Patent ID: 7518439

Claim:
An amplifier circuit ( 50 ) comprising: an operational amplifier ( 52 ) having an inverting input terminal ( 54 ), a non-inverting input terminal ( 56 ) receiving a common mode voltage and an output terminal ( 58 ) providing an output voltage; a first switch (S 1 ) connected between an input voltage ( 51 ) and a first node ( 62 ); a first capacitor (C 1 ) connected between the first node ( 62 ) and the inverting input terminal ( 54 ) of the operational amplifier ( 52 ); a second switch (S 5 ) connected between the inverting input terminal ( 54 ) and the output terminal ( 58 ) of the operational amplifier ( 52 ); a third switch (S 6 ) connected between a second node ( 65 ) and the output terminal ( 58 ) of the operational amplifier ( 52 ); and one or more capacitor subcircuits, each capacitor subcircuit ( 60 , 61 ) comprising: a fourth switch (S 2 , S 7 ) connected between a first connection terminal ( 62 , 64 ) and a third node ( 66 , 67 ); a fifth switch (S 3 , S 8 ) connected between the input voltage ( 51 ) and a second connection terminal ( 64 , 65 ); a second capacitor (C 2 , C 3 ) connected between the third node and the second connection terminal; and a sixth switch (S 4 , S 9 ) connected between the third node and the common mode voltage, wherein the one or more capacitor subcircuits are connected in series, the first connection terminal of a first capacitor subcircuit is connected to the first node and the second connection terminal of a last capacitor subcircuit is connected to the second node; and the second connection terminal of the other capacitor subcircuits is connected to the first connection terminal of the following capacitor subcircuit, wherein the first, second, fifth and sixth switches are driven by a first clock signal and the third and fourth switches are driven by the inverse of the first clock signal, and wherein first, second, fifth and sixth switches are closed during a sample phase while the third and fourth switches are closed during a hold phase.