Automatic gain control in a zero intermediate frequency radio device
First Claim
1. A zero intermediate frequency radio device comprising:
- an antenna for receiving a radio frequency signal, said radio frequency signal exhibiting a high dynamic range;
a frequency down converter for down converting said radio frequency signal to a zero intermediate frequency signal, said frequency down converter comprising a mixer, an AC-coupler, and a received signal strength indicator with a signal resolving range that is below said high dynamic range, said AC-coupler being coupled to an output of said mixer;
a signal processor for processing said zero intermediate frequency signal;
at least one amplifier coupled between said antenna and said signal processor; and
an automatic gain controller for at least gain controlling said at least one amplifier, said automatic gain controller being configured to set a gain of said at least one amplifier by setting said gain to a predetermined gain, by waiting a predetermined time for allowing DC-offset signals in said radio device to decay, by checking whether a reading of said received signal strength indicator is within said signal resolving range, and by setting said gain in accordance with said reading if said reading is within said signal resolving range.
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Accused Products
Abstract
A zero intermediate frequency radio device has an antenna for receiving a radio frequency signal, and a frequency down converter for down converting the received radio frequency signal to a zero intermediate frequency signal. The radio device further has controllable amplifier stages, controllable AC-coupling stages, controllable filter stages, and a received signal strength indicator. A signal resolving range of the received signal strength indicator is below a high dynamic range of the received radio frequency signal. The radio device further has an automatic gain controller. The automatic gain controller initially sets the gain of the Rx path of the radio device to a maximum of minimum gain, and then waits for DC-offsets in the Rx path to cancel. If, at maximum or minimum gain, a reading of the received signal strength indicator is within a particular range, the automatic gain controller sets the gain to the reading. Then, automatic gain control settles. If this is not the case, the gain of the Rx path is stepwise decreased or increased, while repeating the DC-offset cancellation step of waiting for the DC-offset to cancel, until the reading of the received signal strength indicator falls in the signal resolving range around the then set gain of the Rx path.
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Citations
14 Claims
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1. A zero intermediate frequency radio device comprising:
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an antenna for receiving a radio frequency signal, said radio frequency signal exhibiting a high dynamic range;
a frequency down converter for down converting said radio frequency signal to a zero intermediate frequency signal, said frequency down converter comprising a mixer, an AC-coupler, and a received signal strength indicator with a signal resolving range that is below said high dynamic range, said AC-coupler being coupled to an output of said mixer;
a signal processor for processing said zero intermediate frequency signal;
at least one amplifier coupled between said antenna and said signal processor; and
an automatic gain controller for at least gain controlling said at least one amplifier, said automatic gain controller being configured to set a gain of said at least one amplifier by setting said gain to a predetermined gain, by waiting a predetermined time for allowing DC-offset signals in said radio device to decay, by checking whether a reading of said received signal strength indicator is within said signal resolving range, and by setting said gain in accordance with said reading if said reading is within said signal resolving range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A gain control method for gain controlling of a zero intermediate frequency radio device, said zero intermediate radio device comprising an antenna for receiving a radio frequency signal, said radio frequency signal exhibiting a high dynamic range, a frequency down converter for down converting said radio frequency signal to a zero intermediate frequency signal, said frequency down converter comprising a mixer, at least one amplifier, and an AC-coupler, said AC-coupler being coupled to an output of said mixer, and said zero intermediate frequency radio device further comprising a received signal strength indicator with a signal resolving range that is below said high dynamic range, said method comprising at least setting a gain of said at least one amplifier by:
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setting said gain to a predetermined gain;
waiting a predetermined time for allowing DC-offset signals in said radio device to decay;
checking whether a reading of said received signal strength indicator is within said signal resolving range; and
setting said gain in accordance with said reading if said reading is within said signal resolving range.
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Specification