| Summary: | 碩士 === 明新科技大學 === 積體電路佈局產業碩士專班 === 106 === With the progress of e-generation technology, electronic products, which people use today, need a variety of functions. In order to cover much complex operating system, circuit design is also much complicated. Pre-simulation results of circuit are good firstly. However, the measurement of circuit is not predictable after circuit tape out. There are many factors influencing circuit performance. Layout plan is the key point. Because circuit, layout and process are correlated, cautious layout plan can reduce interference and parasitic effect within signals.
In recent technology field, operational amplifier are widely used and thus developed to many types, whose characteristics is unique. Therefore, if we want to understand the family of operational amplifier, we should be able to analyze internal circuit of operational amplifier, basic property and its functionality. The characteristics of ideal operational amplifier are as follows : (1) Infinity input impedance (2) Zero output impedance (3) Infinite open loop voltage gain (4) Infinite bandwidth (5) Zero input offset voltage (6) Infinite CMRR (Common mode rejection ratio) (7) Zero transient response.
In this paper, operational amplifier is implemented on CIC 0.18μm CMOS process, The architecture of operational amplifier is folded-cascode. Comparing with traditional differential and cascode amplifier, open loop gain and input voltage range of signal is larger in folded-cascode amplifier.
At the end of this paper, we will discuss that how layout symmetry has influence on the performance of operational amplifier. It can be seen that symmetric layout plan is much better than non-symmetric layout. It is also evident that the parasitic resistance and capacitance, which is non-ideal effect, is small. We can conclude that layout symmetry plays an important rule in operational amplifier design.
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