  The C-Band All-Sky Survey (C-BASS) is a project to map the full sky in total
intensity and linear polarization at 5 GHz. The northern component of the
survey uses a broadband single-frequency analogue receiver fitted to a 6.1-m
telescope at the Owens Valley Radio Observatory in California, USA. The
receiver architecture combines a continuous-comparison radiometer and a
correlation polarimeter in a single receiver for stable simultaneous
measurement of both total intensity and linear polarization, using
custom-designed analogue receiver components. The continuous-comparison
radiometer measures the temperature difference between the sky and
temperature-stabilized cold electrical reference loads. A cryogenic front-end
is used to minimize receiver noise, with a system temperature of $\approx
30\,$K in both linear polarization and total intensity. Custom cryogenic notch
filters are used to counteract man-made radio frequency interference. The
radiometer $1/f$ noise is dominated by atmospheric fluctuations, while the
polarimeter achieves a $1/f$ noise knee frequency of 10 mHz, similar to the
telescope azimuthal scan frequency.
