Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

NJ88C50NP Datasheet(PDF) 5 Page - Zarlink Semiconductor Inc

Part # NJ88C50NP
Description  Dual Low Power Frequency Synthesiser
Download  17 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  ZARLINK [Zarlink Semiconductor Inc]
Direct Link  http://www.zarlink.com
Logo ZARLINK - Zarlink Semiconductor Inc

NJ88C50NP Datasheet(HTML) 5 Page - Zarlink Semiconductor Inc

  NJ88C50NP Datasheet HTML 1Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 2Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 3Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 4Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 5Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 6Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 7Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 8Page - Zarlink Semiconductor Inc NJ88C50NP Datasheet HTML 9Page - Zarlink Semiconductor Inc Next Button
Zoom Inzoom in Zoom Outzoom out
 5 / 17 page
background image
5
NJ88C50
The normal value of Iprop, Iprop(0), is obtained while the
strobe line of the serial programming bus is held low. In this
condition, the second charge pump providing the integral
feedback term is inactive.
Speed up Mode
In speed up mode the loop bandwith during switching
is increased to allow faster initial frequency acquisition. This
is done by using the dual phase detector outputs (PDP and
PDI) connected to a standard passive loop filter as shown in
fig.5. The effect of this is to increase the loop gain and hence
the bandwidth while maintaining a constant phase margin
when switching between speed up mode and normal mode.
The synthesiser operates in speed up mode when the
strobe line goes high loading either word A or word A2 (see
programming section Page 8-Page 9) and it will stay in this
mode until the strobe line goes low. In this mode the following
current levels are produced. The charge pump providing the
proportional feedback will increase its current from Iprop(0) to
a value Iprop(1), where
Iprop(1) = 2L+1 .Iprop(0)
where L is a two bit number loaded as part of the serial
programming data. Iprop(1) will therefore be 2, 4, 8 or 16
times Iprop(0). The charge pump supplying Iprop is specified
up to a value of 1mA.
Also when the strobe line goes high loading word A or
word A2, the charge pump providing the integral feedback
term becomes active at a current level Iint given by
Iint = K.Iprop(1)
where K is a four bit number loaded as part of the serial
programming data. Although Iint can be programmed to be
240 times greater than Iprop(0), the charge pump supplying
Iint is only specified up to a value of 10mA.
For all charge pumps, a pull-up current indicates the VCO
frequency should be increased while a pull-down current
indicates the VCO frequency should be decreased.
For the proportional and integral charge pumps, the
selected pulse current levels will remain substantially
constant over the charge pumps output voltage ranges
tabulated in the electric characteristics. “Substantially
constant” means that the current will not have changed by
more than 10% of the value measured at 2.5 volts on the
output .
FRACTIONAL-N OPERATION
Conventional, non fractional-N synthesisers have a
frequency resolution or step size equal to the phase detector
comparison frequency. Fractional-N refers to a technique
which allows finer frequency steps to be obtained.
The synthesised frequency with a conventional
synthesiser is equal to N times the phase detector comparison
frequency, where N is the programmable integer loop divide
ratio. Using fractional-N the value of N is alternated between
N and N+1 in order to simulate a fractional part. For example
9000.375 would be simulated by alternating between 9000
and 9001 in the pattern
9000, 9000, 9001, 9000, 9000, 9001, 9000, 9001 (mean value of 9000.375).
On the NJ88C50 the fractional-N circuit consists of an
accumulator which can be set to overflow at a value of 5 or 8
(FMOD in programming word D, see page 9). The value in the
accumulator, A, is incremented once every comparison cycle
of the main phase detector and every time the accumulator
overflows the total division ratio of the synthesiser and
prescaler is increased from N to N+1. To obtain the pattern
described above N=9000 and FMOD would be set to mod8
and the incremental value, NF(programmed in word A) would
be set to 3. The accumulator would then behave as shown
below.
Increment
Accumulator
Total Division
Value
Value
Ratio
3
3
9000
3
6
9000
3
1
9001
3
4
9000
3
7
9000
3
2
9001
3
5
9000
3
0
9001
Varying NF allows different fractions to be obtained. If NF=1
and FMOD=8 the accumulator would overflow once in every
8 cycles giving a value of 9000.125. Similarly if NF=4 the
accumulator overflows every other cycle giving 9000.5.
For a given step size this increase in resolution means a higher
comparison frequency at the phase detector, and therefore a
lower overall division ratio. For example,
with a
step size = 200kHz
and
carrier frequency = 900MHz
Non fractional-N synthesiser
Comparison frequency=200kHz
Division ratio=900MHz=4500
200kHz
Fractional-N synthesiser (using 5ths)
Comparison frequency=1MHz
Division ratio=900MHz=900
1MHz
In most applications the phase noise is proportional to the
overall division ratio. Therefore fractional-N gives lower phase
noise. This higher comparison frequency and lower phase
noise allows circuits to be built with wider loop bandwidths
while keeping the same stability. This means that phase
locked loops (PLLs) can be made to either switch faster for a
given phase noise or be quieter for a given switching speed,
compared to conventional designs.


Similar Part No. - NJ88C50NP

ManufacturerPart #DatasheetDescription
logo
Mitel Networks Corporat...
NJ88C50NPAS MITEL-NJ88C50NPAS Datasheet
209Kb / 15P
   Dual Low Power Frequency Synthesiser
More results

Similar Description - NJ88C50NP

ManufacturerPart #DatasheetDescription
logo
Mitel Networks Corporat...
NJ88C50 MITEL-NJ88C50 Datasheet
209Kb / 15P
   Dual Low Power Frequency Synthesiser
SP8861 MITEL-SP8861 Datasheet
200Kb / 13P
   1쨌3GHz Low Power Single-Chip Frequency Synthesiser
logo
Zarlink Semiconductor I...
SP8861 ZARLINK-SP8861 Datasheet
282Kb / 15P
   1쨌3GHz Low Power Single-Chip Frequency Synthesiser
WL800 ZARLINK-WL800 Datasheet
573Kb / 12P
   2.5GHz Frequency Synthesiser
logo
Mitel Networks Corporat...
SP5730 MITEL-SP5730 Datasheet
372Kb / 14P
   1.3GHz Low Phase Noise Frequency Synthesiser
WL800 MITEL-WL800 Datasheet
150Kb / 11P
   2.5GHz Frequency Synthesiser
logo
Zarlink Semiconductor I...
NJ8820 ZARLINK-NJ8820 Datasheet
493Kb / 11P
   FREQUENCY SYNTHESISER (PROM INTERFACE)
SP5730 ZARLINK-SP5730 Datasheet
380Kb / 12P
   1.3 GHz Low Phase Noise Frequency Synthesiser
SP5768 ZARLINK-SP5768 Datasheet
104Kb / 10P
   3.0 GHz Low Phase Noise Frequency Synthesiser
logo
Mitel Networks Corporat...
NJ88C33 MITEL-NJ88C33 Datasheet
155Kb / 11P
   Frequency Synthesiser (I2C BUS Programmable)
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com