Enhanced Voltage Step Waveform Generator
Original Publication Date: 1985-Nov-01
Included in the Prior Art Database: 2005-Feb-19
Published European Patent Application 0123745 describes a voltage step or staircase voltage waveform generator of the cup and bucket capacitor type for a CRT vertical timebase circuit in which a cup capacitor is alternately charged and discharged by an input pulse train and increments of charge are transported to a bucket capacitor by means of current mirrors. In the enhanced circuit disclosed, both the cup and bucket charging circuits are current mirror arrays which may be digitally switched to provide digital control of cup discharge current and bucket charging current. This enables the voltage step height to be selected digitally for the vertical timebase of a variable format CRT display and microprocessor-controlled display analog systems. The circuit described in European Patent Application 0123745 (see Figs.