Latvian Patent No. 14641 “Equivalent time sampling convertor of comparator type” inventors: K.Krūmiņš, E.Beiners, V.Pētersons. Owners: Institute of Electronics and Computer Science. Published: 20.02.2013.
The invention relates to measuring technique, and it can be used for sampling conversion of electrical signals. Invention aims to improve performance of sampling converter being of comparator type, which is built on clocked comparator; in particular the invention aims to get converter “zero” level permanence of signal to be converted for connected or disconnected signal source with an arbitrary internal resistance. To achieve this goal clocked comparator’s 1 signal input 2 is connected to the “zero” level shift compensation resistor 7, and the resistor’s second output is connected to the direct voltage source 8, which is set at a voltage such that the connecting or disconnecting of the source signal being converted with an arbitrary internal resistance do not change the “zero” level of the converter output.
http://www.lrpv.gov.lv/sites/default/files/media/vestnesis/20130220.pdf