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本帖最后由 致橡树 于 2010-7-20 23:13 编辑
An Amorphous-Silicon Operational Amplifier and Its
Application to a 4-Bit Digital-to-Analog Converter
Yi-Chuan Tarn, Po-Chih Ku, Hsieh-Hung Hsieh, and Liang-Hung Lu
Abstract—A circuit topology suitable for the implementation of
operational amplifiers (OPAMPs) in an amorphous-silicon (a-Si)
thin-film-transistor (TFT) technology is presented in this paper.
Due to the use of a positive feedback in the input differential pair,
the gain of the OPAMP is effectively boosted, facilitating analog
circuit designs for system-on-panel (SoP) applications. Based on
the proposed technique, a 4-bit digital-to-analog converter (DAC)
prototype, which consists of a resistor string and a unity-gain
buffer, is developed. The DAC is implemented by using an 8- m
a-Si NTFT process. Operated at a supply voltage of 25 V, the
fabricated circuit consumes a dc power of 3.68 mW. For an output
voltage range from 9.5 to 12.5 V, the measurement results indicate
a differential non-linearity (DNL) of 0.216 LSB and an integral
non-linearity (INL) of 0.667 LSB. With a settling time less than
1.1 ms, the DAC circuit can operate at a maximum conversion rate
of 0.9 kS/s.
Index Terms—Amorphous silicon (a-Si), digital-to-analog converters
(DACs), operational amplifiers (OPAMPs), positive feedback,
resistor string, thin-film transistors, unity-gain buffer. |
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