  A new cryogenic noise calibration source for radio astronomy receivers is
presented. Dissipated power is only 4.2 mW, allowing it to be integrated with
the cold part of the receiver. Measured long-term stability, sensitivity to
bias voltages, and noise power output versus frequency are presented. The
measured noise output versus frequency is compared to a warm noise diode
injected into cryogenic K-band receiver and shows the integrated noise module
to have less frequency structure, which will result in more accurate
astronomical flux calibrations. It is currently in operation on the new
7-element K-band focal plane array receiver on the NRAO Robert C. Byrd Green
Bank Telescope (GBT).
