SKY72300-21 Datasheet, PDF (2/23 Pages) Skyworks Solutions Inc. – SKY72300-21: Spur-Free, 2.1 GHz Dual Fractional-N Frequency Synthesizer

DATA SHEET • SKY72300-21 FREQUENCY SYNTHESIZER
The SKY72300-21 has a frequency power steering circuit that
helps the loop filter to steer the VCO when the frequency is too
fast or too slow, further enhancing acquisition time.
The unit operates with a three-wire, high-speed serial interface. A
combination of large bandwidth, fine resolution, and the three-
wire, high-speed serial interface allows for a direct frequency
modulation of the VCO. This supports any continuous phase,
constant envelope modulation scheme such as Frequency
Modulation (FM), Frequency Shift Keying (FSK), Minimum Shift
Keying (MSK), or Gaussian Minimum Shift Keying (GMSK).
This capability can eliminate the need for In-phase and
Quadrature (I/Q) Digital-to-Analog Converters (DACs), quadrature
upconverters, and IF filters from the transmitter portion of the
radio system.
Figure 1 shows a functional block diagram for the SKY72300-21.
The device package and pinout for the 28-pin Exposed Pad Thin
Shrink Small Outline Package (EP-TSSOP) are shown in Figure 2.
Data
Registers
Clock
CS
Serial
Interface
Modulation
Data
Main
MSB/LSB
Dividend
Main Modulation Ref Freq
Divider Control Dividers
Aux
Divider
PD/Charge Pump
& Pwr-Dn/Mux Out
Control
Aux
Dividend
Mod_in
Modulation
Unit
Mux
Mux_out
ΔΣ
18-Bit
ΔΣ
10-Bit
Fvco_main
Fvco_main
Main
Divider
Fractional
Unit
Reference
Frequency
Oscillator
Fractional
Unit
Main
Divider
Auxiliary
Divider
Fpd_main
Fref_main
Fref_aux
Fpd_aux
Main
Phase/Freq.
Detector
and
Charge Pump
Fref
Reference
Frequency
Oscillator
Auxiliary
Phase/Freq.
Detector
and
Charge Pump
Auxiliary
Prescaler
Fvco_aux
Fvco_aux
Lock Detection or
Power Steering
CPout_main
LD/PSmain
CPout_aux
LD/PSaux
Lock Detection or
Power Steering
C1447
Figure 1. SKY72300-21 Functional Block Diagram
Clock 1
Mod_in 2
Mux_out 3
VSUBdigital 4
GNDcml 5
VCCcml_main 6
Fvco_main 7
Fvco_main 8
LD/PSmain 9
VCCcp_main 10
CPout_main ¹¹
GNDcp_main 12
Xtalacgnd/OSC 13
Xtalin/OSC 14
28
CS
27
Data
26
VCCdigital
25
GNDdigital
24
VCCcml_aux
23
VCCvco_aux
22
Fvco_aux
21
GNDcp_aux
20
CPout_aux
19
VCCcp_aux
18
LD/PSaux
17
GNDxtal
16
VCCxtal
15
Xtalout/NC
C1412
Figure 2. SKY72300-21 Pinout, 28-Pin EP-TSSOP
(Top View)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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September 11, 2009 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 101217N