Wide band-width operational amplifier
First Claim
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1. A differential operational amplifier circuit comprising:
- a first operational amplifier (opamp) having a differential pair of input terminals receiving a differential input signal, and a differential pair of output terminals;
a first resistor-capacitor frequency compensation network coupled to said first operational amplifier;
a second operational amplifier (opamp) having a differential pair of input terminals coupled to said differential pair of output terminals of said first opamp, and a differential pair of output terminals;
a second resistor-capacitor frequency compensation network coupled to said second operational amplifier; and
a feed-forward circuit having a differential pair of input terminals coupled to said differential pair of input terminals of said first opamp, and a differential pair of output terminals coupled to said second opamp,wherein, said differential input signal bypasses said first opamp through said feed-forward circuit at a selected frequency, andwherein, the differential operational amplifier has substantial DC gain.
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Abstract
Various circuit techniques to implement continuous-time filters with improved performance are disclosed. The present invention uses RMC type integrators that exhibit lower harmonic distortion. In one embodiment, a novel high-gain two-pole operational amplifier is used along with RMC architecture to achieve lower harmonic distortion. In another embodiment, the present invention uses dummy polysilicon resistors to accurately compensate for the distributed parasitics of the polysilicon resistors used in RMC integrator. In yet another embodiment, the present invention provides an on-chip tuner with a differential architecture for better noise immunity.
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Citations
12 Claims
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1. A differential operational amplifier circuit comprising:
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a first operational amplifier (opamp) having a differential pair of input terminals receiving a differential input signal, and a differential pair of output terminals; a first resistor-capacitor frequency compensation network coupled to said first operational amplifier; a second operational amplifier (opamp) having a differential pair of input terminals coupled to said differential pair of output terminals of said first opamp, and a differential pair of output terminals; a second resistor-capacitor frequency compensation network coupled to said second operational amplifier; and a feed-forward circuit having a differential pair of input terminals coupled to said differential pair of input terminals of said first opamp, and a differential pair of output terminals coupled to said second opamp, wherein, said differential input signal bypasses said first opamp through said feed-forward circuit at a selected frequency, and wherein, the differential operational amplifier has substantial DC gain. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A differential amplifier circuit comprising:
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a first operational amplifier (opamp) having a differential pair of input terminals receiving a differential input signal, and a differential pair of output terminals; a second operational amplifier (opamp) having a differential pair of input terminals coupled to said differential pair of output terminals of said first opamp, and a differential pair of output terminals; and a feed-forward circuit having a differential pair of input terminals coupled to said differential pair of input terminals of said first opamp, and a differential pair of output terminals coupled to said second opamp, wherein, said differential input signal bypasses said first opamp through said feed-forward circuit at a selected frequency, and wherein each one of said first opamp and said second opamp comprises a folded cascode CMOS operational amplifier comprising; a first differential pair input stage; a class A/B second gain stage coupled to said first differential pair input stage; and a common-mode feedback circuit coupled to a pair of differential output terminals of said second gain stage, wherein, said folded cascode CMOS operational amplifier has a single dominant pole.
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Specification