2 Ch. LVPECL to NCML Level Translator


$ 718.75


  • Converting Single-ended or Differential LVPECL Inputs to Differential NCML Outputs
  • Differential LVPECL Inputs also accept Sinewave Signals
  • High Speed Digital Communications System Testing
  • Satellite/Radar/Telecommunications System Integration


  • fMAX > 1.5 GHz
  • 650 ps tr
  • 50 Ω/+1.3 V LVPECL Input Termination
  • Complementary NCML Outputs
  • DC Coupled SMA I/O Connectors
  • Self-contained 1.3H x 2.9W x 3.9D unit includes AC/DC adapter


The PRL-427LP is a 2-channel LVPECL to differential NCML Logic Level Translator module. Each channel has a single-ended or differential LVPECL input and a ground-referenced differential 35 Ω NCML output. The NCML DC output logic Hi/Lo levels are 0 V and -350 mV, respectively, when terminated to ground-referenced 50 Ω loads.

A switch selects either single-ended or differential inputs, as shown in Fig. 1. In the differential input mode, both inputs D and D are terminated internally into 50 Ω/VTT, where VTT is equal to +1.3 V for LVPECL. In the differential input mode, therefore, either one or both inputs can accept AC coupled signals as well. In the single input mode, signals should be connected to the D inputs only. The D inputs are switched internally to VBB, nominally +2.0 V for LVPECL, and termination resistors RT for the D input channels are changed to 62 Ω.

These Logic Level Translators are designed specifically for use in testing and interfacing of high speed digital communications circuits, where conversion between LVPECL and NCML logic signals is often required. The PRL-427LP is part of the Mini Modular Instrument™ (MMI) family that find increasing applications in high speed digital data recording instruments, transient recording instruments and other high speed measurement equipment where LVPECL and NCML signals are often specified.

Fig. 1 PRL-427LP Block Diagram

(0° C ≤ TA ≤ 35° C)*

Unless otherwise specified, all logic level and dynamic measurements are made with all outputs terminated into 50 Ω/VTT, where VTT = 0 V for NCML outputs.

Min Typ Max
RIN Input Resistance 49.5 50.0 50.5 Ω
ROUT Output Resistance   35   Ω
VTT D Input Termination Voltage (fixed) 1.18 1.30 1.43 V
VT1 D Input Termination Voltage 1.18 1.30 1.43 V
VT2 D Input Termination Voltage (variable) 1.80 2.00 2.20 V
VIL Input Lo Voltage 1.35 1.48 1.67 V
VIH Input Hi Voltage 2.08 2.28 2.42 V
VOL DC Output Low Level -0.35 V
VOH DC Output High Level 0 V
VOPP1 Output Logic Swing from DC-500MHz 300 350 mV
VOPP2 Output Logic Swing from 500MHz-1GHz 275 300 mV
VOPP3 Output Logic Swing from 1GHz -1.5GHz 225 260 mV
VOCM Output Common Mode Voltage -200 mV
IDC1 DC Input Current, +8.5 V 160 mA
IDC2 DC Input Current, -8.5 V -315 mA
VDC DC Input Voltage ±7.5 ±8.5 ±12.0 V
VAC AC/DC Adapter Input Voltage 108 120 132 V
tPLH Propagation Delay to output ↑ 1.5   ns
tPHL Propagation Delay to output ↓ 1.5   ns
tR/tF Rise/Fall Times (10-90%)   650 750 ps
TSKEW Skew between any 2 outputs 40 75 ps
VINI Minimum Input Voltage @ 150 MHz 20 10 mVpp
VINII Minimum Input Voltage @ 250 MHz 20 10 mVpp
fMAX Max Clock Frequency 1250 1500 MHz
  Size 1.3H x 2.9W x 3.9D in.
  Weight, excluding AC adapter 7 Oz
  Shipping weight, including AC adapter 4 lb.
For the PRL-427LP, very slight output waveform distortion and rise time degradation will occur when an unused complementary output is not terminated. For optimum performance, however, all outputs should be terminated.