Linear amplifier that perform level shift and method of level shifting
First Claim
1. A linear amplifier comprising:
- a signal input terminal that receives an input signal having a first common mode voltage;
a voltage amplifier having an inverting input terminal, a non-inverting input terminal to which a second common mode voltage is supplied, and an output terminal that outputs an output signal;
a first and a second input resistance connected in series from the signal input terminal to the inverting input terminal of the voltage amplifier;
a feedback resistance connected between the inverting input terminal and the output terminal of the voltage amplifier; and
a constant current source that supplies a constant current to a middle node between the first and second input resistances, the constant current generates a voltage drop, which is equal to a difference between the first and second common mode voltages, across the signal input terminal and the middle node.
2 Assignments
0 Petitions
Accused Products
Abstract
A linear amplifier that comprises a signal input terminal that receives an input signal having a first common mode voltage, a voltage amplifier having a non-inverting input terminal that receives a second common mode voltage, a first and a second input resistance connected in series from the signal input terminal to the inverting input terminal of the voltage amplifier, a feedback resistance connected between the inverting input terminal and the output terminal of the voltage amplifier, and a constant current source. The constant current source supplies a constant current to a middle node between the first and the second input resistances. The constant current generates a voltage drop, which is equal to a difference between the first and the second common mode voltages, across the first input resistance. Accordingly, the common mode voltage of the output signal is directly determined by the second common mode voltage.
8 Citations
19 Claims
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1. A linear amplifier comprising:
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a signal input terminal that receives an input signal having a first common mode voltage; a voltage amplifier having an inverting input terminal, a non-inverting input terminal to which a second common mode voltage is supplied, and an output terminal that outputs an output signal; a first and a second input resistance connected in series from the signal input terminal to the inverting input terminal of the voltage amplifier; a feedback resistance connected between the inverting input terminal and the output terminal of the voltage amplifier; and a constant current source that supplies a constant current to a middle node between the first and second input resistances, the constant current generates a voltage drop, which is equal to a difference between the first and second common mode voltages, across the signal input terminal and the middle node. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A linear amplifier comprising:
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a positive and a negative signal input terminal that receive a differential input signal having a first common mode voltage; a voltage amplifier having a non-inverting and an inverting input terminal, and a non-inverting and an inverting output terminal that output a differential output signal; a first and a second positive input resistance connected in series from the positive signal input terminal to the non-inverting input terminal of the voltage amplifier and a first and a second negative input resistance connected in series from the negative signal input terminal to the inverting input terminal of the voltage amplifier; a first feedback resistance connected between the inverting input terminal and the non-inverting output terminal of the voltage amplifier and a second feedback resistance connected between the non-inverting input terminal and the inverting output terminal of the voltage amplifier; and a constant current source that supplies a first constant current to a first middle node between the first and second positive input resistances and a second constant current to a second middle node between the first and second negative input resistances so that a voltage drop, which is equal to a difference between the first common mode voltage and a second common mode voltage, is generated across the positive signal input terminal and the first middle node and across the negative input terminal and the second middle node. - View Dependent Claims (8, 9, 10)
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11. A method of level shifting, comprising:
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receiving an input signal having an input common mode voltage equal to a first common mode voltage at a signal input terminal; inputting the input signal to an inverting input terminal of a voltage amplifier through a first and a second input resistance connected in series from the signal input terminal to the inverting input terminal; supplying a second common mode voltage to a non-inverting input terminal of the voltage amplifier;
outputting an output signal from an output terminal of the voltage amplifier;feeding back the output signal to the inverting input terminal of the voltage amplifier through a feedback resistance; and supplying a constant current to a middle node between the first and second input resistances to generate a voltage drop, which is equal to a difference between the first and second common mode voltages, across the signal input terminal and the middle node so that the input signal is input to the inverting input terminal of the voltage amplifier through the second input resistance after the input common mode voltage is shifted to the second common mode voltage. - View Dependent Claims (12, 13, 14, 15)
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16. A method of level shifting, comprising:
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receiving a differential input signal including a positive and a negative input signal, which has an input common mode voltage equal to a first common mode voltage, at a positive and a negative signal input terminal, respectively; inputting the positive input signal to a non-inverting input terminal of a voltage amplifier through a first and a second positive input resistance connected in series from the positive signal input terminal to the non-inverting input terminal and the negative input signal to an inverting input terminal of the voltage amplifier through a first and a second negative input resistance connected in series from the negative signal input terminal to the inverting input terminal; outputting a differential output signal including a positive and a negative output signal from a non-inverting and an inverting output terminal, respectively, of the voltage amplifier, feeding back the positive output signal to the inverting input terminal of the voltage amplifier through a first feedback resistance and the negative output signal to the non-inverting input terminal of the voltage amplifier through a second feedback resistance; supplying a first constant current to a first middle node between the first and second positive resistances and a second constant current to a second middle node between the first and second negative resistances; and generating a voltage drop, which is equal to a difference between the first common mode voltage and a second common mode voltage, across the positive signal input terminal and the first middle node and across the negative signal input terminal and the second middle node so that the positive and negative input signals are input to the non-inverting and inverting input terminals of the voltage amplifier through the second positive and second negative input resistances, respectively, after the input common mode voltage is shifted to the second common mode voltage. - View Dependent Claims (17, 18, 19)
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Specification