sky73112-11 Skyworks Solutions, Inc., sky73112-11 Datasheet - Page 9

• Manufacturer Part Number: sky73112-11
• Description: Sky73112-11 750-850 Mhz High Performance Vco/synthesizer With Integrated Switch
• Manufacturer: Skyworks Solutions, Inc.

VCO Prescalers
The VCO prescalers divide the VCO output signal by either 16/17
or 8/9. The
17 in the 16/17 mode, or whether to divide by 8 or 9 in the 8/9
mode. The 8/9 mode provides the best performance for the
SKY73112-11.
N-Counter
The N-counter consists of two asynchronous ripple counters, a
6-bit M-counter and a 4-bit A-counter. The M-counter determines
the counts using the lower division ratio in the prescaler (8 or 16);
the A-counter determines the counts using the upper division ratio
(9 or 17).
The total N-counter divider ratio for the 8/9 mode is 56 (8 × 7)
minimum; for the 16/17 mode, the ratio is 240 (16 × 15)
minimum.
DATA
CLK
LD
LE
D25
D24
modulator determines whether to divide by 16 or
Word 0
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
200736B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • November 30, 2009
D1
866
864
862
860
858
856
854
852
850
848
846
844
842
840
838
836
834
832
830
D0
0
D25
50
Word 1 (Bit [20] low)
Digital Tune
(VCO Auto-Tuning)
D24
Figure 7. VCO Auto-Tuning @ 850 MHz Frequency Settling
D1
100
D0
150
Figure 6. POR Timing Diagram
Analog Tune
D25
D24
200
Word 2
D1
Time (μs)
D0
250
By changing the counter setting at each reference clock cycle, the
Modulated Fractional Divider (MFD) achieves the desired noise
shaping.
VCO MFD Block
The MFD block divides down the prescaler output to the Phase
Locked Loop (PLL) reference frequency. A third order cascaded
of the division ratio.
The MFD block controls the division ratio by dynamically
programming the M and A counters in the N-counter.
Phase Detector and Charge Pump
The phase detector and charge pump detect and integrate the
phase and frequency errors of the divided down VCO output
versus the reference clock. This results in a feedback adjustment
of the control voltage for the VCO.
modulation technique minimizes spurs through randomization
D25
300
D24
Word 3
D1
350
DATA SHEET • SKY73112-11 VCO/SYNTHESIZER
D0
400
D25
Word 1 (Bit [20] high)
D24
450
D1
S1578
D0
500
Phase Settling Time
S1296
9