2 Ch. Comparator, NIM-compatible Outputs


$ 1,397.25


  • Window Comparators
  • Zero crossing Detectors
  • High Speed Timing
  • Line Receivers
  • Threshold Detection
  • Peak Detection
  • Sine Wave to Square Wave Converters


  • fmax > 300 MHz
  • 450 ps tr/tff
  • +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 @ 150 MHz.
  • DC Coupled 50 Ω Inputs
  • 0 V to -800 mV complementary outputs into 50 Ω
  • SMA I/O Connectors
  • Self-contained units include AC/DC Adapters


The PRL-350NIM is a high-speed dual-channel comparator modules with complementary 0 V to -800 mV NIM outputs. The PRL-350NIM is designed for driving 50 Ω transmission lines terminated to 50 Ω. All outputs of the PRL-350NIM are 50Ω back terminated and must be terminated into 50Ω for optimum performance.

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, or varied independently in each channel by applying a DC voltage to one of the two inputs. 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-350NIM-NIM (special order), 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 150 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. 1 PRL-350NIM Block Diagram

(0° C ≤ TA ≤ 35° C)*

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

Symbol Parameter PRL-350NIM Unit
Min Typ Max
RIN Input Resistance 49.5 50.0 50.5 Ω
ROUT Output Resistance 49.5 50.0 50.5 Ω
VTH+ Preset positive threshold voltage 49.5
50.0 50.5
VTH- Preset negative threshold voltage -50.5
VTH0 Preset zero threshold voltage(1) -10
0 10
VOL Output Low Level -875
VOH Output High Level -50
IDC1 DC Input Current, +8.5 V 20
IDC2 DC Input Current, -8.5 V -275

VDC1 DC Input Voltage, +8.5 V 7.5 8.5 12.0 V
VDC1 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↑ 1.5
tPHL Propagation Delay to output↓ 1.5
tr/tf Rise/Fall Times, 10% - 90% 450
tSKEW Skew between any 2 outputs 450
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 300
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 may oscillate and induce jitter in the driven channel. Connect any output to any input to stop the oscillation.

(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: