S1M8831A Samsung Semiconductor, Inc., S1M8831A Datasheet - Page 12

• Manufacturer Part Number: S1M8831A
• Description: Fractional-n Rf/integer-n If Dual Pll Frequency Synthesizer
• Manufacturer: Samsung Semiconductor, Inc.

S1M8831A/33
FUNCTIONAL DESCRIPTION
The Samsung S1M8831A/33 is RF/IF dual frequency synthesizer IC which supports Fractional-N mode for RF
PLL and Integer-N mode for IF PLL depending on a program control. S1M8831A/33 combined with external
LPFs and external VCOs forms PLL frequency synthesizer. The frequency synthesizer consists of prescalers,
pulse-swallowed programmable N counters, programmable reference R counters, phase detectors,
programmable charge pumps, analog LD (Lock Detector), serial data control, etc.
An input buffer in the prescalers amplifies an RF input power of -10dBm from external RF/IF VCOs to a
sufficient ECL switching level to drive the following ECL divider so that it can normally operate even in a smaller
input power less than -10dBm. The amplified VCO output signal is divided by the prescaler with a pre-determined
divide ratio (div. 8/9 in S1M8831A, div. 16/17 in S1M8833, div. 8/9 in IF), the N counter, or the Fractional-N
circuitry (
of the PFD. The divide ratios of the programmable counters can be programmed via the serial bus interface.
These two signals drive the both inputs of the phase detector. The phase detector drives the charge pump by
comparing frequencies and phases of the above two signals. The charge pump and the external LPF make the
control voltage for the external VCO and finally the VCO generates the appropriate frequency signal.
12
CLOCK
OSCx
OSC
DATA
f
f
f
f
in
in
in
in
RF
RF
IF
IF
in
LE
-
modulator). External reference signal is divided by the R counter to set the comparison frequency
+
+
-
-
Prescaler
Prescaler
RF
Serial Data Control
IF
R Counter
R Counter
RF
IF
N Counter
Modulator
N Counter
RF
-
IF
FRACTIONAL-N RF/INTEGER-N IF DUAL PLL
Detector
Phase
IF
Detector
Phase
RF
Multiplexer
Data Out
f
o
LD
LD
IF
RF
LD
Charge
Charge
Output
CMOS
CMOS
Output
Pump
Pump
MUX
MUX
RF
IF
OUT0
OUT1
CP
CP
f
o
LD
o
o
RF
IF