| CPC G01J 1/4204 (2013.01) [G01J 1/44 (2013.01); G01J 2001/446 (2013.01); H03F 3/45071 (2013.01); H03F 2200/375 (2013.01)] | 19 Claims |

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1. A circuit comprising:
an operational amplifier;
a first capacitor having a first electrode coupled to an inverting input of the operational amplifier and a second electrode coupled to a non-inverting output of the operational amplifier;
a compensation circuit coupled between the operational amplifier and the first capacitor; and
a preset circuit comprising:
an input coupled to a first voltage node;
an output coupled to the first capacitor, the first voltage node configured to carry a first voltage equal to a preset voltage multiplied by a coefficient;
a second capacitor having a capacitance equal to a capacitance of the first capacitor divided by the coefficient;
a third capacitor having a capacitance smaller than the capacitance of the first capacitor; and
a fourth capacitor having a capacitance equal to the capacitance of the third capacitor divided by the coefficient.
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