A theory of high-frequency distortion in bipolar transistors

High-frequency distortion in bipolar transistors is examined by using the charge-control approach of Poon and Narayanan (H.C. Poon, IEEE Trans. Electron Dev., vol. ED-19, pp. 719-731, 1972; S. Narayanan and H.C. Poon, IEEE Trans. Circuit Theory, vol. CT-20, pp. 341-351, 1973; H.C. Poon, IEEE Trans. Electron Dev., vol. ED-21, pp. 110-112, 1974) to connect the device\´s distortion behavior to its "loaded" unity-current-gain frequency (ωˆ_T). The resulting expressions for the distortion reveal considerable information on its frequency and bias dependence. Points on the ωˆ_T 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.