CX74038 SKYWORKS | Alldatasheet

Document overview

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Technical content

Features

  • Maximum operating frequency: 2.6 GHz
  • Maximum IF synthesizer frequency: 800 MHz
  • Supply voltage as low as 2.6 V
  • Fast frequency settling time with fractional-N operation
  • Internal fractional spur reduction
  • Programmable charge pump currents
  • Digital lock detector
  • Power saving at lower frequency
  • TSSOP (20-pin, 6.5 x 4.4 x 1.0 mm) package

Description

The Skyworks CX74038 is a complete, low-power 2.6 GHz/800 MHz dual frequency synthesizer. The device provides both Radio Frequency (RF) channels and Intermediate Frequency (IF) channels. Fractional-N operation offers low phase noise, fast settling time, and low spurious tones for RF channels. A standard integer-N division is used for IF channels. The three-wire serial interface provides programmable control of the frequency synthesizer to support dual-conversion transceivers. The 20-pin Thin Shrink Small Outline Package (TSSOP) device package and pin configuration are shown in Figure 1. A functional block diagram of the CX74038 is shown in Figure 2. VDD1_RF VDD2_RF CPO_RF GND GND FREF GND LD_TP VDD1_IF VDD2_IF CPO_IF C1452 GND IFIN IFINB GND LE DAT CLK RFIN RFINB Figure 1. CX74038 Pinout – 20-Pin TSSOP

Figure 2. CX74038 Frequency Synthesizer Block Diagram frequency drift in the RF transceiver. go high, the data does not get transferred to the register. pulsed to make the transfer to the specific device register. Data/address transfer is MSB first.

DATA SHEET • CX74038 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 4 January 31, 2005 • Skyworks Proprietary a nd Confidential information • Products and product information are subject to change without notice • 101075I can have a programmable charge pump current from 0.4 mA to 1.6 mA and 120 µA to 480 µA, respectively. For optimum performance, the divided reference frequency presented at the phase detector input must not exceed 9 MHz using the RF 16/17 prescaler synthesizer mode, 15 MHz using the RF 8/9 prescaler, or 2 MHz for the IF synthesizer mode. The comparison frequency is also limited by the desired frequency divided by the minimum divide ratio. The charge-pump can be programmed to high impedance (Hi-Z) state for open-loop VCO modulation use. Lock Detection The output of the IF/RF dividers (R1, N1, R2, N2) and lock detectors for both synthesizers can be multiplexed to the LD pin. When programmed for lock detection, the CX74038 provides an active low output to indicate the out-of-lock condition. When locked, the LD pin is high. Power Down The CX74038 supports a number of power-down modes through the serial interface. Both IF and RF synthesizer blocks can be powered down, powered up individually, or both powered up using the EN bits (see the Synthesizer Register Programming section of this document). The CX74038 is enabled at power up by default. Synthesizer Register Programming IF Integer-N Synthesizer. The N2 17-bit divider ratio is calculated using the following equation: IF N2 FREF As with all integer-N synthesizers, the minimum step size is related to the divided reference frequency, FREF. RF Fractional-N Synthesizer. The N1 divider ratio is calculated using the following equation: RF FREF where: N1Total = N1 + 3.5 + FN + ME FN sets the fractional-N modulo up to 256 modulo, as calculated by: FN D 9 2--- D8 22----- D7 23----- ... + D2 28----- +++= where: Dn represents the bit locations within the register field. The fractional modulo can be extended up to 221 using the modulo extender (ME), if required, as shown by the following equation: ME D 21 29----- D20 D19 ... +++ D9 Because the way the ∆Σ modulator is implemented in the CX74038, the number 3.5 must be added to the division number to obtain the final division ratio. If the integer field of the N divider shows a non-integer number, the desired frequency or the division fraction portion needs to be adjusted. Sample calculations for two fractional-N applications are shown in Figure 5. Electrical and Mechanical Specifications Signal pin assignments and functional pin descriptions are specified in Table 1. The absolute maximum ratings of the CX74038 are provided in Table 2. The recommended operating conditions are specified in Table 3 and electrical characteristics are provided in Table 4. Table 5 provides the register descriptions. Package dimensions for the CX74038 are shown in Figure 6 and tape and reel dimensions for the 20-pin TSSOP package are shown in Figure 7. Electrostatic Discharge Information The CX74038 is an electrostatic sensitive device. Observe precautions when handling.

8 MHz

In this example, N1 is greater than 256, the minimum divide ratio for the 16/17 prescaler. Figure 5. Fractional-N Applications: Sample Calculation (1 of 2)

13 MHz

In this example, N1 is greater than 64, the minimum divide ratio for the 8/9 prescaler. Figure 5. Fractional-N Applications: Sample Calculation (2 of 2)

Table 1. CX74038 Signal Descriptions

1 VDD1_RF — Power supply for RF digital circuits 11 CLK I Serial interface clock input

2 VDD2_RF — Power supply for RF analog circuits 12 DAT I Serial interface data input

3 CPO_RF O RF charge pump output 13 LE I Serial interface Latch Enable input

4 GND — Ground 14 GND — Ground

5 RFIN I RF prescaler input 15 IFINB I IF prescaler complementary input

6 RFINB I RF prescaler complementary input 16 IFIN I IF prescaler input

7 GND — Ground 17 GND — Ground

8 FREF I Reference divider input 18 CPO_IF O IF charge pump output

9 GND — Ground 19 VDD2_IF — Power supply for IF analog circuits

10 LD_TP O Multiplexed out put from lock detectors

20 VDD1_IF — Power supply for IF digital circuits

Table 2. Absolute Maximum Ratings parameters set at or below their nominal values. Table 3. Recommended Operating Conditions

Table 4. Electrical Characteristics Note 1: RF output frequency = 2.5 GHz, comparison frequency = 8 MHz, loop bandwidth = 35 kHz, and charge pump current = 480 mA. IF output frequency = 480 MHz, comparis on frequency = 200 kHz, loop bandwidth = 10 kHz, and charge pump current = 1.6 mA.

Table 5. CX74038 Register Descriptions (1 of 2)

0 Sets phase detector output for negative VCO gain

1 Sets phase detector output for positive VCO gain

0 Select 8/9 prescaler

1 Select 16/17 prescaler

Table 5. CX74038 Register Descriptions (2 of 2) Note 1: These bits must be programmed after power is applied to the device. Failure to do so may result in erroneous device operation.

DATA SHEET • CX74038 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 12 January 31, 2005 • Skyworks Proprietary a nd Confidential information • Products and product information are subject to change without notice • 101075I

Ordering Information

Model Name Manufacturing Part Numb er Evaluation Kit Part Number CX74038 2.6 GHz/800 MHz Frequency Synthesizer CX74038-12 PH00-D222 Copyright © 2002, 2003, 2004, 2005 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products. These materials 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. Skyworks may make changes to its documentation, products, specifications and product descriptions at any time, without notice. Skyworks makes no commitment to update the information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from future changes to its documentation, products, specifications and product descriptions. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by or under this document. Except as may be provided in Skyworks’ Terms and Conditions of Sale for such products, Skyworks assumes no liability whatsoever in association with its documentation, products, specifications and product descriptions. THESE MATERIALS ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED OR OTHERWISE, RELATING TO SALE AND/OR USE OF SKYWORKS PRODUCTS INCLUDING WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. SKYWORKS FURTHER 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 SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THESE MATERIALS 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. 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. The following are trademarks of Skyworks Solutions, Inc.: Skyworks®, the Skyworks logo, and Breakthrough Simplicity®. Product names or services listed in this publication are for identification purposes only, and may be trademarks of Skyworks or other third parties. Third-party brands and names are the property of their respective owners. Additional information, posted at www.skyworksinc.com, is incorporated by reference.