Charge amplifier with automatic zero
AssigneeFisher Controls International LLC
InventorRichard H. Pederson
Life of this patent
Estimating the term…
Abstract
A charge amplifier includes an operational amplifier having first and second voltage dividers across its output connected to a capacitor and a resistor, respectively, in an R-C network returned to one input for magnifying the apparent value of the impedance of the capacitor and of the resistance of the resistor. Its output is also connected to an integrating network including another operational amplifier having its output supplied to a third voltage divider supplying signal to another input of the first operational amplifier. A pair of differentially coupled piezoelectric charge sources supply signal to the amplifier through filters and the second voltage divider has a portion shunted by a parallel connection of back-to-back diodes and another resistor for effectively attenuating response to low frequency signals.
Claims13
A high gain amplifier for amplifying extremely small signals in a hostile environment that precludes use of large value resistors comprising:
- an operational amplifier of nominal characteristics and offset voltage having an output terminal and two input terminals;
- a resistance-capacitance network coupled between said output terminal and one of said input terminals;
- resistance magnification means for magnifying the apparent value of the resistance in said resistance-capacitance network;
- and
- feedback means for nullifying the effects of said resistance magnification means on said offset voltage of said operational amplifier.
A charge amplifier for amplifying extremely small signals in a hostile environment that precludes the use of large value resistors comprising;
- an operational amplifier of nominal characteristics and offset voltage having an output terminal and two input terminals;
- a resistance-capacitance network coupled between said output terminal and one of said input terminals;
- magnification means comprising a first voltage divider connected across the output terminal of said operational amplifier and connected to the resistance in said resistance-capacitance network for magnifying the apparent value of the resistance and a second voltage divider coupled across the output terminal of said operational amplifier and connected to the capacitance in said resistance-capacitance network for magnifying the impedance of the capacitance;
- and
- feedback means for nullifying the effects of said magnification means on said offset voltage of said operational amplifier, said feedback means including a third voltage divider connecting its output to the other of said input terminals of said operational amplifier, said magnification means enabling independent adjustment of the overshoot characteristics and cutoff frequency of said operational amplifier.
Dependencies are inferred from the claim text.