Low noise amplifier for multiple channels
First Claim
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1. A signal transmission system for use with a MEMS device having a beam movable in a plurality of axes, the system comprising:
- a first-axis variable capacitor disposed to respond to motion of the beam along a first axis, the first-axis variable capacitor driven by a periodic first-axis drive signal having a first-channel drive frequency;
a second-axis variable capacitor disposed to respond to motion of the beam along a second axis, the second-axis variable capacitor driven by a periodic second-axis drive signal having a second-channel drive frequency;
an amplifier having an amplifier input electrically coupled to the first-axis variable capacitor and the second-axis variable capacitor, to amplify first-axis motion and second-axis motion signals from the first-axis variable capacitor and the second-axis variable capacitor, respectively;
a plurality of demodulators operatively coupled with the amplifier for receiving amplified input signals from the amplifier, each demodulator comprising a switching arrangement, the plurality of demodulators comprising;
a first-channel demodulator driven by the periodic first-axis drive signal and operable to demodulate the amplified motion signals to produce a first-axis output signal including second-axis noise; and
a second-channel demodulator driven by the periodic second-axis drive signal and operable to demodulate the amplified motion signal to produce a second-axis output signal including first-axis noise;
a first-channel low-pass filter coupled to the first-channel demodulator, the first-channel low-pass filter having a cutoff frequency below the frequency of the second-axis noise generated by the second-channel demodulator; and
a second-channel low-pass filter coupled to the second-channel demodulator, the second-channel low-pass filter having a cutoff frequency below the frequency of the first-axis noise generated by the first-channel demodulator;
the filters mitigating the noise on their respective channels.
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Abstract
An amplifier system has an amplifier for amplifying a plurality of input signals from a plurality of different channels, and a plurality of demodulators each operatively coupled with the amplifier for receiving amplified input signals from the amplifier. Each demodulator is configured to demodulate a single amplified input channel signal from a single channel of the plurality of different channels. The system thus also has a plurality of filters, coupled with each of the demodulators, for mitigating the noise.
12 Citations
13 Claims
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1. A signal transmission system for use with a MEMS device having a beam movable in a plurality of axes, the system comprising:
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a first-axis variable capacitor disposed to respond to motion of the beam along a first axis, the first-axis variable capacitor driven by a periodic first-axis drive signal having a first-channel drive frequency; a second-axis variable capacitor disposed to respond to motion of the beam along a second axis, the second-axis variable capacitor driven by a periodic second-axis drive signal having a second-channel drive frequency; an amplifier having an amplifier input electrically coupled to the first-axis variable capacitor and the second-axis variable capacitor, to amplify first-axis motion and second-axis motion signals from the first-axis variable capacitor and the second-axis variable capacitor, respectively; a plurality of demodulators operatively coupled with the amplifier for receiving amplified input signals from the amplifier, each demodulator comprising a switching arrangement, the plurality of demodulators comprising; a first-channel demodulator driven by the periodic first-axis drive signal and operable to demodulate the amplified motion signals to produce a first-axis output signal including second-axis noise; and a second-channel demodulator driven by the periodic second-axis drive signal and operable to demodulate the amplified motion signal to produce a second-axis output signal including first-axis noise; a first-channel low-pass filter coupled to the first-channel demodulator, the first-channel low-pass filter having a cutoff frequency below the frequency of the second-axis noise generated by the second-channel demodulator; and a second-channel low-pass filter coupled to the second-channel demodulator, the second-channel low-pass filter having a cutoff frequency below the frequency of the first-axis noise generated by the first-channel demodulator; the filters mitigating the noise on their respective channels. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of processing a signal comprising:
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amplifying an input signal having a plurality of different channels to produce an amplified input signal having the plurality of different channels; demodulating the amplified input signal to produce at least one demodulated signal for each channel, demodulating causing each demodulated signal to have noise relating to at least one other channel, demodulating the amplified input signal comprising; providing the amplified input signal to a first-channel demodulator comprising a switching arrangement controlled by a first-channel drive signal; and simultaneously providing the amplified input signal to a second-channel demodulator comprising a switching arrangement controlled by a second-channel drive signal; and filtering each demodulated signal to mitigate the noise to produce a baseband signal for each of the plurality of channels; and forwarding each baseband signal from at least one output node. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification