2 Channel Comparator, TTL Outputs


$ 1,229.35


  • Window Comparators
  • High Speed Timing
  • Line Receivers
  • Threshold Detection
  • Peak Detection
  • PON Module testing with Anritsu MP1800A


  • fmax > 300 MHz
  • 1.1ns Typical tr 
  • +50 mV, 0 V or -50 mV Preset Input Threshold Voltage
  • -2.0 V to +3.0 V Input Common Mode Range
  • 10 mVPP Minimum Input @ 300 MHz.
  • DC Coupled 50 Ω Inputs
  • Complementary TTL Outputs
  • SMA I/O Connectors
  • Self-contained unit includes AC/DC Adapters


The PRL-350TTL is a ready-to-use, high speed dual-channel comparator module. The  The PRL-350TTL has a maximum clock frequency in excess of 300 MHz and has complementary TTL outputs designed for driving 50 Ω transmission lines with or without 50 Ω load terminations.

All models have DC coupled 50 Ω inputs and outputs. The input threshold voltage can be selected either from a set of preset values of +50 mV, 0 V or 50 mV using a common three-position switch. The input common mode range is -2.0 V to +3.0 V.

The input threshold voltage can also be varied independently in each channel by applying an external DC bias voltage or shunt resistor to the D input.

  • If the external DC bias has a sufficiently low output impedance, it will over-ride the internally-generated VTH, and the toggle switch setting is a don’t-care.
  • For an external shunt resistor, the effective threshold voltage, VTHE, will be the result of the resistor-divider network formed by the external shunt resistor and the internal 50 Ohm termination to the selected VTH.
  • In the following example, the internal VTH is set to +50 mV, and it is pulled down to an effective VTHE of +10 mV via a 12.5 Ω shunt resistor:
  • This technique is typically provides a more useful operating range when using the PRL-350TTL-NIM, with settable ±400 mV thresholds.
  • To prevent oscillation, the external shunt resistor should be placed as close as possible to the D input, e.g. by using the male end of the PRL-PINET-SMF or similar device.

These high speed comparators are Mini Modular Instruments™ that can be used as peak detectors, threshold detectors, sine wave to square wave converters, window comparators or differential line receivers, etc. Typical minimum input voltage required at 300 MHz is 10 mVPP. into 50 Ω.

Each unit is supplied with a ±8.5 V AC/DC Adapter and housed in an attractive 1.3 x 2.9 x 3.9-in. extruded aluminum enclosure.

Fig. 1B PRL-350TTL Block Diagram

For the PRL-350TTL, 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.

Anritsu Application Note for PON Module Testing with Anritsu MP1800A
Signal Quality Analyzer and PRL-350 Series Comparators (1.1 MB PDF)

BERT Level Translation

Anritsu engineers and customers around the world rely on our PRL-350 Series comparators for level conversion when testing Passive Optical Network (PON) modules.

PON module testing often requires converting the -1.0 to 0 V signals output by the MU181020A Pulse Pattern Generator cards to the LVTTL, PECL or LVPECL levels required by many ONU and OLT modules, typically for the Data, Pre-bias, and Reset signals.

Popular models include:

  • PRL-350TTL, Dual Channel Comparator with TTL Outputs
  • PRL-350LP, Dual Channel Comparator with LVPECL Outputs
  • PRL-350P, Dual Channel Comparator with PECL Outputs

App Note and block diagram copyright and courtesy of Anritsu Corporation.

(0° C ≤ TA ≤ 35° C)*

Unless otherwise specified, dynamic measurements are made with all outputs terminated into 50 Ω.

Symbol Parameter PRL-350TTL Unit
Min Typ Max
RIN Input Resistance 49.5 50 50.5 Ω
ROUT Output Resistance 49.5 50 50.5 Ω
VTH+ Preset positive threshold voltage 45 50 55 mV
VTH- Preset negative threshold voltage -55 -50 -45 mV
VTH0 Preset zero threshold voltage(1) -2 0 2 mV
VOL Output Low Level -0.5 0 0.5 V
VOH Output High Level 2.0 2.2 2.4 V
IDC1 DC Input Current, +8.5 V 300 325 mA
IDC2 DC Input Current, -8.5 V -285 -300 mA
VDC1 DC Input Voltage, +8.5 V 7.5 8.5 12.0 V
VDC2 DC Input Voltage, -8.5 V -12.0 -8.5 -7.5 V
VAC1 AC/DC Adapter Input Voltage, 120 VAC 103 115 127 V
VAC2 AC/DC Adapter Input Voltage, 220 VAC 206 230 254 V
tPLH Propagation Delay to output↑ 2 ns
tPHL Propagation Delay to output↓ 2 ns
tr/tf Rise/Fall Times, 10% - 90% 1100 1250 ps
tSKEW Skew between any 2 outputs 200 400 ps
Vin I Minimum Input Voltage @ 150 MHz(2) 20 10 mVPP
Vin II Minimum Input Voltage @ 250 MHz(2) 40 20 mVPP
VCM Input Common Mode Range -2.0 +3.0 V
fmax Max. Clock Frequency 250 300 MHz
Size 1.3 x 2.9 x 3.9 in.
Weight, w/o AC adapter 7 Oz
Shipping weight, w/AC adapter 4 lb

(1) If the switch is set to the center position (0 V threshold) a non-driven channel will oscillate and induce jitter in the driven channel. Connect any output to any input to stop the oscillation.

For the PRL-350TTL, 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.

(2) In order to reduce jitter near fMAX, terminate the non-driven input into 50 Ω when the input voltage is less than 20 mVPP.

While we believe these models to be accurate, no representations are made as to accuracy or suitability for any application: