A combination of large bandwidth, fine resolution, and the three- Figure 1 shows a functional block diagram for the SKY72300-21. wire, high-speed serial interface allows for a direct frequency The device package and pinout for the 28-pin Exposed Pad Thin modulation of the VCO. This supports any continuous phase, Shrink Small Outline Package (EP-TSSOP) are shown in Figure 2. constant envelope modulation scheme such as Frequency Modulation (FM), Frequency Shift Keying (FSK), Minimum Shift Keying (MSK), or Gaussian Minimum Shift Keying (GMSK). Data Registers Clock Main PD/Charge Pump Modulation Main Modulation Ref Freq Aux Aux 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. SKY72300-21 Functional Block Diagram Clock 1 28 CS 2 27 Mod in Data Mux out 3 26 VCCdigital 4 25 VSUBdigital GNDdigital 5 24 GNDcml VCCcml aux 6 23 VCCcml main VCCvco aux Fvco main 7 22 Fvco aux Fvco main 8 21 GNDcp aux LD/PSmain 9 20 CPout aux 10 19 VCCcp main VCCcp aux 11 18 CPout main LD/PSaux GNDcp main 12 17 GNDxtal Xtalacgnd/OSC 13 16 VCCxtal 14 15 Xtalin/OSC Xtalout/NC C1412 Figure 2. SKY72300-21 Pinout, 28-Pin EP-TSSOP (Top View) Skyworks Solutions, Inc. Phone 781 376-3000 Fax 781 376-3100 sales skyworksinc.com www.skyworksinc.com 2 September 11, 2009 Skyworks Proprietary Information Products and Product Information are Subject to Change Without Notice 101217N