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US 10,305,502 B2Granted
Complementary current reusing preamp for operational amplifier
AssigneeTexas Instruments Incorporated
InventorTien-Ling Hsieh
Life of this patent
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Abstract
An apparatus includes a preamplifier stage to receive a power supply voltage and generate an output based upon an input. In particular, the preamplifier stage includes a biasing device coupled between the output and a ground node to bias a DC voltage level of the output independently of the power supply voltage. The preamplifier stage also includes a complementary circuit to receive the input and generate the output. The complementary circuit reuses a current through the preamplifier stage to provide an increased transconductance of the preamplifier stage for a given current level.
Claims6
An apparatus comprising:
- a preamplifier stage including:
- an output;
- a current source;
- a PMOS differential pair coupled to a power supply side of the preamplifier stage, sources of the PMOS differential pair being coupled to the current source;
- an NMOS differential pair coupled to a ground side of the preamplifier stage, drains of the NMOS differential pair being coupled to respective drains of the PMOS differential pair at the output;
- a diode-connected device coupled to the output and ground;
- and
- a cross-coupled circuit coupled to the diode-connected device to adjust a gain of the preamplifier stage;
- wherein in the gain of the preamplifier is given by a ratio of a transconductance of the PMOS differential pair and the NMOS differential pair to a transconductance of the diode-connected device divided by N−1 where N is a ratio of size of the diode-connected device to the cross-coupled circuit.
6 more elements
Dependencies are inferred from the claim text.