Power sensor for RF power amplifier
First Claim
1. A system for sensing RF amplifier output power comprising:
- a RF amplifier transistor configured to receive and amplify a RF signal;
a sampling transistor configured to receive and amplify a RF signal, wherein the sampling transistor is physically smaller than the RF amplifier transistor such that the sampling transistor is capable of producing a proportionally smaller amplified RF signal than that capable of being produced by the RF amplifier transistor for a RF input signal common to both the RF amplifier transistor and the sampling transistor; and
a current sensing circuit configured to receive a RF signal amplified by the sampling transistor and generate a current proportional to a RF signal amplified by the RF amplifier transistor.
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Abstract
A system for sensing RF amplifier output power includes an amplifier transistor and a sampling transistor that is physically smaller than the amplifier transistor. The sampling transistor is configured to sample the same RF input signal that is amplified by the amplifier transistor. A bias circuit associated with the transistors includes a selection of components based upon operating parameters as well as actual physical sizes of the transistors. The selection of component values in association with transistor sizes is used to enable generation of a current sensing signal that is proportional to the power level of the RF output signal generated by the amplifier transistor.
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Citations
15 Claims
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1. A system for sensing RF amplifier output power comprising:
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a RF amplifier transistor configured to receive and amplify a RF signal;
a sampling transistor configured to receive and amplify a RF signal, wherein the sampling transistor is physically smaller than the RF amplifier transistor such that the sampling transistor is capable of producing a proportionally smaller amplified RF signal than that capable of being produced by the RF amplifier transistor for a RF input signal common to both the RF amplifier transistor and the sampling transistor; and
a current sensing circuit configured to receive a RF signal amplified by the sampling transistor and generate a current proportional to a RF signal amplified by the RF amplifier transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for sensing RF amplifier output power comprising:
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means for amplifying a RF input signal and generating a RF output signal therefrom;
means for sampling a RF input signal that is associated with both the amplifying means and the sampling means and generating a sampled signal therefrom; and
means for sensing the sampled signal and generating a current sensing signal therefrom proportional to a power amplitude associated with the RF output signal. - View Dependent Claims (10, 11, 12)
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13. A method for sensing RF signal power amplitude, the method comprising the steps of:
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(a) providing a RF signal amplifier comprising a first transistor having a first predetermined size;
(b) providing a sampling amplifier comprising a second transistor having a second predetermined size that is smaller than the first predetermined size;
(c) amplifying a RF input signal to produce a first RF output signal; and
(d) sampling the RF input signal to produce a second RF output signal proportional to the first RF output signal, wherein the proportion is associated with a ratio determined by the first and second predetermined sizes.
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14. The method of step 13 further comprising the step of:
(e) converting the second RF output signal to a current sensing signal such that the current sensing signal is proportional to a power amplitude associated with the first RF output signal.
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15. A system for sensing RF amplifier output power comprising:
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a RF amplifier transistor configured to receive and amplify a RF signal;
a sampling transistor configured to receive and amplify a RF signal, wherein the sampling transistor is physically smaller than the RF amplifier transistor such that the sampling transistor is capable of producing a proportionally smaller amplified RF signal than that capable of being produced by the RF amplifier transistor for a RF input signal common to both the RF amplifier transistor and the sampling transistor;
a current sensing circuit configured to receive a RF signal amplified by the sampling transistor and generate a current proportional to a power amplitude associated with the RF signal amplified by the RF amplifier transistor; and
a bias circuit configured to establish quiescent operating characteristics associated with the RF amplifier transistor and the sampling transistor, the bias circuit comprising a first bias resistor associated with the RF amplifier transistor and further comprising a second bias resistor associated with the sampling transistor, wherein a ratio of resistor values between the first bias resistor and the second bias resistor is substantially equal to a ratio of physical sizes between the sampling transistor and the RF amplifier transistor.
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Specification