A rail-to-rail op-amp with high stability over temperature variation at 1-V supply voltage is presented in this thesis. It incorporates a modified CM adapter and a modified bandgap reference. First, the modified CM adapter utilizes a level-shifting technique to shift the input common mode voltage of 0-1 V to the level below 0.1 V. By introducing this circuit as the front-end block of the proposed op-amp, the PMOS differential input stage can be operated appropriately with the rail-to-rail input common mode range. Second, the modified bandgap reference that combines two voltages with opposite temperature coefficients generates a temperature-insensitive bias current to the input stage. Besides, by the technique of cascading a diode with an additional BJT, the junction area of the original diodes can be reduced and in the actual application, fewer parallel-connected BJTs are needed.
The two circuits are applied to the proposed op-amp operated at 1-V supply voltage in TSMC 1P4M 0.35£gm CMOS technology. At 25¢J, the dc gain is 78.9 dB and unity-gain bandwidth is 3.73 MHz. The phase margin is 42.9¢X. For the temperature from 0¢J to 75¢J, the frequency response is temperature-insensitive and the dc gain variation is 2dB. The layout view of the proposed op-amp is also presented and the area is 0.2 mm2.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0621102-201457 |
| Date | 21 June 2002 |
| Creators | Hong, Ming-Hwa |
| Contributors | Chia-Hsiung Kao, Jinn-Shyan Wang, Jyi-Tsong Lin |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0621102-201457 |
| Rights | not_available, Copyright information available at source archive |
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