Super-gain transistors for IC´s

Transistors with current gains of 2000 to 10000 at collector currents less than 1 μA can now be made in monolithic circuits. This is more than ten times the gain of present-day discrete transistors. The significance of this breakthrough is greatest for IC operational amplifiers as lower input bias currents are constantly being sought. Circuit techniques are available, namely bootstrapping and cascade connections, that take advantage of the high-current gain of one transistor type and the high-breakdown voltage of the second, producing the equivalent of a high gain, high-voltage device. This may double the number of transistors needed to perform a given function, but it is an economical approach for monolithic IC´s as active devices have a relatively low cost.