Temperature compensated reference circuit

摘要

A compensated current reference circuit (10) includes bipolar transistors (32, 48) which have corresponding base-to-emitter resistors (36, 52). A bipolar transistor (70) and associated circuitry produces a variable amplitude tail current which has a predetermined temperature coefficient and regulates the current flow through the bipolar transistors (32, 48). The combination of tail current for the transistor (48) and the impedance size of its corresponding resistor (52) are adjusted to produce a reference current through a transistor (44) which has a relatively large negative temperature coefficient. The bipolar transistor (32) and its associated base-to-emitter resistor (36) together with the tail current through transistor (38) are adjusted such that a current through transistor (22) is produced which has a relatively small negative temperature coefficient. The difference of these currents is produced through a transistor (18) to produce a reference current having a relatively small controlled temperature coefficient. The control voltage at node (96) is provided to a transistor (81) to produce a stable reference current therethrough. The selection of appropriate values for tail currents and the base-to-emitter resistor impedances for the bipolar transistors (32, 48) can produce any of a wide range of values of temperature compensated currents. The reference currents are also mirrored to a node (100) and summed to produce an output current having a desired temperature coefficient which is in turn passed through a resistor (116) to produce a temperature compensated voltage at a node (94).