  Cosmic microwave background experiments have experienced an exponential
increase in complexity, data size and sensitivity. One of the goals of current
and future experiments is to characterize the B-mode power spectrum, which
would be considered a strong evidence supporting inflation. The signal
associated with inflationary B-modes is very weak, and so a successful
detection requires exquisite control over systematic effects, several of which
might arise due to the interaction between the electromagnetic properties of
the telescope beam, the scanning strategy and the sky model. In this work, we
present the Pixel Space COnvolver (PISCO), a new software tool capable of
producing mock data streams for a general CMB experiment. PISCO uses a fully
polarized representation of the electromagnetic properties of the telescope.
PISCO also exploits the massively parallel architecture of Graphic Processing
Units to accelerate the main calculation. This work shows the results of
applying PISCO in several scenarios, included a realistic simulation of an
ongoing experiment, the Cosmology Large Angular Scale Surveyor.
