  We give a semiclassical analysis of the average photon number as well as
photon number variance (Fano factor $F$) for a Josephson-junction (JJ) embedded
microwave cavity system, where the JJ is subject to a fluctuating (i.e. noisy)
bias voltage with finite dc average. Through the ac Josephson effect, the dc
voltage bias drives the effectively nonlinear microwave cavity mode into an
amplitude squeezed state ($F<1$), as has been established previously [A. D.
Armour, et al., Phys. Rev. Lett. 111, 247001 (2013)], but bias noise acts to
degrade this squeezing. We find that the sensitivity of the Fano factor to bias
voltage noise depends qualitatively on which stable fixed point regime the
system is in for the corresponding classical nonlinear steady state dynamics.
Furthermore, we show that the impact of voltage bias noise is most significant
when the cavity is excited to states with large average photon number.
