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DescriptionThe 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)*
Symbol | Parameter | PRL-257-8 | Unit | Comments | ||
---|---|---|---|---|---|---|
Min | Typ | Max | ||||
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 | 500 350 100 |
400 250 50 |
mV mV mV |
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. |