Acceleration sensing device having negative feedback loop
First Claim
Patent Images
1. An acceleration sensing device comprising:
- an acceleration sensor for generating an output signal corresponding to an acceleration applied to said acceleration sensor;
a DC amplifier, having a first input connected to said acceleration sensor, for amplifying the output signal of said acceleration sensor to generate an acceleration output, said DC amplifier having a DC amplification characteristic; and
a negative feedback circuit, connected between the output and a second input of said DC amplifier, said negative feedback circuit including a low-pass filter for negative feeding a low frequency component of an output signal of said DC amplifier back to said second input of said DC amplifier while blocking a high frequency component of said output signal from being fed back to said second input, said first and second inputs comprising, in operation, low frequency components of opposite polarity, thereby causing said DC ampifier to produce said output signal substantially without both offset voltage and thermal drift.
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Abstract
An output signal of an acceleration sensor is supplied to a DC amplifier to thereby generate an acceleration output. A low frequency component of the acceleration output of the DC amplifier is negatively fed back by a feedback circuit to the input of the DC amplifier.
23 Citations
29 Claims
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1. An acceleration sensing device comprising:
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an acceleration sensor for generating an output signal corresponding to an acceleration applied to said acceleration sensor; a DC amplifier, having a first input connected to said acceleration sensor, for amplifying the output signal of said acceleration sensor to generate an acceleration output, said DC amplifier having a DC amplification characteristic; and a negative feedback circuit, connected between the output and a second input of said DC amplifier, said negative feedback circuit including a low-pass filter for negative feeding a low frequency component of an output signal of said DC amplifier back to said second input of said DC amplifier while blocking a high frequency component of said output signal from being fed back to said second input, said first and second inputs comprising, in operation, low frequency components of opposite polarity, thereby causing said DC ampifier to produce said output signal substantially without both offset voltage and thermal drift. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An acceleration sensing device comprising:
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an acceleration sensor of a bridge circuit type including at least one resistor whose resistance value is changeable in response to an acceleration applied to said acceleration sensor, said sensor generating a first output signal corresponding to said acceleration from a first point thereof and a second output signal from a second point diagonal to said first point; a first DC amplifier, having a first input connected to said acceleration sensor, for amplifying the first output signal of said acceleration sensor, said DC amplifier having a DC amplification characteristic; a first negative feedback circuit, connected between the output and a second of said first DC amplifier, said first negative feedback circuit including a first low-pass filter for negatively feeding a low frequency component and a DC component of an output signal back to said first DC amplifier while blocking a high frequency component of said output signal of said first DC amplifier; a second DC amplifier, having a first input connected to said acceleration sensor, for amplifying the second output signal of said acceleration sensor, said DC amplifier having a DC amplification characteristic; a second negative feedback circuit, connected between the output and a second input of said second DC amplifier, said second negative feedback circuit including a second low-pass filter for negatively feeding a low frequency component and a DC component of an output signal back to said second DC amplifier while blocking a high frequency component of said output signal of said second DC amplifier; said first and second negative feedback circuits, in operation, feeding low frequency components back to said second inputs, said low frequency components having an opposite polarity as those low frequency components present on said first inputs, thereby causing said first and second DC amplifiers to produce output signals substantially without both offset voltage and thermal drift and an adder circuit, connected to said first and second DC amplifiers, for differentially adding the output of said first DC amplifier to that of said second DC amplifier to generate an acceleration output. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An acceleration sensing device comprising:
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an acceleration sensor for generating an output signal corresponding to an acceleration applied to said acceleration sensor; a DC amplifier, connected to said acceleration sensor, for amplifying the output signal of said acceleration sensor to generate an acceleration output, said DC amplifier having a DC amplification characteristic; a negative feedback circuit, connected between the output and input of said DC amplifier, for negatively feeding a low frequency component thereof to the input of said DC amplifier; and a switch means connected to said negative feedback circuit for enabling said negative feedback circuit when said switch means is turned ON and disabling said negative feedback circuit when said switch is turned OFF.
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29. An acceleration sensing device comprising:
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an acceleration sensor for generating an output signal corresponding to an acceleration applied to said acceleration sensor; a DC amplifier, connected to said acceleration sensor, for amplifying the output signal of said acceleration sensor to generate an acceleration output, said DC amplifier having a DC amplification characteristic; a negative feedback circuit, connected between the output and input of said DC amplifier, for negatively feeding a low frequency component thereof to the input of said DC amplifier; and a resistance variable means, connected to said negative feedback circuit, for enabling said negative feedback circuit when said resistance variable means has a small resistance value and disabling said negative feedback circuit when said resistance variable means has a large resistance value.
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Specification