SKY72300-21 SKYWORKS | Alldatasheet
Document overview
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Technical content
Features
x2.1 GHz maximum operating frequency x500 MHz maximum auxiliary synthesizer xUltra-fine step size, 100 Hz or less xHigh internal reference frequency enables large loop bandwidth implementations xVery fast switching speed (e.g., below 100 Ps) xPhase noise to –91 dBc/Hz inside the loop filter bandwidth @ 1800 MHz xSoftware programmable power-down modes xHigh-speed serial interface up to 100 Mbps xThree-wire programming xProgrammable division ratios on reference frequency xPhase detectors with programmable gain to provide a programmable loop bandwidth xFrequency power steering further enhances rapid acquisition time xOn-chip crystal oscillator xFrequency adjust for temperature compensation Skyworks offers lead (Pb)-free RoHS (Restriction of Hazardous Substances) compliant packaging. Innovation to GoTM Now available for purchase online. xDirect digital modulation x3 V operation x5 V output to loop filter xEP-TSSOP (28-pin, 9.7 x 6.4 x 1.1 mm) package (MSL3, 260 qC per JEDEC J-STD-020)
Description
Skyworks SKY72300-21 direct digital modulation fractional-N 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 system designs that require low power and fine step size. The ultra-fine step size of less than 100 Hz allows this synthesizer to be used in very narrowband wireless applications. With proper temperature sensing or through control channels, the synthesizer’s fine step size can compensate for crystal oscillator or Intermediate Frequency (IF) filter drift. As a result, crystal oscillators or crystals can replace temperature-compensated or ovenized crystal oscillators, reducing parts count and associated component cost. The device’s fine step size can also be used for Doppler shift corrections. 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 permitted by the on-chip low noise dividers and low divide ratios provided by the device’s high fractionality. Reference crystals or oscillators up to 50 MHz can be used with the SKY72300-21. The crystal frequency is divided down by independent programmable dividers (1 to 32) for the main and auxiliary synthesizers. The phase detectors can operate at a maximum speed of 25 MHz, which allows better phase noise due to the lower division value. With a high reference frequency, the loop bandwidths can also be increased. Larger loop bandwidths improve the settling times and reduce in-band phase noise. Therefore, typical switching times of less than 100 s can be achieved. The lower in-band phase noise also permits the use of lower cost Voltage Controlled Oscillators (VCOs) in customer applications.
DATA SHEET • SKY72300-21 FREQUENCY SYNTHESIZER 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 • Sep tember 11, 2009 3 Technical Description The SKY72300-21 is a fractional-N frequency synthesizer using a '6 modulation technique. The fractional-N implementation provides low in-band noise by having a low division ratio and fast frequency settling time. In addition, the SKY72300-21 provides arbitrarily fine frequency resolution with a digital word, so that the frequency synthesizer can be used to compensate for crystal frequency drift in the RF transceiver. Serial Interface The serial interface is a versatile three-wire interface consisting of three pins: Clock (serial clock), Data (serial input), and CS (chip select). It enables the SKY72300-21 to operate in a system where one or multiple masters and slaves are present. To perform a loopback test at startup and to check the integrity of the board and processor, the serial data is fed back to the master device (e.g., a microcontroller or microprocessor unit) through a programmable multiplexer. This facilitates hardware and software debugging. Registers There are ten 16-bit registers in the SKY72300-21. For more information, see the Register Descriptions section of this document. Main and Auxiliary '6 Modulators The fractionality of the SKY72300-21 is accomplished by the use of a proprietary, configurable 10-bit or 18-bit '6 modulator for the main synthesizer and 10-bit '6 modulator for the auxiliary synthesizer. Main and Auxiliary Fractional Units The SKY72300-21 provides fractionality through the use of main and auxiliary '6 modulators. The output from the modulators is combined with the main and auxiliary divider ratios through their respective fractional units. VCO Prescalers The VCO prescalers provide low-noise signal conditioning of the VCO signals. They translate from an off-chip, single-ended or differential signal to an on-chip differential Current Mode Logic (CML) signal. The SKY72300-21 has independent main and auxiliary VCO prescalers. Main and Auxiliary VCO Dividers The SKY72300-21 provides programmable dividers that control the CML prescalers and supply the required signals to the charge pump phase detectors. Programmable divide ratios ranging from 38 to 537 are possible in fractional-N mode and from 32 to 543 in integer-N mode. Reference Frequency Oscillator The SKY72300-21 has a self-contained, low-noise crystal oscillator. This crystal oscillator is followed by the clock generation circuitry that generates the required clock for the programmable reference frequency dividers. Reference Frequency Dividers The crystal oscillator signal can be divided by a ratio of 1 to 32 to create the reference frequencies for the phase detectors. The SKY72300-21 has both a main and an auxiliary frequency synthesizer, and provides independently configurable dividers of the crystal oscillator frequency for both the main and auxiliary phase detectors. The divide ratios are programmed by the Reference Frequency Dividers Register. NOTE: The divided crystal oscillator frequencies (which are the internal reference frequencies), Fref_main and Fref_aux, are referred to as reference frequencies throughout this document. Phase Detectors and Charge Pumps The SKY72300-21 uses a separate charge pump phase detector for each synthesizer which provides a programmable gain, Kd, from 31.25 to 1000 PA/2S radians in 32 steps programmed using the Phase Detector/Charge Pump Control Register. Frequency Steering When programmed for frequency power steering, the SKY72300- 21 has a circuit that helps the loop filter steer the VCO, through the LD/PSmain signal (pin 9). In this configuration, the LD/PSmain signal can provide for more rapid acquisition. When programmed for lock detection, internal frequency steering is implemented and provides frequency acquisition times comparable to conventional phase/frequency detectors. Lock Detection When programmed for lock detection, the SKY72300-21 provides an active low, pulsing open collector output using the LD/PSmain signal (pin 9) to indicate the out-of-lock condition. When locked, the LD/PSmain signal is tri-stated (high impedance). Power Down The SKY72300-21 supports a number of power-down modes through the serial interface. For more information, see the Register Descriptions section of this document.
DATA SHEET • SKY72300-21 FREQUENCY SYNTHESIZER 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 • Sep tember 11, 2009 5 Fractional-N Applications. The desired division ratio for the main and auxiliary synthesizers is given by: ref_div VCO fractional F FN where Nfractional must be between 37.5 and 537.5. The value to be programmed by the Main or Auxiliary Divider Register is given by: 32)N(RoundN fractionalreg NOTE: The Round function rounds the number to the nearest integer. When in fractional mode, allowed values for Nreg are from 6 to 505 inclusive. The value to be programmed by either of the MSB/LSB Dividend Registers or the Auxiliary Dividend Register is given by: )]32NN(divider[Rounddividend regfractional u where the divider is either 1024 in 10-bit mode or 262144 in 18-bit mode. Therefore, the dividend is a signed binary value either 10 or 18 bits long. NOTE: Because of the high fractionality of the SKY72300-21, there is no practical need for any integer relationship between the reference frequency and the channel spacing or desired VCO frequencies. Sample calculations for two fractional-N applications are provided in Figure 4. Integer-N Applications. The desired division ratio for the main or auxiliary synthesizer is given by: ref_div main_vco egerint F FN where Ninteger is an integer number from 32 to 543. The value to be programmed by the Main or Auxiliary Divider Register is given by: 32NN egerintreg When in integer mode, allowed values for Nreg are from 0 to 511 for both the main and auxiliary synthesizers. NOTE: As with all integer-N synthesizers, the minimum step size is related to the crystal frequency and reference frequency division ratio. A sample calculation for an integer-N application is provided in Figure 5. Register Loading Order. In applications where the main synthesizer is in 18-bit mode, the Main Dividend MSB Register holds the 10 MSBs of the dividend and the Main Dividend LSB Register holds the 8 LSBs of the dividend. The registers that control the main synthesizer’s divide ratio are to be loaded in the following order: xMain Divider Register xMain Dividend LSB Register xMain Dividend MSB Register (at which point the new divide ratio takes effect) In applications where the main synthesizer is in 10-bit mode, the Main Dividend MSB Register holds the 10 bits of the dividend. The registers that control the main synthesizer’s divide ratio are to be loaded in the following order: xMain Divider Register xMain Dividend MSB Register (at which point the new divide ratio takes effect) For the auxiliary synthesizer, the Auxiliary Dividend Register holds the 10 bits of the dividend. The registers that control the auxiliary synthesizer’s divide ratio are to be loaded in the following order: xAuxiliary Divider Register xAuxiliary Dividend Register (at which point the new divide ratio takes effect) NOTE: When in integer mode, the new divide ratios take effect as soon as the Main or Auxiliary Divider Register is loaded. Direct Digital Modulation The high fractionality and small step size of the SKY72300-21 allow the user to tune to practically any frequency in the VCO’s operating range. This allows direct digital modulation by programming the different desired frequencies at precise instants. Typically, the channel frequency is programmed by the Main Divider and MSB/LSB Dividend Registers, and the instantaneous frequency offset from the carrier is programmed by the Modulation Data Register. The Modulation Data Register can be accessed in three ways as defined in the following subsections.
- Main Divider Register = 0 0000 1101
- · Main Dividend Register, LSB = 1001 1000
- · Main Dividend Register, MSB = 00 0111 1101
- · The resulting main VCO frequency is 902.453 MHz
- · Step size is 76.3 Hz Note: The frequency step size for this case is 20 MHz divided by 218, giving 76.3 Hz. C1414
Figure 4. Fractional-N Applications: Sample Calculation (1 of 2)
where 11 0011 0100 is loaded in the MSB of the Main Dividend Register.
- Main Divider Register = 0 0001 0000
- · Main Dividend Register, MSB = 11 0011 0100
- · The resulting main VCO frequency is 917.775 MHz
- · Step size is 18.75 kHz Note: The frequency step size for this case is 19.2 MHz divided by 210, giving 18.75 kHz. C1415
Figure 4. Fractional-N Applications: Sample Calculation (2 of 2)
- · Auxiliary Divide Register = 0 0001 0010 C1416
Figure 5. Integer-N Applications: Sample Calculation Modulation Data Register with shortened CS strobes. selected through the Modulation Control Register. signal processor for modulation data). m multiplication of frequency deviation.
Table 1. SKY72300-21 Register Map
0 Main Divider Register 12 4
1 Main Dividend MSB Register 12 4
2 Main Dividend LSB Register 12 4
3 Auxiliary Divider Register 12 4
4 Auxiliary Dividend Register 12 4
5 Reference Frequency Dividers Register 12 4
6 Phase Detector/Charge Pump Control Register 12 4
7 Power Down/Multiplexer Output Se lect Control Register 12 4
8 Modulation Control Register 12 4
Note 1: All registers are write only. Note 2: No address bits are required for modulation data. Any serial data between 2 and 12 bits long is considered modulation data. range, the value of Ninteger must be changed. Dual Synthesizers/PLLs (document number 101349). and 0x3, which are set to 0x006. register are from 6 to 505 (fractional-N) or 0 to 511 (integer-N). of the 18-bit dividend for the main synthesizer. of the 18-bit dividend for the main synthesizer.
Figure 13. Power Down and Multiplexer Output Register (Write Only) Table 4. Multiplexer Output with a fractionality of 218 and a step size of Fref_main/262144. fractionality of 210 and a step size of Fref_main/1024. synthesizer is in power-down mode. set, the auxiliary synthesizer is in integer-N mode. Refer to Table 4 for more information. enabled. When this bit is set, the Mux_out pin is tri-stated.
Application Note, Tape and Reel, document number 101568. pad should be soldered directly to the circuit board. specifications are provided in Table 8. Figure 16 provides a schematic diagram for the SKY72300-21. EP-TSSOP and Figure 18 provides the tape and reel dimensions. Table 5. SKY72300-21 Signal Descriptions (1 of 2) Data pin on the rising edge of Clock. 2 Mod_in Digital input Alternate serial modulation data input pin. Address bits are followed by data bits. the general synthesizer registers. 4 VSUBdigital – Substrate isolation. Connect to ground. 5 GNDecl/cml (Note 1) Power and ground Emitte r Coupled Logic (ECL)/Current Mode Logic (CML) ground.
6 VCCcml_main
Power and ground ECL/CML 3 V. Removing power safely powers down the associated divider chain and charge pump. 7 Fvco_main Input Main VCO differential input. 8 Fvco_main Input Main VCO compliment ary differential input. pin is configured using the Phase Detector/Charge Pump Control Register.
10 VCCcp_main
Detector/Charge Pump Control Register.
12 GNDcp_main
Power and ground Main charge pump ground. 13 Xtalacgnd/OSC Ground/input Reference crystal AC ground or external oscillator differential input. 14 Xtalin/OSC Input Reference crystal input or external oscillator differential input. 15 Xtalout/NC Input Reference cr ystal output or no connect. 16 VCCxtal Power and ground Crystal oscillator ECL/CML, 3 V. 17 GNDxtal Power and ground Crystal oscillator ground. collector output (high impedance when lock is detected), or helps the loop filter steer the auxiliary VCO. This pin is configured using the Phase Detector/Charge Pump Control Register.
Table 5. SKY72300-21 Signal Descriptions (2 of 2) Phase Detector/Charge Pump Control Register. 21 GNDcp_aux (Note 1) Power and ground Auxiliary charge pump ground. 22 Fvco_aux Input Auxiliary VCO complimentary differential input. 23 Fvco_aux Input Auxiliary VCO differential input.
24 VCCcml_aux
Power and ground ECL/CML, 3 V. Removing power safely powers down the associated divider chain and charge pump. 25 GNDdigital (Note 1) Power and ground Digital ground. 26 VCCdigital (Note 1) Power and ground Digital 3 V. 27 Data Digital input Serial address and data input pin. Address bits are followed by data bits. 28 CS Digital input Active low enable pin. Enables loading of address and data on the Data pin on the rising edge of Clock. Note 1: Associated pairs of power and ground pins must be decoupled using 0.1 PF capacitors. Table 6. Absolute Maximum Ratings parameters set at or below their nominal values. Exceeding any of the limits listed here may result in permanent damage to the device. or equipment, which can discharge without detection. Industry-standard ESD precautions should be used at all times. Table 7. Recommended Operating Conditions Note 1: When power steering is enabled, the charge pump must be 4.5 V maximum.
Table 8. Electrical Characteristics (Note 1) (1 of 2)
Table 8. Electrical Characteristics (Note 1) (2 of 2) temperatures may reduce reliability of the device. Note 2: A 5 V charge pump power supply (on pin 10 and/or pin 19) results in higher power-down leakage current. Note 3: The minimum synthesizer frequency is 12 x FOSC, where FOSC is the frequency at the Xtalin/OSC pin.
Figure 16. SKY72300-21 Application Schematic
1.1 Max
Figure 17. SKY72300-21 28-Pin EP-TSSOP Package Dimensions
- Carrier tape material: black conductive polystyrene
- Cover tape material: transparent conductive PSA
- Cover tape size: 13.3 mm width
- All measurements are in millimeters C1430
Figure 18. SKY72300-21 Tape and Reel Dimensions
DATA SHEET • SKY72300-21 FREQUENCY SYNTHESIZER Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 22 September 11, 2009 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Not ice • 101217N
Ordering Information
Model Name Manufacturing Part Number Evaluation Kit Part Number SKY72300-21 2.1 GHz Frequency Synthesizer SKY72300-21 (Pb-free package) Tw16-D400-011 Copyright © 2001, 2002, 2004, 2005, 2006, 2007, 2009 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.
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