Emitter-coupled logic circuit

摘要

The circuit has an output device with an output terminal (3), an emitter follower transistor (16) which connects emitter to output terminal, and load resistor (12) connected between output terminal and a potential. A differential amplifier (14,15) receives input signal and reference potential. Depending on whether the level of the input signal is greater than the reference potential or not, the output device charges a parasitic capacitor (13) in the output device such that the output signal goes to a high state, or discharges the parasitic capacitor by means of the load resistor to the potential such that the output signal goes to its low state. The ECL circuit also has a discharge device (20). This has one terminal connected to the output device. The other terminal is connected to a negative potential. The discharge device can be switched to its conductive state in response to an applied control signal such that the charge in the parasitic capacitor is discharged by means of the discharge circuit at the negative potential and also by means of the load resistor when the output signal goes from high to low.