Patent ID: 6323700
Filing Date: 2001-11-27
Classification: G11C

Abstract:
Input buffer for a switched emitter follower track-and-hold amplifier comprising an input stage with an input transistor (Q1), a first diode (Q2, Q2b), a cathode side of which first diode (Q2, Q2b) is connected to an emitter of the input transistor (Q1), a first current source (4) between on the one hand the junction between the cathode of the first diode (Q2, Q2b) and the emitter of the input transistor (Q1) and on the other hand a first supply voltage line (2), an anode of the first diode (Q2, Q2b) being connected to a track-and-hold controlled emitter follower (6), characterised in that the first current source (4) is a non-switched constant current source, in that a second current source (M1) is connected between a collector of the input transistor (Q1) and a second supply voltage (3), in that a second transistor (M2, M2b) comprising a control electrode, a current input electrode and a current output electrode is connected with the control electrode to the junction (n1) between the collector of the input transistor (Q1) and the second current source (M1), with the current input electrode to the second supply voltage (3) and with the current output electrode to the anode of the first diode (Q2), in that a second diode (Q2a) is connected with a cathode to the junction between the cathode of the first diode (Q2b) and the emitter of the input transistor (Q1), and in that a third transistor (M2a) comprising a control electrode, a current input electrode and a current output electrode is connected with the control electrode to the junction (n1) between the collector of the input transistor (Q1) and the second current source (M1), with the current input electrode to the second supply voltage (3) and with the current output electrode to the anode of the second diode (Q2a).