A delay circuit includes a first and a second switching transistor, each of which has a control electrode and a first and a second main electrode, a first and a second input of the delay circuit being coupled to the control electrode of the first switching transistor and the second switching transistor,...http://www.google.de/patents/US5477182?utm_source=gb-gplus-sharePatent US5477182 - Delay circuit for delaying differential signals includes separately controllable first and second load and clamp circuits for effecting different delay times
