2 Channel Comparator, RS-422 Outputs

Applications:

• Window Comparators
• High Speed Timing
• Line Receivers
• Threshold Detection
• Peak Detection
• RS-422 Translation

Features:

• f_MAX > 500 MHz
• 1.1ns Typical t_r
• +50 mV, 0 V or -50 mV Preset Input Threshold Voltage
• -2.0 V to +3.0 V Input Common Mode Range
• 10 mV_PP Minimum Input @ 100 MHz.
• DC Coupled 50 Ω Inputs
• Differential 124 Ω Outputs
• SMA inputs with SMA or Triax Output Connectors
• Self-contained 1.3 x 2.9 x 3.9-in. unit includes AC/DC Adapter

Description

The PRL-350RS is a ready-to-use, high-speed, dual-channel comparator module with RS-422 outputs. The PRL-350RS has a typical maximum clock frequency in excess of 500 MHz and has differential RS-422 outputs designed for driving floating 124 Ω transmission lines.

The PRL-350RS has DC-coupled 50 Ω inputs and differential 124 Ω 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, or varied independently for each channel by applying a DC bias voltage to one of the two inputs. 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 V_TH, and the toggle switch setting is a don’t-care.
• For an external shunt resistor, the effective threshold voltage, V_THE, will be the result of the resistor-divider network formed by the external shunt resistor and the internal 50 Ohm termination to the selected V_TH.
• In the following example, the internal V_TH is set to +50 mV, and it is pulled down to an effective V_THE of +10 mV via a 12.5 Ω shunt resistor:
• 
• This technique is typically provides a more useful operating range when using the PRL-350RS-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, sinewave-to-square wave converters, window comparators or differential line receivers, etc. The typical minimum input voltage of 10 mV_PP is required for up to 100 MHz. It is recommended that the non-driven input be terminated into 50 Ω when the input frequency is near f_MAX and its amplitude is less than 20 mV_PP.

The PRL-350RS model has SMA input and output connectors. The PRL-350RSTR has SMA inputs and Triax output connectors. Each unit is supplied with a ±8.5 V AC/DC Adapter and housed in a 1.3 x 2.9 x 3.9-in. extruded aluminum enclosure