| 摘要 |
<p>An integrated circuit generates a constant reference voltage Vref independent of ambient temperature or semiconductor device fabrication process variations. A countering circuit is included to adaptively counter for any deviations caused in a bandgap reference voltage. In an embodiment, a current, proportionate to deviation of Vbe from a nominal value, is injected into an emitter-base junction to cause Vbe to equal a nominal value. Amplifier 350 maintains nodes 351, 352 at the same potential (virtual short) due to negative feedback action. Therefore this causes a current proportional to the difference between the base-emitter voltages of bipolar transistors 315, 316 to flow through resistors 321, 322, 323, 324. This current is proportional-to-absolute-temperature (PTAT) current which causes a voltage drop (across these resistors) proportional to the absolute temperature. The voltage Vref, being the sum of voltage drop across resistors 323, 324 and Vbe of transistor 316 is therefore invariant to changes in temperature. The PTAT term, being proportional to the difference (Vbel-Vbe2), is invariant with process.</p> |
