| 摘要 |
A circuit for use in a current source or a proportional to absolute temperature (PTAT) sensor or in a bandgap regulator comprises a PTAT cell having two parallel current branches each including at least one transistor and at least one resistor, and a control circuit for determining the relationship between the driving currents through the two branches. Transistor QND in the first branch has a higher effective current density than that of a second transistor QNW in the second branch so as to develop control voltages (VBE) across the first and second transistors whose difference ( W VBE) is regulated by the voltage across a regulating resistor RNW in the second branch. A further regulating resistor RPW is provided in the first branch, the voltage drop across which regulates the effective difference in current densities between a third transistor QPW and a reference transistor. Substantially the whole of at least one W VBE voltage is developed across a regulating resistor or resistors in each of the two branches for each full VBE of potential that is needed to bias the circuit into its operating condition. The reference transistor may either be the first transistor (fig 7, QD) or a fourth transistor QPD, and may use opposite polarity transistors. The transistors may be bipolar types or field effect transisitors (FET). Currents in both branches generate voltages across the regulating resistors which allow an improved signal to noise ratio for the circuit. |
