Automatic gain control loop apparatus
First Claim
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1. A loop apparatus, comprising:
- a plurality of gain stages connected in series to amplify a radio frequency (RF) signal having a voltage, wherein each gain stage includes an input port that receives the RF signal and an output port that transmits the resulting amplified signal, and each gain stage increases the voltage of the RF signal; and
a plurality of feedback loops where each feedback loop is coupled to the output port and the input port of a corresponding one of the gain stages and such that each gain stage is connected to a corresponding feedback loop to cancel a direct current offset voltage of its corresponding gain stage, each feedback loop including a high-pass filter that filters the direct current offset voltage accumulated by its corresponding gain stage.
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Abstract
A DC offset cancelling circuit with multiple feedback loops suppresses DC offset voltages within an automatic gain control loop apparatus. The apparatus includes a plurality of gain stages connected in series that receive and amplify an input RF signal. Each gain stage includes a corresponding feedback loop to filter the DC offset voltage accumulated in the respective gain stage.
73 Citations
30 Claims
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1. A loop apparatus, comprising:
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a plurality of gain stages connected in series to amplify a radio frequency (RF) signal having a voltage, wherein each gain stage includes an input port that receives the RF signal and an output port that transmits the resulting amplified signal, and each gain stage increases the voltage of the RF signal; and a plurality of feedback loops where each feedback loop is coupled to the output port and the input port of a corresponding one of the gain stages and such that each gain stage is connected to a corresponding feedback loop to cancel a direct current offset voltage of its corresponding gain stage, each feedback loop including a high-pass filter that filters the direct current offset voltage accumulated by its corresponding gain stage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for controlling a gain of a radio frequency (RF) signal, comprising:
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amplifying the voltage of an RF signal by propagating the RF signal through a plurality of gain stages connected in series, wherein each gain stage increases the voltage of the RF signal, and includes an input port receiving the RF signal and an output port transmitting the resulting amplified signal; and canceling an undesired offset of each gain stage using a plurality of feedback loops, wherein each feedback loop is connected to the output port and the input port of a corresponding one of the gain stages, such that each gain stage is connected to a corresponding feedback loop that cancels the undesired offset of its corresponding gain stage, each feedback loop including a direct current offset canceling unit having a high-pass filter to cancel the undesired offset by its corresponding gain stage. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A direct conversion receiver, comprising:
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an amplification unit that receives and amplifies a radio frequency (RF) signal, wherein the amplification unit includes; a plurality of gain stages connected in series to amplify the RF signal having a voltage, wherein each gain stage includes an input port that receives the RF signal and an output port that transmits the resulting amplified signal, and each gain stage increases the voltage of the RF signal, and a plurality of feedback loops where each feedback loop is coupled to the output port and the input port of a corresponding one of the gain stages and such that each gain stage is connected to a corresponding feedback loop to cancel an undesired offset of its corresponding gain stage, each feedback loop including a direct current offset canceling unit having a high-pass filter to filter a direct current offset voltage; and a mixer that demodulates the amplified signal by mixing the amplified RF signal with a local oscillation signal to form a demodulated baseband signal. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification