Product Specification
PE3341
Page 6 of 17
©2005-8 Peregrine Semiconductor Corp. All rights reserved. Document No. 70-0053-05 │UltraCMOS™ RFIC Solutions
Functional Description
The PE 33 41 c o ns is ts of a du al mo dul us pr es caler,
three programmable counters, a phase detector
with charge pump and control logic with EEPROM
memory (see Figure 1).
The dual modulus prescaler divides the VCO
frequency by either 10 or 11, depending on the
state of th e internal modulus select logic. The R
and M counters divide the reference and prescaler
outputs by integer values stored in one of three
selectable registers. The modulu s sele ct logic
uses th e 4- bi t A coun ter .
The ph as e- freque nc y detector generat es up and
down frequency control signals that direct the
char g e pump o peratio n, an d ar e als o us e d to
enable a lock detect circuit.
Frequency control data is loaded into the device
via the Serial Data Port, and can be placed in
three separate frequency registers. One of these
registers (EE register) is used to load from and
write to the non-volatile 20-bit EEPROM.
Various operational and test modes are available
through the enhancement register, which is only
accessible through the Serial Data Port (it cannot
be lo aded from the EEPROM).
Main Counter Chain
The main counter chain divides the RF input
frequency, Fin, by an integer derived from the
user-defined values in the M and A counters. It
operates in two modes:
High Frequency Mode
Setting PB (prescaler bypass) LOW enables the
÷10 /1 1 pr esc aler, pr ovi di n g op er ation to 2.7 GHz .
In this mode, the output from the main counter
chain, fp, is related to the VCO frequency, Fin, by
the following equation:
fp = Fin / [10 x (M + 1) + A] (1)
wh ere 0
≤
A
≤
15 and A
≤
M + 1; 1
≤
M
≤
511
When the loop is lo cked, Fin is related to the
reference freque nc y, fr, by the fo llowing equation:
Fin = [10 x (M + 1) + A] x (fr / (R+1)) (2)
wh ere 0
≤
A
≤
15 and A
≤
M + 1; 1
≤
M
≤
511
A consequence of the uppe r lim it on A is th at F in
must be greater than or equ al to 90 x (fr / (R+1)) to
obtain contiguous channels. Programming the M
counter with the min imum value of 1 will result in a
minimum M counter divide ra tio of 2.
Programming the M and A counters with their
maximum values provides a divide ratio of 5135.
Prescaler Bypass Mode
Setti ng the PB bi t of a fr eq ue ncy re gis ter HIGH
allo ws F in to bypass the ÷10/11 prescaler. In this
mode , t he pr escaler an d A co un ter ar e powered
down, and the input VCO frequency is divided by
the M counter directly. The following equation
relate s Fin to the reference freque ncy fr:
Fin = (M + 1) x (fr / (R+1)) (3)
wh ere 1 ≤ M ≤ 511
Refe rence Counter
The reference counter chain divides the reference
freq ue nc y, fr, down to the phase detector
compar i son freq ue nc y, fc.
The output frequency of the 6-bit R Counter is
related to the reference frequency by the follo wing
equation:
fc = fr / (R + 1) (4)
where 0
≤
R
≤
63
Not e that programming R with 0 will pass the
reference freque nc y, fr, directly to the phase
detecto r.
Phase Detector and Charge Pump
The phase detector is triggered by rising edges
from the main co unter (fp) and the re fe rence
co unte r (fc). It has two outputs, PD_U, and PD_D.
If the divided VCO leads the divided reference in
phase or frequency (fp leads fc), PD_D p ul s es
LOW. If the divided reference leads the divided
VCO in phase or freq uency (fc leads fp), PD_U
pulses LOW. The width of either pulse is directly
prop or ti o nal to th e phas e offset betw e en th e fp an d
fc signals.
The signals from the phase detector are also
routed to an internal charge pump. PD_U controls
a current source at pin CP, and PD_D controls a
curr ent sink at pin CP. Whe n usi n g a posi ti ve Kv
VCO, PD_U pulses (current source) will increase
the VCO f requency, and PD_D pulses ( current
sink) will decrease VCO frequency.
Peregrine products are protected under one or more of the following U.S. Patents: http://patents.psemi.com