Applications:


Features:


DescriptionThe PRL2578 is an ACcoupled input, manually programmable, two phase frequency divider with two sets of complementary NECL outputs. It is capable of running at input frequencies in excess of 12 GHz. It has a common divideby8 prescalar front end followed by two banks of independent manually programmable dividers, Φ1and Φ2. The f/8 prescalar output is further divided by 1, 2, 4, or 8 for the Φ1 bank via D0 and D1 of a twobit DIP switch, providing a maximum ratio of 64. It is divided by 2, 4, 8 or 16 for the Φ2 bank via D2 and D3 of a second twobit DIP switch, providing a maximum ratio of 128. All outputs are synchronous with the input frequency and are square waves (50% duty cycle) suitable for driving long lines terminated into 50 Ω/2 V or ACcoupled 50 Ω loads. The PRL2578 is ideal for applications where a high frequency divider or prescalar is needed for triggering or downsampling. The two phases of output enable applications requiring two different ratios from a common reference frequency, and the 1:2 fanout feature enables system synchronization and monitoring/triggering applications from a single reference clock source. Applications for the PRL2578 include data acquisition, test, measurement, R&D, and system integration. The unit includes an AC adapter for readytouse convenience on the bench or in a system. All I/O connectors are SMA. The extruded aluminum housing is suitable for mounting with the optional brackets. 
Fig. 2: PRL2578 Block Diagram
Sample Applications and Test Results
The PRL2578 was reviewed by a wellrespected member of the Signal Integrity mailing list:
". . . the device has a [specified] bandwidth up to 12GHz, and my measurements show that its actual bandwidth goes out to 14GHz. I thought that was very good margin. But what really impressed me was the jitter performance. I fed in a clock source with 170fs one sigma RJ, and the clock divider puts out a divided down clock with 770fs one sigma RJ. That is surprisingly good for a small device with such high bandwidth. Usually you would expect this kind of performance from a device weighing 40 lb and takes up a whole lot of bench top space, but this clock divider is small enough to fit in your pocket."
The full review is available at the silist archives.
Scope shots from his testing are below:
Fig. 3: PRL2578 Output Waveform, 14 GHz input clock divided by 64
Fig. 4: PRL2578 Jitter Performance*, 10.3125 GHz clock divided by 8
Fig. 5: PRL2578 Jitter Performance*, 10.3125 GHz clock divided by 64
Fig. 6: PRL2578 Jitter Performance*, 2.125 GHz clock divided by 8
* These test results, though typical, are not guaranteed performance specifications.
SPECIFICATIONS (0° C ≤ T_{A} ≤ 35° C)*
Symbol  Parameter  PRL2578  Unit  Comments  

Min  Typ  Max  
R_{IN}  Input Resistance  50  Ω  AC Coupled  
C_{C}  Coupling Capacitor  0.08  0.10  0.12  µf  Input TC=50 µs 
V_{INmin}  Minimum pp Input Amplitude  500 350 100 
400 250 50 
mV mV mV 
Sine Wave@ F_{MIN In I} Square Wave, tr <2ns Square Wave, tr <500ps 

V_{INmax}  Maximum pp Input Amplitude  2.00  1.25  V  Sine or Square Wave  
V_{OL}  Output Lo Voltage @ 100 MHz  1.95  1.60  1.48  V  Output terminated to 50 Ω/2V 
V_{OH}  Output Hi Voltage @ 100 MHz  1.13  0.90  0.81  V  Output terminated to 50 Ω/2V 
I_{DC1}  DC Input Current, +8.5 V  +80  +100  mA  
I_{DC2}  DC Input Current, 8.5 V  285  300  mA  
V_{DC}  DC Input Voltage  ±7.5  ±8.5  ±12  V  
V_{AC}  AC/DC Adapter Input Voltage  103  115  127  V  
t_{PLH}  Propagation Delay to Φ1 output ↑  2500  ps  
t_{PHL}  Propagation Delay to Φ1 output ↓  2500  ps  
t_{r}/t_{f}  Rise/Fall Times (20%80%)  200  250  ps  Note (1)  
t_{SKEW1}  Skew↔ Φ1 or Φ2 outputs  40  120  ps  
t_{SKEW2}  Skew↔ Φ1 and Φ2 outputs  40  120  ps  D0/D1=10, D2/D3=00  
Jitter, pp  5  10  ps  Note (2)  
F_{MIN In I}  Minimum Input frequency  120  100  MHz  Sine wave input  
F_{MIN In II}  Minimum Input frequency  150  100  KHz  Square wave input  
F_{MAX In I}  Maximum Input frequency  10.0  12.0  12.5  GHz  
F_{MAX Out1}  Maximum Output frequency, Φ1  1.25  1.50  1.56  GHz  Φ1 outputs 
F_{MAX Out2}  Maximum Output frequency, Φ2  0.625  0.750  0.780  GHz  Φ2 outputs 
Size  1.3 x 2.9 x 2.9  in.  
Weight, excl. AC adapter  10  Oz.  
Shipping weight, incl. AC adapter  3  lb. 