Dual collector transistor, used in two output integrated injection logic gates.

Integrated injection logic is one of the few digital logic families that uses current signaling rather than voltage signaling.

The HBT can be used in integrated injection logic (IL).

Integrated injection logic (I2L)

The integrated injection logic (IIL or IL) uses bipolar transistors in a current-steering arrangement to implement logic functions.

Integrated injection logic (IIL, IL, or I2L) is a class of digital circuits built with multiple collector bipolar junction transistors (BJT).

In 1979, HP introduced a frequency measurement instrument based on a HP-made custom LSI chip that uses integrated injection logic (I2L) for low power consumption and high density, enabling portable battery operation, and also some emitter function logic (EFL) circuits where high speed is needed.

It is sometimes also known as merged transistor logic.

Together with Horst H. Berger, Wiedmann received the 1977 IEEE Morris N. Liebmann Memorial Award "for the invention and exploration of the Merged Transistor Logic, MTL".