Variable gain received signal strength indicator
AssigneeBroadcom Corporation
InventorsShahla Khorram, Shan Jiang
Life of this patent
Estimating the term…
Abstract
An RSSI circuit provides a relatively inexpensive technique for accurately measuring received signal strength over a wide dynamic range. A received signal is processed by a rectifier circuit that generates a series of DC offsets of increasing magnitude. The DC offsets are imposed on a first polarity of the received signal to create a series of outputs that are the first polarity of the received signal with increasing DC offsets. Each of the outputs is coupled to one input of a weighted comparator with the other input of the comparator coupled to a second and opposite polarity of the received signal with no offset. The comparators determine when overlap occurs to indicate particular signal levels.
Claims22
A method of measuring the strength of a received signal that is an AC signal having a dynamic range, said method comprising:
- converting the received signal to a first polarity of the received signal and to a second polarity of the received signal;
- generating a plurality of DC offsets of increasing value;
- imposing each of the plurality of DC offsets on the first polarity of the received signal to produce a plurality of DC offset first polarity received signals;
- comparing each of the plurality of DC offset first polarity received signals to the second polarity of the received signal;
- determining when one or more of the plurality of DC offset first polarity received signals is overcome by the second plurality of the received signal;
- and
- indicating the strength of the received signal based upon which of the plurality of DC offset first polarity received signals is overcome by the second plurality of the received signal.
An apparatus for measuring the strength of a received signal that is an AC signal having a dynamic range, said apparatus comprising:
- means for converting the received signal to a first polarity of the received signal and to a second polarity of the received signal;
- means for generating a plurality of DC offsets of increasing value;
- means for imposing each of the plurality of DC offsets on the first polarity of the received signal to produce a plurality of DC offset first polarity received signals;
- means for comparing each of the plurality of DC offset first polarity received signals to the second polarity of the received signal;
- means for determining when one or more of the plurality of DC offset first polarity received signals is overcome by the second plurality of the received signal;
- and
- means for indicating the strength of the received signal based upon which of the plurality of DC offset first polarity received signals is overcome by the second plurality of the received signal.
An apparatus for measuring the strength of a received signal that is an AC signal having a dynamic range, said apparatus comprising:
- a circuit that converts the received signal to a first polarity of the received signal and to a second polarity of the received signal;
- a rectifier circuit, said rectifier circuit further comprising:
- an offset circuit having an input for receiving the first polarity of the received signal and for producing a plurality of DC offset first polarity received signals using a plurality of DC offsets of increasing value;
- and
- a plurality of comparator circuits each having a first input for receiving a respective one of the plurality of DC offset first polarity received signals, a second input for receiving the second polarity of the received signal, and an output that is inactive when the amplitude of the signal on the second input is greater than the amplitude of the signal on the first input and active when the amplitude of the signal on the first input is greater than the amplitude of the signal on the second input;
- and
- wherein the strength of the received signal is thereby indicated by the active outputs of the comparators.
Dependencies are inferred from the claim text.