The PRL-257-8 is an AC-coupled 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 divide-by-8 pre-scalar front end followed by two banks of independent manually programmable dividers, Φ1and Φ2. The f/8 pre-scalar output is further divided by 1, 2, 4, or 8 for the Φ1 bank via D0 and D1 of a two-bit 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 two-bit 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 AC-coupled 50 Ω loads.
The PRL-257-8 is ideal for applications where a high frequency divider or pre-scalar is needed for triggering or down-sampling. 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 PRL-257-8 include data acquisition, test, measurement, R&D, and system integration.
The unit includes an AC adapter for ready-to-use 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: PRL-257-8 Block Diagram
Sample Applications and Test Results
The PRL-257-8 was reviewed by a well-respected 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 si-list archives.
Scope shots from his testing are below:
Fig. 3: PRL-257-8 Output Waveform, 14 GHz input clock divided by 64
Fig. 4: PRL-257-8 Jitter Performance*, 10.3125 GHz clock divided by 8
Fig. 5: PRL-257-8 Jitter Performance*, 10.3125 GHz clock divided by 64
Fig. 6: PRL-257-8 Jitter Performance*, 2.125 GHz clock divided by 8
* These test results, though typical, are not guaranteed performance specifications.
SPECIFICATIONS (0° C ≤ TA ≤ 35° C)*
|RIN||Input Resistance||50||Ω||AC Coupled|
|CC||Coupling Capacitor||0.08||0.10||0.12||µf||Input TC=50 µs|
|VINmin||Minimum p-p Input Amplitude||500
|Sine Wave@ FMIN In I
Square Wave, tr <2ns
Square Wave, tr <500ps
|VINmax||Maximum p-p Input Amplitude||2.00||1.25||V||Sine or Square Wave|
|VOL||Output Lo Voltage @ 100 MHz||-1.95||-1.60||-1.48||V||Output terminated to 50 Ω/-2V|
|VOH||Output Hi Voltage @ 100 MHz||-1.13||-0.90||-0.81||V||Output terminated to 50 Ω/-2V|
|IDC1||DC Input Current, +8.5 V||+80||+100||mA|
|IDC2||DC Input Current, -8.5 V||-285||-300||mA|
|VDC||DC Input Voltage||±7.5||±8.5||±12||V|
|VAC||AC/DC Adapter Input Voltage||103||115||127||V|
|tPLH||Propagation Delay to Φ1 output ↑||2500||ps|
|tPHL||Propagation Delay to Φ1 output ↓||2500||ps|
|tr/tf||Rise/Fall Times (20%-80%)||200||250||ps||Note (1)|
|tSKEW1||Skew↔ Φ1 or Φ2 outputs||40||120||ps|
|tSKEW2||Skew↔ Φ1 and Φ2 outputs||40||120||ps||D0/D1=10, D2/D3=00|
|Jitter, p-p||5||10||ps||Note (2)|
|FMIN In I||Minimum Input frequency||120||100||MHz||Sine wave input|
|FMIN In II||Minimum Input frequency||150||100||KHz||Square wave input|
|FMAX In I||Maximum Input frequency||10.0||12.0||12.5||GHz|
|FMAX Out1||Maximum Output frequency, Φ1||1.25||1.50||1.56||GHz||Φ1 outputs|
|FMAX 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.|