  SiGe BiCMOS technology can be used to produce ultra-fast, low-power silicon
pixel sensors that provide state-of-the-art time resolution even without an
internal gain mechanism. The development of such sensors requires the
identification of the main factors that may degrade the timing performance and
the characterisation of the dependance of the sensor time resolution on the
amplifier power consumption. Measurements with a $ \mathrm{^{90}Sr} $ source of
a prototype sensor produced in SG13G2 technology from IHP Microelectronics,
shows a time resolution of 140 ps at an amplifier current of 7 $ \mathrm{\mu}
$A and 45 ps at higher power consumption. A full simulation shows that the
resolution on the measurement of the signal time-over-threshold, used to
correct for time walk, is the main factor affecting the timing performance.
