S1M8837 Просмотр технического описания (PDF) - Samsung
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S1M8837 Datasheet PDF : 29 Pages
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FRACTIONAL-N RF/INTEGER-N IF DUAL PLL
FUNCTIONAL DESCRIPTION
S1M8836/37
finRF
+
finRF
-
CLOCK
DATA
LE
RF
Prescaler
RF
N Counter
∑ -∆
Modulator
Serial Data Control
RF
R Counter
OSC in
finIF
+
finIF
-
IF
R Counter
IF
Prescaler
IF
N Counter
RF
Phase
Detector
RF
Charge
Pump
RF
LD
CMOS
Output
MUX
foLD
Data Out
Multiplexer
CMOS
Output
MUX
IF
LD
IF
Phase
Detector
IF
Charge
Pump
CP oRF
OUT0
foLD
OUT1
CP oIF
The Samsung S1M8836/37 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. S1M8836/37 combined with an external LPF and
an external VCO 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 prescaler amplifies the RF input power of -10dBm from the external RF/IF VCO to the
sufficient ECL switching level to drive the following ECL divider so that it can be normally operated 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. 8/9/12/13 for S1M8836, div. 16/17/20/21 for S1M8837, div. 8/9 for IF), the N counter
and the Fractional-N circuitry( Σ - ∆ modulator). External reference signal is divided by the R counter to set the
comparison frequency 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.
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