DATA SHEET • SKY74038 FREQUENCY SYNTHESIZER
Table 5. SKY74038 Register Descriptions (1 of 2)
Symbol
Register Word Address 00b
Address bits [1:0]
SC2
IF synthesizer charge-pump output current
[3:2]
00b
Bits [3:2] select the IF synthesizer charge pump output current:
bit 3
0
0
1
1
LD
Test mode [6:4]
bit 2
0
1
0
1
Select 0.4 mA charge pump output current
Select 0.8 mA charge pump output current
Select 1.2 mA charge pump output current
Select 1.6 mA charge pump output current
Function
Description
Bits [6:4] set the test mode:
bit 6
0
0
0
0
1
1
1
1
bit 5 bit 4
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Multiplex Ndiv output of IF SX to LD output
Multiplex Rdiv output of IF SX to LD output
Multiplex lock detect output of IF SX to LD output
Multiplex ANDed lock detect of both SX to LD output
Multiplex Ndiv output of RF SX to LD output
Multiplex Rdiv output of RF SX to LD output
Multiplex lock detect output of RF SX to LD output
Hi-Z the charge pump output of RF SX
R2
IF synthesizer reference divider [19:7]
RF synthesizer fractional-N mode selection
[21:20] (Note 1)
Bits [19:7] set the IF synthesizer 13-bit reference divider ratio
Bits [21:20] set the RF synthesizer fractional-N mode:
bit 21 bit 20
0
0
1
1
0
1
0
1
Reserved
Reserved
Fractional-N mode with dithering
Fractional-N mode without dithering
Register Word Address 01b
Address bits [1:0]
SP1
RF synthesizer phase detector output
polarity [2]
01b
Bit [2] sets the polarity of the RF synthesizer phase detector output:
0 = Set phase detector output for negative VCO gain
1 = Set phase detector output for positive VCO gain
Bits [4:3] set the RF synthesizer charge pump output current:
bit 4
0
0
1
1
PS
RF synthesizer prescaler selection [5]
bit 3
0
1
0
1
Select 120
µA
charge pump output current
Select 240
µA
charge pump output current
Select 360
µA
charge pump output current
Select 480
µA
charge pump output current
SC1
RF synthesizer charge-pump output current
[4:3]
Bit [5] selects the RF synthesizer prescaler:
0 = Select 8/9 prescaler
1 = Select 16/17 prescaler
R1
ME
RF synthesizer reference divider [8:6]
RF synthesizer modulo extender [21:9]
Bits [8:6] set the RF synthesizer’s three-bit reference divider ratio
Bits [21:9] extend the RF synthesizer’s fractional modulo up to 2,097,152 (optional)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
101075M • Skyworks Proprietary and Confidential information • Products and Product Information are Subject to Change Without Notice • June 4, 2007
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