Project Assignment: Operational Amplifier Design

Project Specifications:

• Design an operational amplifier capable of providing a voltage gain of at least 500 V/V to a load as small as Tx. The circuit will include a differential amplifier, and additional amplifier stages. The input voltage is considered to be differential, while the output voltage should be measured with respect to the ground.

• The DC voltage at the output should be offset to OV.

• You are only allowed to use resistors, Ws, and MOSEETs in your design. Do not use capacitors or Operational Amplifiers.

• Since 500 V/V is not a small gain, the amplifier may not work properly for a large peak-to-peak input. Determine what the maximum peak-to-peak input should be, based on your design.

Project Evaluation (read carefully):

Your design will be evaluated, in addition to achieving a gain as close as possible to the expected one and a DC voltage as close as possible to OV, on the number of elements used (resistors, transistors). A good design will make use of the smaller number of elements possible. At the same time, transistors are preferred over resistors. For example, a current steering circuit that uses four transistors and one resistor should be preferred over three resistors. Also, using active loads (current mirrors) instead of resistors at the collector or drain of the differential amplifier is preferable. In other words, avoid resistors as much as possible. You can use as many amplifier stages as you find necessary (differential and non-differential amplifier stages), but a small number of stages usually implies a small number of elements, which is desired. Your design will also be evaluated on the analysis done by the group to theoretically study how the gain and output DC voltage can be achieved. A design that is based only on a trial-and-error approach will not be given the same credit as one for which proper analysis has been performed.

Deliverables:

• A report that describes the project, discusses all steps taken to come up with the design (including excerpts of the analysis steps followed), and shows final results (including simulation results that results that confirm the amplifier's operation). The report should include all parts required in a regular lab report.

• The actual working circuit built on a breadboard.

• Demonstrating that the circuit can be used as an opamp, but using negative feedback (inverting or non-inverting configuration).