3239-11 Просмотр технического описания (PDF) - Peregrine Semiconductor
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3239-11 Datasheet PDF : 12 Pages
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PE3239
Product Specification
Enhancement Register
The functions of the enhancement register bits are shown below with all bits active “high”.
Table 9. Enhancement Register Bit Functionality
Bit Function
Bit 0
Reserved**
Bit 1
Reserved**
Bit 2
fp output
Bit 3
Power down
Bit 4
Counter load
Bit 5
MSEL output
Bit 6
fc output
Bit 7
Reserved**
Description
Drives the M counter output onto the Dout output.
Power down of all functions except programming interface.
Immediate and continuous load of counter programming.
Drives the internal dual modulus prescaler modulus select (MSEL) onto the Dout output.
Drives the reference counter output onto the Dout output
** Program to 0
Phase Detector
The phase detector is triggered by rising edges
from the main Counter (fp) and the reference
counter (fc). It has two outputs, namely PD_U,
and PD_D. If the divided VCO leads the divided
reference in phase or frequency (fp leads fc),
PD_D pulses “low”. If the divided reference leads
the divided VCO in phase or frequency (fc leads
fp), PD_U pulses “low”. The width of either pulse
is directly proportional to phase offset between the
two input signals, fp and fc.
The signals from the phase detector couple
directly to a charge pump. PD_U controls a
current source at pin CP with constant amplitude
and pulse duration approximately the same as
PD_U. PD_D similarly drives a current sink at pin
CP. The current pulses from pin CP are low pass
filtered externally and then connected to the VCO
tune voltage. PD_U pulses result in a current
source, which increases the VCO frequency and
PD_D results in a current sink, which decreases
VCO frequency when using a positive Kv VCO.
A lock detect output, LD is also provided, via the
pin Cext. Cext is the logical “NAND” of PD_U and
PD_D waveforms, which is driven through a series
2 kohm resistor. Connecting Cext to an external
shunt capacitor provides low pass filtering of this
signal. Cext also drives the input of an internal
inverting comparator with an open drain output.
Thus LD is an “AND” function of PD_U and PD_D.
Figure 8. Typical PE3239 Loop Filter Application Example
Charge
Pump
To VCO
Tune
R
C2
C1
©2006 Peregrine Semiconductor Corp. All rights reserved.
Page 10 of 12
Document No. 70-0047-02 │ UltraCMOS™ RFIC Solutions
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