Linearizing apparatus and method
First Claim
1. An apparatus to provide a substantially linear relationship between an input signal and a selected parameter, the apparatus comprising:
- a square root converter capable of being coupled to receive the input signal, the square root converter adapted to provide a square root signal, the square root signal substantially proportional to a square root of the input signal; and
circuitry comprising a logarithmic generator couplable to receive the input signal and coupled to the square root converter, the logarithmic generator adapted to provide an applied signal for substantially linear control of the selected parameter in response to the input signal, the applied signal substantially proportional to a sum or superposition of the square root signal and a logarithm of the input signal.
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Accused Products
Abstract
An apparatus and method are disclosed which provide a substantially linear relationship between an input signal, such as an input voltage or current, and a predetermined parameter, such as a frequency response or capacitance of a parallel plate capacitor or varactor. The apparatus comprises a square root converter and a logarithmic generator. The square root converter is adapted to provide a square root signal which is substantially proportional to a square root of the input signal. In the various embodiments, the logarithmic generator is adapted to provide an applied signal which is substantially proportional to a sum of a logarithm of the input signal plus the square root of the input signal. The applied signal is a pre-distorted signal which generally has a non-linear relation to the predetermined parameter and which, when applied, allows the predetermined parameter to vary substantially linearly with the input signal.
30 Citations
31 Claims
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1. An apparatus to provide a substantially linear relationship between an input signal and a selected parameter, the apparatus comprising:
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a square root converter capable of being coupled to receive the input signal, the square root converter adapted to provide a square root signal, the square root signal substantially proportional to a square root of the input signal; and circuitry comprising a logarithmic generator couplable to receive the input signal and coupled to the square root converter, the logarithmic generator adapted to provide an applied signal for substantially linear control of the selected parameter in response to the input signal, the applied signal substantially proportional to a sum or superposition of the square root signal and a logarithm of the input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A circuit to provide a substantially linear relationship between an input voltage and a frequency response of a capacitor, the circuit comprising:
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a voltage-to-current converter, the voltage-to-current converter capable of being coupled to receive the input voltage, the voltage-to-current converter capable of providing an input current substantially linearly proportional to the input voltage; a current mirror coupled to the voltage-to-current converter; a square root converter coupled to the current mirror to receive the input current, the square root converter capable of providing a first output voltage substantially proportional to a square root of a magnitude of the input current; and circuitry comprising a logarithmic generator coupled to the square root converter to receive the first output voltage and coupled to the current mirror to receive the input current, the circuitry adapted to provide a second output voltage substantially proportional to a sum or superposition of the first output voltage and a logarithm of the magnitude of the input current, the second output voltage capable of being coupled to the capacitor for a substantially linear frequency response to the input signal. - View Dependent Claims (23, 24, 25)
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26. An apparatus to provide a substantially linear relationship between an input voltage and a predetermined circuit parameter, the apparatus comprising:
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a voltage-to-current converter, the voltage-to-current converter capable of being coupled to receive the input voltage, the voltage-to-current converter capable of providing an input current substantially linearly proportional to the input voltage; a current mirror coupled to the voltage-to-current converter; a square root converter coupled to the current mirror to receive the input current, the square root converter capable of providing a first output voltage substantially proportional to a square root of a magnitude of the input current; a logarithmic generator coupled to the current mirror to receive the input current, the logarithmic generator capable of providing a second output voltage substantially proportional to a logarithm of the magnitude of the input current; and a combiner coupled to the square root converter to receive the first output voltage and coupled to the logarithmic generator to receive the second output voltage, the combiner adapted to provide an applied signal substantially equal to a sum or superposition of the first output voltage and the second output voltage, wherein the applied signal has a substantially nonlinear relationship to the predetermined parameter.
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27. A method of providing a substantially linear relationship between an input voltage and a predetermined circuit parameter, the method comprising:
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converting the input voltage to an input current, wherein the input current is substantially linearly proportional to the input voltage; generating a square root voltage from the input current, wherein the square root voltage is substantially proportional to a square root of a magnitude of the input current; generating a logarithmic voltage from the input current, wherein the logarithmic voltage is substantially proportional to a logarithm of the magnitude of the input current, and wherein the logarithmic voltage is substantially equal to a 3/2 power of the input current; and combining the square root voltage and the logarithmic voltage to form an applied signal substantially equal to a sum or superposition of the square root voltage and the logarithmic voltage, wherein the applied signal has a substantially nonlinear relationship to the predetermined parameter; and applying the applied signal to vary the predetermined circuit parameter substantially linearly with the input voltage.
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28. A method to create a substantially linear relationship between an input signal and a selected parameter, comprising:
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(a) receiving the input signal; (b) determining a square root of a magnitude of the input signal to form a square root signal; (c) determining a logarithm of the magnitude of the input signal to form a logarithmic signal; (d) combining the square root signal with the logarithmic signal to form an applied signal, the applied signal having a substantially nonlinear relationship to the input signal; and (e) providing the applied signal for adjustment of the selected parameter substantially linearly with the input signal. - View Dependent Claims (29)
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30. A method to create a substantially linear relationship between an input signal and a selected parameter, comprising:
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(a) receiving the input signal; (b) determining a square root of a magnitude of the input signal to form a square root signal; (c) determining a 3/2 power of the magnitude of the input signal to form a power signal; (d) combining the square root signal with the power signal to form an applied signal, the applied signal having a substantially nonlinear relationship to the input signal; and (e) providing the applied signal for adjustment of the selected parameter substantially linearly with the input signal.
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31. An apparatus to provide a substantially linear relationship between an input signal and a selected parameter, the apparatus comprising:
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a voltage-to-current converter couplable to receive the input signal as an input voltage and adapted to provide an input current having a substantially linear relationship to the input voltage; a square root converter coupled to the voltage-to-current converter to receive the input current, the square root converter adapted to provide a square root signal, the square root signal substantially proportional to a square root of the input current; and circuitry comprising a logarithmic generator coupled to the voltage-to-current converter to receive the input current and coupled to the square root converter, the circuitry adapted to provide an applied signal substantially proportional to a sum or a superposition of the square root signal and a logarithm of the input signal.
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Specification