Budapest University of Technology and Economics Department of Electron Devices Microelectronics, BSc course Bipolar IC transistor 4 Look at it as individual work.

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Small signal equivalents of bipolar transistors

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET The small signal operation Finding the operating point In Out

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET The small signal operation AC equivalents for the passives components In Out & the BJT In Out In Out

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Different equivalents 1. physical "two element" "three element” "five elemenet" 2. "Black box" (two-port) h parameter y parameter s parameter For all: common base / common emitter setups

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents 2 elelement I E linearly controls I C finite input resistance common base

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents 2 element, common base

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents 2 element, common emitter common emitter

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents 2 element c.b.c.e.

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents The small signal current gain of a BJT in the I E = 1 mA operating point is  = 200. Find the element values of its AC equivalents in the common base and common emitter setups! c.b. c.e. Problem 2 element

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents 3 element c.b.c.e.

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Physical equivalents 5 elements c.b.c.e. Early Giacoletto

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Problem Find the gain and the input resistance of the shown circuit! Input data:  = 200, U t = 12 V, U B =6 V, I E = 1 mA, current in the voltage divider at the base: 0,1 mA. In Out  k mA V RR BB   k I U R E B E     

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET u out out Input VmA V U I U I g T E T C m / 

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET u out Input in

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Considering the capacitances T 0 is the base transit time

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Considering the capacitances

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Two port parameters E.g.: h parameters (hybrid parameters) Different convention for reference directions!

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Two port parameters h parameters constUu dI i i h   current gain in case of shorted output constIi dU dI u i h   output conductance in case of open input constIi dU u u h   voltage backlash in case of open input constUu dI dU i u h   input resistance when the output is in short

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Two port parameters h parameters, c.e., c.b.:

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Two port parameters h parameters on data sheets

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET High frequency operation

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET High frequency operation cut-off frequencies of the BJT 20 db/decade meas

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET High frequency operation cut-off frequencies of the BJT

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET High frequency operation cut-off frequencies of the BJT

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET The BJT as a power switch

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Switching mode operation The BJT as a power switch Two stable op.points: closed (A), saturated (B) Important question: the power to be switched? saturation

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Switching mode operation The BJT as a digital signal processing device Two stable op.points: closed / saturated Transfer characteristic: inverter-like Important question: how quick is the switching? out in

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Maximal ratings P dmax dissipation hyperbole can be exceeded for short time

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Switching transients Two types: inner and outer transients Only the inner transients will be discussed out in in1 in0 in2

Budapest University of Technology and Economics Department of Electron Devices Microelectronics BSc course, Bipolar transistor 4 © András Poppe & Vladimír Székely, BME-EET Switching transients out in in1 in0in2 IN IN1 IN0 in0