Question

4. Briefly describe any two of Johnson's power frequency limitation for conventional transistors at microwave frequency. Mention the assumptions and postulates with basic mathematical relations.

Answer 1

A) Reaer- Fragueny Limito tiens pauer eeency limitalios a) The limitng veloaty Caiers The introduced becaure o were Semi cenducters Feld allainable enset o avalanche mulliplicalum cai thout the 6 the maximum sem'conduc lors The astump tuors and poitulats by Johnon ore veloudy Called attain The Semicenducler marimur Carerriers the order of duift veloaty Salwra led and Vs as an d germanium Silicon electrons and hales in 6 X10 cm/s foy can be elbcbeie held E that 2There is maximur reeakdeesn dielectue heving without Semiconductor Sustaincd in a 2x10 /em and germaniu about i's tr This silicon tseansisler tworent that micwwave pewer a maximum 3) The lirmikd oy base Cai d th carry Can relateons Mathematical irmitalibyne Voltage- Freguuney Em Vs Von tr EmLmin Vm= 2 fagurney tronsit-time utoff change Carraes ield Marimum electic Em) veloaty drift Saturated

Fraquency Linila bo (Tm Xe)f 2) Currunt Em Vs T 2 11 device Tm Maximum avrent of the eeaitive Impedance the i's 2Tr Co Pouser- rguerey Limta tion 1 Em Vs 2 T Pam=Vm Tm