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US 2003/0164730 A1Published application
High duty cycle offset compensation for operational amplifiers
AssigneeKoninklijke Philips Electronics N.V.
InventorAndrea Milanesi
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AssigneeKoninklijke Philips Electronics N.V.
InventorAndrea Milanesi
Estimating the term…
A circuit arrangement comprising an input amplifier stage (31) with two inputs (36, 37) and an output (34) being connectable to an input (35) of an output amplifier stage (32). The circuit furthermore comprises a comparator (33) with a first input (41), a second input (42) and a comparator output (44), a feedback capacitor (43) connected to an offset tuning input (45) of the input amplifier stage (31), and a plurality of switches (S1, S2) that are controllable by switching signals (V1, V2) to allow the circuit to be switched from a first phase to a second phase. During the first phase (1), the output (34) and the input (35) are separated by a first one of the switches (S2) and the two inputs (36, 37) are connected via a second one of the switches (S1). The first input (41) of the comparator (33) is connected to the output (34) of the input amplifier stage (31) and the second input (42) of the comparator (33) is connected to the input (35) of the output amplifier stage (32) such that via the comparator output (44) a charge on the feedback capacitor (43), and hence the voltage at the offset tuning input (45) is altered and an offset of the input amplifier stage (31) is corrected.
A circuit arrangement comprising an input amplifier stage (31) with two inputs (36, 37) and an output (34) being connectable to an input (35) of an output amplifier stage (32), a comparator (33) with a first input (41), a second input (42) and a comparator output (44), a feedback capacitor (43) connected to an offset tuning input (45) of the input amplifier stage (31), and a plurality of switches (S1, S2) that are controllable by switching signals (V1, V2) to allow the circuit arrangement to be switched from a first phase to a second phase, wherein during the first phase,
A circuit arrangement as claimed in one of the preceding claims, wherein the output amplifier stage (32) comprises an amplifier (38), preferably an operational amplifier, whose output (40) is connected in a feedback fashion, via a compensation capacitor (39), to the input (35) of the output amplifier stage (32).
A circuit arrangement as claimed in one of the preceding claims, wherein the output (40) of the amplifier (38) is connectable to a load.
A circuit arrangement as claimed in one of the preceding claims, wherein the output (40) of the amplifier (38) is intrinsically stable.
A circuit arrangement as claimed in one of the preceding claims, wherein the comparator (33) generates a current at the output (44) if there is a voltage difference between the first input (41) of the comparator (33) and the second input (42) of the comparator (33).
A circuit arrangement as claimed in one of the preceding claims, wherein the input amplifier stage (31) is realized in a mirrored topology.
A circuit arrangement as claimed in one of the preceding claims, wherein the output amplifier stage (32) is realized in an AB-topology or in an A-topology.
A circuit arrangement as claimed in one of the preceding claims, wherein the comparator (33) is realized as a differential stage.
A method for compensating the offset voltage of an input amplifier stage (31) with two inputs (36, 37) and an output (34), the input amplifier stage (31) being part of a circuit arrangement comprising
Dependencies are inferred from the claim text.