公开(公告)号：US10024153B2

公开(公告)日：2018-07-17

申请号：US15104610

申请日：2013-12-16

申请人： Sondex Wireline Limited

发明人： Kenneth Tomkins

IPC分类号： E21B47/00 ,  E21B49/08 ,  E21B49/00 ,  E21B47/01 ,  G11C27/02 ,  G01V11/00 ,  E21B47/06

摘要： A peak hold circuit configured for use in a downhole sensor includes a long tail pair circuit, a correction circuit, and a current mirror circuit. The current mirror circuit includes two current mirrors connected to a long tail pair formed by a first transistor and a second transistor. The current mirror also includes a first resistor and a second resistor connected to a third transistor. The first transistor is connected to a correction transistor of the correction circuit. The value of the first resistor is selected to be essentially equal to the same value as the second resistor so that when the long tail pair is balanced, the current flowing through a collector of the second transistor is equal to the current flowing through the first transistor, causing the correction transistor to switch off.