2 Ch. Translator, TTL to PECL


$ 661.25


  • Converting TTL/CMOS signals to Differential PECL Signals
  • High Speed Digital Communications system testing
  • High Speed SONET Clock Level Translation
  • Converting TTL/CMOS Clocks to PECL Clocks for connection to Transient Recorders


  • fMAX > 300 MHz
  • 1100 ps tr
  • 50 Ω TTL/CMOS Input
  • 1.5 V or 1.0 V Selectable Input Threshold
  • Complementary PECL Outputs
  • BNC Input, SMA Output Connectors
  • DC-Coupled I/Os
  • Self-contained 1.3 x 2.9 x 3.9-in. units including AC/DC Adapters


The PRL-420PD translator converts TTL/CMOS logic to PECL levels. 

Each unit has a switch-selectable 1.5 V or 1 V input threshold voltage, with a 50  fixed input termination. The complementary PECL outputs from the PRL-420PD are suitable for driving 50 Ω loads terminated to +3 V. The outputs of all units can also drive AC-coupled or floating 50 Ω loads.

These Logic Level Translators are designed specifically for use in testing and interfacing of high speed digital communications circuits, where conversions from TTL/CMOS level signals to PECL level signals are often required. They are ideal building blocks that complement other PRL Logic Level Translators, such as the PRL-450ND, PRL-450PD, PRL-460NPD and PRL-460PND, etc. in systems integration applications where interconnections of mixed logic signals are often necessary.

They are ready-to-use functional modules housed in 1.3 x 2.9 x 3.9-in. extruded aluminum enclosures and are supplied with ±8.5V AC/DC Adapters. All units have BNC input connectors and SMA output connectors. A block diagrams is shown in Fig. 1.

If mounting is desired, a pair of 35001420 mounting brackets can accommodate two PRL modules of the same length. A number of PRL modules can also share a single ±8.5V AC/DC adapter using the PRL-730 or PRL-735 voltage distribution module.

Fig. 1, PRL-420PD Block Diagram

(0° C ≤ TA ≤ 35° C)*

Symbol Parameter PRL-420PD Unit
Min Typ Max
RIN Input Resistance 49.5 50 50.5
ROUT Output Resistance 49.5 50 50.5
VTOSH Input Threshold Voltage (High) 1.4 1.5 1.6 V
VTOSL Input Threshold Voltage (Low) 0.9 1.0 1.1 V
VOL Output Low Level 3.2 3.4 3.5 V
VOH Output High Level 3.9 4.1 4.3 V
IDC1 DC Input Current, +8.5 V 180 200 mA
IDC2 DC Input Current, -8.5 V -315 -335 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 output ↑ 2 ns
tPHL Propagation Delay to output ↓ 2 ns
tr/tf(1) Rise/Fall Times (20%-80%) 1100 1250 ps
tSKEW1 Skew: VO↑↔VO 200 500 ps
tSKEW2 Skew: VO1↑↔ VO2 200 500 ps
Max Clock Frequency
Input Threshold Voltage (High)
200 300 MHz
Max Clock Frequency
Input Threshold Voltage (Low)
300 400 MHz
Size 1.3 x 2.9 x 3.9 in.
Weight, excl. AC adapter 7 Oz
Shipping weight, incl. AC adapter 4 lb.

*Unless otherwise specified, dynamic measurements are made with all outputs terminated into 50 Ω /-2 V for PRL420ND and 50 Ω/3 V for PRL-420PD.


The output rise and fall times are measured with with all inputs terminated into 50 Ω/VTT. For best performance all outputs should be terminated into 50 Ω/VTT or else AC- coupled into 50 Ω loads. If a single output is used, its complement must be terminated; otherwise output waveform distortion will occur. If one pair of complementary outputs is used, the other complementary pair may remain unterminated. Use the PRL-550PQ4X, four channel PECL Terminator, for the 50 Ω/VTT termination and for connection of PECL signals to 50 Ω input oscilloscopes. The PRL-ACT-50, Dual Channel AC-Coupled 50 Ω Terminator, may also be used to provide the 50 Ω/VTT termination. If preservation of DC levels is not required, then the PRL-SC-104, 0.1 µf DC block or a 12 dB AC-coupled attenuator may be used to connect the PECL outputs to 50 Ω input instruments.

(2). fMAX for the PRL-420PD is measured using the PRL-450PD as the input driver, and its outputs are connected to the differential inputs of the PRL-255P PECL frequency divider. The outputs of the PRL 255P are then measured using the PRL-550PQ4X, four channel PECL Terminators, connected to a 50 Ω input sampling 'scope.