Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Patent
1998-03-24
1999-12-14
Cunningham, Terry D.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
327538, 327539, 323313, G05F 110
Patent
active
060022930
ABSTRACT:
A high transconductance voltage reference cell produces a large change in output current for a very small change in input voltage near a settable equilibrium point, which can be made equal to two bandgap voltages, or to non-integer multiples of the bandgap voltage without the use of a resistive divider. A first and second pair of bipolar transistors, at least one of which have unequal emitter areas, are arranged in a crossed-quad configuration, with a first resistor interposed between one of the first pair and second pair transistors and a second resistor interposed between one of the second pairs' emitters and a common point. For input voltages below the equilibrium point, most of the current through the cell flows down one side of the quad. The voltage drop across the first resistor increases with input voltage, and causes the cell current to be abruptly switched from one side of the quad to the other at the equilibrium point. This large change in current induced by a small change in input voltage provides the cell's high transconductance. The cell can be made to exhibit a lower g.sub.m or some hysteresis by adjusting the relationship between the resistor values. The equilibrium point is dictated by the emitter area ratios between the quad's transistors, which cause the cell to carry a proportional-to-absolute-temperature (PTAT) current at the equilibrium point. The PTAT current can be made to compensate the quad to provide a temperature invariant equilibrium point.
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A. Paul Brokaw, "A Simple Three-Terminal IC Bandgap Reference", IEEE Journal of Solid-State Circuits, vol. SC-9, No. 6, Dec. 1974, pp. 30b-35b.
Analog Devices Inc.
Cunningham Terry D.
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