  We describe here a focal plane array of Cold-Electron Bolometer (CEB)
detectors integrated in a Frequency Selective Surface (FSS) for the 350 GHz
detection band of the OLIMPO balloon-borne telescope. In our architecture, the
two terminal CEB has been integrated in the periodic unit cell of the FSS
structure and is impedance matched to the embedding impedance seen by it and
provides a resonant interaction with the incident sub-mm radiation. The
detector array has been designed to operate in background noise limited
condition for incident powers of 20 pW to 80 pW, making it possible to use the
same pixel in both photometric and spectrometric configurations. We present
high frequency and dc simulations of our system, together with fabrication
details. The frequency response of the FSS array, optical response measurements
with hot/cold load in front of optical window and with variable temperature
black body source inside cryostat are presented. A comparison of the optical
response to the CEB model and estimations of Noise Equivalent power (NEP) is
also presented.
