A theory of high-frequency distortion in bipolar transistors

High-frequency distortion in bipolar transistors is examined by using the charge-control approach of Pooh and Narayanan to connect the device's distortion behavior to its "loaded" unity-current-gain frequency (ω̂T). The resulting expressions for the distortion reveal considerable information on its frequency and bias dependence. Points on the ω̂T versus collector current curve yielding optimum distortion performance are identified and interpreted in terms of current cancellation. Both second- and third-order distortion are considered, and the results are validated by both simulation and experiment.