Baseband noise reduction
First Claim
1. An active circuit, comprising:
- a first chopper circuit that receives an input signal and a chopping signal of a frequency higher than a base band of the input signal, and that provides a modulated input signal;
an amplifier that receives the modulated input signal and that provides an amplified signal resulting form amplifying the modulated input signal; and
a second chopper circuit that receives the amplified signal and the chopping signal to provide an output signal;
whereinthe first chopper circuit and the second chopper circuit further comprise a first switch and a second switch configured to open and close according to a first clock signal, the first switch and the second switch configured to pass the input signal when the first clock signal is in a first state, the first chopper circuit and the second chopper circuit further comprising a third switch and a fourth switch configured to open and close according to a second clock signal, the third switch and the fourth switch configured to pass an inverted input signal when the second clock signal is in a second state.
2 Assignments
0 Petitions
Accused Products
Abstract
An active circuit includes (a) a first chopper circuit that receives an input signal and a chopping signal of a frequency higher than a base band of the input signal, and that provides a modulated input signal; (b) an amplifier that receives the modulated input signal and that provides an amplified signal resulting from amplifying the modulated input signal; and (c) a second chopper circuit that receives the amplified signal and the chopping signal to provide an output signal. The chopping signal has a frequency that may be dynamically adjusted to accommodate changes in impedance and signal spectrum as a result of the operations of the chopper circuits. The active circuit further includes a low pass filter that receives the output signal and that attenuates components of the output signal above the base band of the input signal. In this manner 1/f noise introduced by the amplifier is eliminated or reduced.
42 Citations
17 Claims
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1. An active circuit, comprising:
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a first chopper circuit that receives an input signal and a chopping signal of a frequency higher than a base band of the input signal, and that provides a modulated input signal; an amplifier that receives the modulated input signal and that provides an amplified signal resulting form amplifying the modulated input signal; and a second chopper circuit that receives the amplified signal and the chopping signal to provide an output signal;
whereinthe first chopper circuit and the second chopper circuit further comprise a first switch and a second switch configured to open and close according to a first clock signal, the first switch and the second switch configured to pass the input signal when the first clock signal is in a first state, the first chopper circuit and the second chopper circuit further comprising a third switch and a fourth switch configured to open and close according to a second clock signal, the third switch and the fourth switch configured to pass an inverted input signal when the second clock signal is in a second state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for processing an input signal, comprising the steps of:
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chopping the input signal to produce a modulated input signal based upon a chopping signal by providing a first switch and a second switch configured to open and close according to a first clock signal, the first switch and the second switch configured to pass the input signal when the first clock signal is in a first state and providing a third switch and a fourth switch configured to open and close according to a second clock signal, the third switch and the fourth switch configured to pass an inverted input signal when the second clock signal is in a second state, the chopping signal having a frequency higher than a base band of the input signal, the modulated input signal having a frequency substantially similar to the chopping signal; amplifying the modulated input signal to produce an amplified signal; chopping the amplified signal to produce an output signal based upon the chopping signal; and dynamically selecting the frequency of the chopping signal such that harmonics of the chopping signal are outside a spectrum of the input signal. - View Dependent Claims (13, 14)
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15. An active circuit, comprising:
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means for chopping an input signal to produce a modulated input signal based upon a chopping signal, the chopping signal having a frequency higher than a base band of the input signal, the modulated input signal having a frequency substantially similar to the chopping signal; means for amplifying the modulated input signal to produce an amplified signal; means for chopping the amplified signal to produce an output signal based upon the chopping signal; and means for dynamically selecting the frequency of the chopping signal such that harmonics of the chopping signal are outside a spectrum of the input signal;
whereinthe chopping means further comprises a first switching means and a second switching means configured to open and close according to a first clock signal, the first switching means and the second switching means configured to pass the input signal when the first clock signal is in a first state, the chopping means further comprising a third switching means and a fourth switching means configured to open and close according to a second clock signal, the third switch and the fourth switch configured to pass an inverted input signal when the second clock signal is in a second state. - View Dependent Claims (16, 17)
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Specification