assignment1

# assignment1 - take Ccbi=0 2 RL RL Io Vin Vin-Vout Vout-Rgen...

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ECE145C (undergrad grad)/ ECE218c: Problem set #1 Problem #1 a) gd C i R gs C gs m V g 1 V 2 V 2 I 1 I In the circuit above, we can write = 2 1 22 21 12 11 2 1 V V Y Y Y Y I I Please derive by hand expressions for the real and imaginary part of Yij. Using the approximation , these will come out to be linear and quadratic functions of frequency. Plot all 4 parameters. 1 2 2 2 << i gs R C ω b Repeat for the circuit below (omit the plots, just give the expressions). Use the approximation that . 1 2 2 2 << s gs R C 1

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gd C i R gs C gs m V g 1 V 2 V 2 I 1 I s R Problem 2 cbi C bb R be C ' ' e b m V g be R ex R + - ' ' e b V cbx C Above is a device model . Recall that f m depl be be g C C τ + = , . Let us take Cje=17 fF, beta=50, Ccbi=2.6 fF, Ccb_total=4.3 fF, Rbb=30 Ohms, Rex=6.67 Ohms, and tau_f=0.44 ps. Lets use this device model in circuit caclculations below. The transistor, incidentally, has 3 um^2 emitter area, has a peak 280 GHz ft and 376 GHz fmax, operates at a maximum of 2.3 mA/um^2 at Vce=0.7 volts. For Now, let us simplify the model by taking beta=infinity and Rex=0. Further, let us
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Unformatted text preview: take Ccbi=0 2 RL RL Io Vin+ Vin-Vout+ Vout-Rgen Rgen A) For Io=3 mA, IoRL=300 mV, Rgen=RL, please find the small signal voltage gain of the circuit and the small signal input impedance. Exploit symmetry. Use nodal analysis or MOTC to find the high frequency response (gain as a function of frequency) Under limiting conditions (one transistor on, other off, what is the maximum output voltage, and what approximate input voltage is required to obtain this). RL RL Ics RL RL Ics Ief Ief b) Multistage bipolar amplifiers tend often to look like the ckt on the left…lets take a one-stage slice of this, as in the next figure… 50 50 Vout+ Vout-RL RL Ics Ief Ief Vin+ 50 50 Vin-…based upon this, find the small-signal voltage gain Vout/Vin of this circuit at low frequencies. 3...
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## This note was uploaded on 08/06/2008 for the course ECE 145 taught by Professor Rodwell during the Fall '07 term at UCSB.

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assignment1 - take Ccbi=0 2 RL RL Io Vin Vin-Vout Vout-Rgen...

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