LM194/LM394 Supermatch Pair
General Description
The LM194 and LM394 are junction isolated ultra wellmatched monolithic NPN transistor pairs with an order of
magnitude improvement in matching over conventional transistor pairs. This was accomplished by advanced linear processing and a unique new device structure.
Electrical characteristics of these devices such as drift versus initial offset voltage, noise, and the exponential relationship of base-emitter voltage to collector current closely approach those of a theoretical transistor. Extrinsic emitter
and base resistances are much lower than presently available pairs, either monolithic or discrete, giving extremely low
noise and theoretical operation over a wide current range.
Most parameters are guaranteed over a current range of
1 mA to 1 mA and 0V up to 40V collector-base voltage,
ensuring superior performance in nearly all applications.
To guarantee long term stability of matching parameters,
internal clamp diodes have been added across the emitterbase junction of each transistor. These prevent degradation
due to reverse biased emitter currentÐthe most common
cause of field failures in matched devices. The parasitic isolation junction formed by the diodes also clamps the substrate region to the most negative emitter to ensure complete isolation between devices.
The LM194 and LM394 will provide a considerable improvement in performance in most applications requiring a closely matched transistor pair. In many cases, trimming can be
eliminated entirely, improving reliability and decreasing
costs. Additionally, the low noise and high gain make this
device attractive even where matching is not critical.
The LM194 and LM394/LM394B/LM394C are available in
an isolated header 6-lead TO-5 metal can package. The
LM394/LM394B/LM394C are available in an 8-pin plastic
dual-in-line package. The LM194 is identical to the LM394
except for tighter electrical specifications and wider temperature range. Features …