Characterization of Zero-Bias Microwave Diode Power Detectors at Cryogenic Temperature

International audienceWe present the characterization of commercial tunnel diode low-level microwave power detectors at room and cryogenic temperatures. The sensitivity as well as the output voltage noise of the tunnel diodes are measured as functions of the applied microwave power. We highlight strong variations of the diode characteristics when the applied microwave power is higher than few microwatt. For a diode operating at 4 K, the differential gain increases from 1, 000 V/W to about 4, 500 V/W when the power passes from √ −30 dBm to −20 √ dBm. The diode white noise floor is equivalent to a Noise Equivalent Power of 0.8 pW/ Hz and 8 pW/ Hz at 4 K and 300 K respectively. Its flicker noise is equivalent to a relative amplitude noise power spectral density S α (1 Hz) = −120 dB/Hz at 4 K. Flicker noise is 10 dB higher at room temperature