Option M5i.3321-inptd - Time Domain Input Stage Optimization

This option is only available for the M4i.3321-x16 (2 x 3.2 GS/s 12 Bit Digitizer with 1 GHz bandwidth).This option changes the hardware input filter of the card and is not software.switchable. The option can only be installed inn factory as soldering work and factory calibration are needed.

The -inptd option optimizes the input stage for time domain measurement with a modified filter characteristic to minimize overshoot and undershoot on step response. The standard filter is optimized for frequency domain measurements with a very steep cut-off frequency. This steep cut-off frequency results in some overshoot/undershoot and ringing when feeding the system with step signals.

Filter Characteristics

The right-hand picture shows the filter characteristics of the original filter (Red, Channel 1) with a very steep -3 dB cut-off at a little above 1 GHz. This filter has an attenuation of weel above -20 dB at a frequency of 1.2 GHz.

In contrast the modified filter of the -inptd-option (Blue, Channel 0) has a very smooth characteristic without a steep cut-off. The filter allows signal frequenies up to the 2 GHz content with only -10 dB attenuation.

Time Domain Measurement

The right-hand picture shows the step response measurements on the original filter (red) in comparison to the modified inptd-filter (blue).