SKY72300-21 Skyworks Solutions Inc, SKY72300-21 Datasheet - Page 6

• Manufacturer Part Number: SKY72300-21
• Description: IC SYNTHESIZER 2.1GHZ 28-EPTSSOP
• Manufacturer: Skyworks Solutions Inc
• Type: Fractional N Synthesizerr

Specifications of SKY72300-21

• Pll: Yes
• Input: Clock, Crystal
• Output: Clock, Crystal
• Number Of Circuits: 1
• Ratio - Input:output: 2:2
• Differential - Input:output: Yes/Yes
• Frequency - Max: 2.1GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 2.7 V ~ 3.3 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• Frequency-max: 2.1GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 863-1076-2

DATA SHEET • SKY72300-21 FREQUENCY SYNTHESIZER
6
Case 1: To achieve a desired F
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
September 11, 2009 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 101217N
of the synthesizer in 18-bit mode. Since the maximum internal reference frequency (F
frequency is divided by 2 to obtain a F
The value to be programmed in the Main Divider Register is:
With the modulator in 18-bit mode, the value to be programmed in the Main Dividend Registers is:
where 00 0111 1101 is loaded in the MSB of the Main Dividend Register and 1001 1000 is loaded in the LSB of the
Main Dividend Register.
Summary:
· · 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 2
N
N
dividend = Round[divider × (N
fractional
reg
= Round[N
= Round[45.12265] – 32
= 45 – 32
= 13 (decimal)
= 000001101 (binary)
= Round[262144 × (45.12265 – 13 – 32)]
= Round[262144 × (0.12265)]
= Round[32151.9616]
= 32152 (decimal)
= 000111110110011000 (binary)
= F
= 902.4530
= 45.12265
Figure 4. Fractional-N Applications: Sample Calculation (1 of 2)
vco_main
F
vco_main
fractional
div_ref
20
frequency of 902.4530 MHz using a crystal frequency of 40 MHz with operation
] – 32
fractional
div_ref
of 20 MHz. Therefore:
– N
reg
– 32)]
18
, giving 76.3 Hz.
div_ref
) is 25 MHz, the crystal
C1414