US 9,813,035 B2
Gain enhancement using advanced correlated level shifting
Zhichao Tan, Wilmington, MA (US); Khiem Quang Nguyen, Tewksbury, MA (US); and Xiao Hong Du, Wilmington, MA (US)
Assigned to Analog Devices, Inc., Norwood, MA (US)
Filed by Analog Devices, Inc., Norwood, MA (US)
Filed on Nov. 2, 2015, as Appl. No. 14/930,186.
Prior Publication US 2017/0126189 A1, May 4, 2017
Int. Cl. H03F 1/02 (2006.01); H03G 1/00 (2006.01); H03F 3/00 (2006.01); H03F 3/45 (2006.01)
CPC H03G 1/0094 (2013.01) [H03F 3/005 (2013.01); H03F 3/45479 (2013.01); H03F 2200/153 (2013.01); H03F 2203/45156 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method for operating a switched capacitor circuit, wherein the switched capacitor circuit comprises (i) an amplifier circuit including an operational amplifier, at least one sampling capacitor, and at least one feedback capacitor, (ii) a plurality of level shifting capacitors and (iii) a switching circuit network including a plurality of switches, the method comprising:
selectively connecting, with the switching circuit network, the plurality of level shifting capacitors to the amplifier circuit in first and at least second, non-overlapping, level shifting phases;
controlling, through the switching circuit network, the amplifier circuit and the plurality of level shifting capacitors in a sampling phase and a non-overlapping, charging phase;
during the sampling phase, (i) the sampling capacitor samples an input voltage and (ii) the plurality of level shifting capacitors are reset; and
wherein, during the charging phase, (i) the sampling capacitor transfers a majority of its sampled charge to the feedback capacitor and (ii) the operational amplifier charges the plurality of level shifting capacitors.