BME 140 Instructor: Design of Biomedical Electronics Professor Zhongping Chen Homework Problem Set III Due: Tuesday, January 28, 2020 (before lecture) Suggested Readings: Chapter 3 of the textbook, and supplemental readings 1 and 4 on the web. 1. Using ideal-op-amp assumption, (a) Find the currents labeled in the following inverting amplifier. (b) What is the output voltage vo and gain Av ? 2. A circuit known as summer is shown in the following figure. (a): Use ideal-op-amp assumption to solve for the output voltage in terms of the input voltages and resistor values. (b): What is the input resistance seen by v ? (c): What is the input resistance seen by v ? (d): What is the output resistance seen by the load RL A B 1 1/17/20 3. Using ideal-op-amp assumption, find an expression for the output voltage of the circuit. 30 kΩ 15 kΩ 4. Problem 3.1 on page 123 of the text book 5. The following figure shows an inverting amplifier that can have high gain without resorting to as wide a range of resistor values as are needed in standard inverter configuration. (a): Shown that the voltage gain under the ideal-op-amp assumption is given by the following equation: Av = &R vo R RR # = −$$ 2 + 4 + 2 4 !! vin % R1 R1 R1R3 " (b): Evaluating the gain if the resistor values are: R1=R3= 1 kΩ. R2=R4=10 kΩ. (c): if R1=R3= 1 kΩ. R2=R4=10 kΩ, Compare to the regular inverting amplifier in Problem 1, which amplifier has high gain? 2 1/17/20