Double-cascode two-stage operational amplifier
AssigneeGlobespanVirata, Inc.
InventorRunhua Sun
Life of this patent
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Abstract
A two-stage op-amp circuit including a double-cascode telescopic op-amp circuit in the input stage and a fully-differential op-amp circuit in the output stage and having very high open-loop DC gain, very high unity-gain frequency, and relatively very low power consumption is presented. The input stage op-amp circuit and the output stage op-amp circuit are each comprised of a plurality of electrically connected MOSFET's. The input stage op-amp circuit provides very high gain, high input resistance, and large common mode rejection. The output stage op-amp circuit provides gain, low output resistance, and minimal output loss.
Claims6
An operational amplifier comprising:
- an input stage comprising a first plurality of metal-oxide semiconductor field-effect transistors electrically connected in a double-cascode telescopic operational amplifier configuration;
- a positive input electrically connected to the input stage;
- a negative input electrically connected to the input stage;
- a first series circuit comprising a first coupling resistor and a first coupling capacitor electrically connected to the input stage;
- a second series circuit comprising a second coupling resistor and a second coupling capacitor electrically connected to the input stage;
- an output stage electrically connected to the first series circuit and to the second series circuit comprising a second plurality of metal-oxide semiconductor field-effect transistors electrically connected in a fully-differential operational amplifier configuration;
- a positive output electrically connected to the output stage, wherein a first load capacitor is electrically connected to the positive output;
- a negative output electrically connected to the output stage, wherein a second load capacitor is electrically connected to the negative output;
- a first plurality of bias inputs electrically connected to the input stage;
- and
- a second plurality of bias inputs electrically connected to the input and output stages.
An operational amplifier comprising:
- an input stage comprising a first plurality of metal-oxide semiconductor field-effect transistors electrically connected in a double-cascode telescopic operational amplifier configuration;
- an output stage electrically coupled to the input stage and comprising a second plurality of metal-oxide semiconductor field-effect transistors electrically connected in a fully-differential operational amplifier configuration.
A method for providing an operational amplifier having a very high open-loop DC gain, a very high unity-gain frequency, and a relatively very low power consumption comprising the steps of:
- providing an input stage having very high gain, high input resistance, and large common mode rejection and comprising a first plurality of metal-oxide semiconductor field-effect transistors configured in a double-cascode telescopic operational amplifier configuration;
- and
- providing an output stage electrically coupled to the input stage having gain, low output resistance, and a minimal output loss characteristic and comprising a second plurality of metal-oxide semiconductor field-effect transistors configured in a fully-differential operational amplifier configuration.
Dependencies are inferred from the claim text.