Download UC Berkeley EECS 105 Spring '92 Final - Bipolar Transistor & Op-Amp Problems and more Exams Microelectronic Circuits in PDF only on Docsity!
University of California at Berkeley
College of Engineering
Department of Electrical Engineering
and Computer Sciences
EECS 105, Spring/
Final Examination
professor R.t.Howe
Default bipolar transistor parameters: npn: !!1! data
Default MoOS transistor parameters: NMOS: !!!! data PMOS: !!!! data
Problem #1 Device Physics[20 points]
Given: Rather than the default parameters on the cover sheet, the above bipolar transistor has the following properties:
Current gain: !!!(Bata)= Base-collector capacitance: !!!!(data), where the collector-base voltage is in volts Base transit time: !!!(data) The capacitors C1,C2, and !!!(CE) and all blocking capacitors.
(a) [4 points] Find the numerical value of !!!() for the DX operating point defined in the circuit above.
(b) [4 points] The cross section of the transistor at the operating point found in part(a) is shown below. The base-emitter depletion width is one-fourth the base-collector deplention width. Find the numerical value of !!!() for the circut above.
(c) [4 points] Find the numerical value of the Miller capacitor !!(CM) for this inverting amplifier, along with the numerical value of its comer(-3 dB) frequency,fc.
(d) [4 points] The circuit is modified by reducing the voltage supply to the collector from 6V to 3V, as shown in the schematic below. Note that the voltage supply to the base is left unchanged. What is the numerical value of !!!()? Accurately sketch the new base-collector depletion width on the cross section.
(e) [4 point] For the modified circuit in part (d), find the numerical value of the Miller capacitor !!!(CM), along with the numerical value of its comer(-3 dB) frequency,fc.
University of California at Berkeley College of Engineering Department of Electrical Engineering and Computer Scien 1
Problem #2. Differential Amplifier [20 point]
(a) [4 point] What is the numerical value of the DC collector current in Q1? You cna use the average value of the two input voltages to find Ic1.
(b) [4 point] What is the small-signal differential half-circuit for this amplifier? What is the numerical value of the differential gain, ad?
(c) [4 point] What is the small-signal common-mode half-circuit for this amplifier? What is the numerical value of the common-mode gain, ac?
(d) [4 point] What is the numerical value of the total output voltage, !!(vo1)? Note : the error band is not 10% for this part -- use both the bias and small-signal models to arrive at your answer.
(e) [4 point] What is the numerical value of the total output voltage, !!(vo2)? Note : the error band is not 10% for this part -- use both the bias and small-signal models to arrive at your answer.
Problem #3. Single-ended Amplifier with Active Load [20 point]
(a) [4 points] What are the collector currents in all transistors? Verify that all are forward active, assuming that Vo=2V.
(b) [4 points] What are the maximum and minimum values of the output voltage, V., such that all transistors are forward active?
(c) [4 points] What is the numerical value of the input resistance, Ri?
(d) [4 points] What is the numerical value of the output resistance, Ro?
(e) [4 points] What is the numerical value of the small-signal voltage gain,Vo/Vs?
Problem #4."NMOS with PMOS load" Logic Gate [20 point]
(W/L) is given next to each transistor label; use the default NMOS and PMOS parameters. for each device, the body is shorted to the source (connection not shown).
(a) [4 points] What is the numerical value of the drain current !!!(data) of device M2? Hint: both M1 and M are diode-connected and have identical geometries.
(b) [4 points] For the case where VB = 0 V, plot the load line of device ML on the output characteristices of device MA, which are given below.
(c) [4 points] Plot the out put voltage Vo as a function of the input voltage VA on the graph below. You can
Problem #2. Differential Amplifier [20 point] 2
(g) [3 points] Find the -3 dB frequency for this op amp. You can neglect the contribution of !!data in your calculations.
Posted by HKN (Electrical Engineering and Computer Science Honor Society)
University of California at Berkeley
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Problem #5. Bipolar operational amplifier [20 point] 4
