| Summary: | 碩士 === 中原大學 === 電機工程研究所 === 94 === Due to the difficulty to precisely fabricate the capacitance in integrated circuits, it becomes an important research work to find a tunable element for the replacement of the capacitor used to realize the s terms in transfer function. The input-and-output relationship of an Operational Amplifier (OA) is show as below.
In which A0 is the gain, ω0 the bandwidth, and B0 the product of both gain and bandwidth. It is exhibited that an OA can also be used to realize the s terms in transfer functions. We have found that the B0 is variable tuning either the bias current or the inner compensation capacitance of an OA just like the variation of the transconductance of an OTA through the tuning of its bias current. Therefore, the capacitor with error fabricated in the integrator circuit can be replaced by the OA tunable through its inner bias current.
The thesis is focused on the design of biquads using both tunable OAs and tunable OTAs, leading to produce precise output responses such as Low-pass、Band-pass and Notch filtering signals, Finally, the H-spice simulation with 0.35μm process verifies the theoretical predictions.
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