| 摘要 |
PURPOSE:To provide a band gap type constant voltage circuit built in an ECL circuit and allowed to be stably driven even at voltage less than external power supply voltage 3V. CONSTITUTION:A potential difference between nodes 1, 2 in a band gap part 3 is detected by an operational amplifier 4 and fed back to the nodes 1, 2 so as to eliminate the difference. When voltage between the base and emitter of a transistor(TR) Q1 is defined as Vbe1, output voltage Vcs to be supplied to the ECL circuit is Vcs= Vbe1+Vo. The positive and negative temperature coefficients of a bipolar circuit part are offset by selecting an R1/R2 ratio and a required voltage Vo fixed against a change in temperature and a change in external power supply voltage is outputted by selecting R3. The lower limit of the external power supply voltage by which a constant voltage circuit is normally driven is applied by a voltage range in which the amplifier 4 can be operated, and when the circuit 4 is constituted of a CMOS circuit, the operation voltage can be dropped down to about 1.3V. |
