High Speed Voltage to Current Converter

[luky315]

I want to measure the frequency response of a high speed transimpedance amplifier (2GHz) Signal chain including filter and post gain stage with an NWA. So I have to convert the stimulus signal (-40 to -10dBm) to a current. The lowest relevant Input ist arround 1-2uA so for a -40dBm Signal a 1-2k resistor ist needed. The question ist, if a few simple passive resistors (I found 250R with a reasonable flat impedance up to 3 GHz) would be OK or if a high speed Opamp based solution would perform better? Has anyone experiences with this sort of signals?