Wide gain range and fine gain step programmable gain amplifier with single stage switched capacitor circuit
AssigneeNational Semiconductor Corporation
InventorBumha Lee
Life of this patent
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Abstract
The present invention is directed towards a single stage switched capacitor programmable gain amplifier. The operation of the amplifier is described by a transfer function having two gain factors: (C1/C2) and (C2/C3). The transfer function is equal to the product of the two gain factors: (C1/C2)×(C2/C3) such that the transfer function is equal to (C1/C3). The combination of the two different gain factors provides a wider range and finer step programmability of the amplifier. The amplifier does not have an idle phase, which reduces power dissipation. Additionally, the amplifier requires less switching which results in reducing the thermal noise and the switching noise produced by the amplifier.
Claims18
A switched capacitor programmable amplifier circuit, comprising:
- a first capacitor that is configured to store a sampled charge that is associated with an input signal during a sampling phase and transfer the sampled charge during a holding phase;
- a second capacitor that is configured to discharge during the sampling phase and provide a first capacitive feedback path such that a first amplified charge is stored on the second capacitor during the holding phase;
- a third capacitor that is configured to provide a second capacitive feedback path during the sampling phase and discharge during the holding phase;
- and
- an amplifier that is configured to amplify the transferred sampled charge using the first capacitive feedback path to produce the first amplified charge during the holding phase and amplify the stored first amplified charge using the second capacitive feedback path to produce a second amplified charge during the sampling phase.
A circuit for amplifying a signal, comprising:
- means for storing a sampled charge that is associated with an input signal during a sampling phase on a first capacitor;
- means for transferring the sampled charge from the first capacitor during the holding phase;
- means for providing a first capacitive feedback path through which a first amplified charge is stored on a second capacitor during the holding phase;
- means for providing a second capacitive feedback path during the sampling phase;
- means for amplifying the transferred sampled charge using the first capacitive feedback path to produce the first amplified charge during the holding phase;
- and
- means for amplifying the stored first amplified charge using the second capacitive feedback path to produce a second amplified charge during the sampling phase.
A method for amplifying a signal, comprising:
- storing a sampled charge that is associated with an input signal during a sampling phase on a first capacitor;
- transferring the sampled charge from the first capacitor during the holding phase;
- providing a first capacitive feedback path through which a first amplified charge is stored on a second capacitor during the holding phase;
- providing a second capacitive feedback path during the sampling phase;
- amplifying the transferred sampled charge using the first capacitive feedback path to produce the first amplified charge during the holding phase;
- and
- amplifying the stored first amplified charge using the second capacitive feedback path to produce a second amplified charge during the sampling phase.
Dependencies are inferred from the claim text.