Low-frequency noise in permeable base transistors

The predominant noise is1/fnoise and consists of two parts: a) Noise varying asImin{C}max{2}, generated mostly with conducting channel and predominating for normal values of the collector voltage VCE. b) Noise at low VCEand practically independent of VCE; it is generated chiefly in the space charge region around the base grating and gives collector1/fnoise atV_{CE} = 0. The turnover frequency of the first noise source lies at about 20 MHz forV_{CE} = 0.30V,V_{BE} = 0.20V. At sufficiently high frequencies the PBT shows thermal noise of the output conductanceg_{c0}at zero bias. Generation-recombination noise is observed at large VBEand low VCEand comes mostly from the space charge region around the base grating.