So i m about to design a simple trans-impedance amplifier using a pulsed current source as an input.
How can i introduce high frequency voltage spikes ? Can i put together a voltage and current source?
I'm not quite sure why you'd be using a voltage and current source, however you should be able to use some of the different voltage sources found on the SIGNAL_VOLTAGE_SOURCES, or the CONTROLLED_VOLTAGE_SOURCES sections to introduce the noise, which one would be the best fit I think would mostly depend on what are the characteristics you want for the noise.
I need the current source to simulate the current pulse fed to the TIA and some sort of voltage source to overlay high frequency noise (1-10 MHz could be a sine wave or delta function spikes) which is coupled to the input of TIA. In the real circuit the source of the noise is unknown, could be noise from the switchers or picked up from somewhere else.