Citation: |
Lai Xinquan, Li Xinlin, Ye Qiang, Yuan Bing, Li Xianrui. A constant-gm and high-slew-rate operational amplifier for an LCD driver[J]. Journal of Semiconductors, 2009, 30(12): 125002. doi: 10.1088/1674-4926/30/12/125002
Lai X Q, Li X L, Ye Q, Yuan B, Li X R. A constant-gm and high-slew-rate operational amplifier for an LCD driver[J]. J. Semicond., 2009, 30(12): 125002. doi: 10.1088/1674-4926/30/12/125002.
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A constant-gm and high-slew-rate operational amplifier for an LCD driver
doi: 10.1088/1674-4926/30/12/125002
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Abstract
To drive the backplane of a liquid crystal display device and achieve different kinds of grey levels, a high-slew-rate operational amplifier with constant-gm input stage is presented. A Zener-diode structure is inserted between the tails of the complementary input pairs to keep the gm of the input stage constant. A novel slew rate enhancement circuit is implemented to achieve a very high slew rate. The chip has been implemented in a 0.5 μm CMOS process and the chip area of the operational amplifier circuit is 0.11 mm2. The testing results indicate that in the 5–8 V input range, the maximum gm fluctuation is only 4.2%. The result exhibits a high slew rate of 111 V/ s and 102 V/ s for the rising and falling edges under a 20 pF capacitance load, and the low frequency gain is up to 109 dB with a phase margin of 70 ℃.-
Keywords:
- constant-gm,
- operational amplifier,
- Zener diode,
- slew rate
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References
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Proportional views