US 7,460,623 B1 · Digital two-stage automatic gain control

Abstract

A digital automatic gain control circuit is disclosed. The circuit includes a selector, a scaler, a detector, a gain adjustor and a controller. In one exemplary aspect, the selector receives an input signal having two components, namely, the in-phase (I) and quadrature (Q) components, in digital form. The selector then selects a subset of bits from each component based on a control signal provided by the controller. The two subsets are then forwarded to the scaler. The scaler then multiplies the two subsets respectively against a gain value to generate two multiplication results. A portion of each multiplication result is then provided as output by the scaler. The gain value and the subset selection are periodically adjusted in response to the scaler output. The adjustments with respect to the gain value and the subset selection are effectuated collectively by the detector, the gain adjustor and the controller.

Claims41

Dependent claims

A system for providing automatic gain control, comprising:

a selector configured to receive an input signal having a first component and a second component, the first component and the second component being in digital form, the selector further configured to select respective bit portions from the first and second components based on a control signal to generate a first selected output and a second selected output;
a scaler configured to receive the first and second selected outputs, to multiply the first and second selected outputs against a gain value, and to generate a first scaled output and a second scaled output respectively;
a gain adjustor configured to provide the gain value and to adjust the gain value based on a signal derived from the first and second scaled outputs, wherein,
the gain adjustor includes first and second cascaded up/down counters,
the gain value is provided at the output of the first counter, and
in a first state, the signal representing the first and second scaled outputs is communicated to the first counter, and in a second state, the signal representing the first and second scaled outputs is communicated to the second counter;
and
a controller configured to adjust the control signal based on the gain value.

5 more elements

An automatic gain control circuit, comprising:

a selector circuit configured to receive a plurality of input signals, each input signal having a first component and a second component, the first and second components being in digital form, the selector circuit further configured to select respective bit portions from the first and second components of each input signal based on a corresponding control signal to generate a pair of corresponding first and second selected outputs for each input signal;
a scaler circuit configured to receive the corresponding pairs of first and second selected outputs for the plurality of input signals and multiply each corresponding pair of first and second selected outputs against a corresponding gain value and generate a corresponding pair of first and second scaled outputs;
and
a plurality of gain processing circuits, each gain processing circuit associated with an input signal and configured to adjust the corresponding gain value and control signal for the associated input signal based on the corresponding pair of first and second scaled outputs wherein at least one of the gain processing further comprises
a gain adjustor configured to adjust the corresponding gain value based on the corresponding pair of first and second scaled outputs;
a controller configured to adjust the corresponding control signal based on the gain value;
and
a mechanism that applies corrections to the corresponding gain value so to maintain the corresponding gain value within a predetermined range that is narrower than the entire range of possible values while applying complementary adjustments to the control signal.

5 more elements

A circuit configured to provide automatic gain control, comprising:

a selector configured to scale down an input signal having a first component and a second component and generate a first selected output and a second selected output using a control signal and the first component and the second component respectively, wherein the first and second components are in digital form;
a scaler configured to generate a first scaled output and a second scaled output using the first and second selected outputs and a gain value;
a gain adjustor configured to adjust the gain value using the first and second scaled outputs;
and
a controller configured to adjust the control signal using the gain value, the controller also being configured to control the speed at which the gain adjustor adjusts the gain value;
wherein:
the gain adjustor is capable of operating in one of a plurality of modes including an acquisition mode and a tracking mode;
during the acquisition mode, the gain adjustor seeks an optimal level for the gain value, the optimal level being within a predetermined range having two delimiting limits, the predetermined range being narrower than the entire range of possible values;
during the tracking mode, the gain adjustor maintains the optimal level for the gain value;
and
during the tracking mode, upon the gain value reaching either one of the two delimiting limits, the gain adjustor and the controller simultaneously adjust the gain value and the control signal respectively, thereby maintaining a composite gain for the circuit relatively unchanged while keeping the gain value within the predetermined range.

8 more elements

An automatic gain control circuit, comprising:

a selector circuit configured to receive a plurality of input signals, each input signal having a first component and a second component, the first and second components being in digital form, the selector circuit further configured to select respective bit portions from the first and second components of each input signal based on a corresponding control signal to generate a pair of corresponding first and second selected outputs for each input signal;
a scaler circuit configured to receive the corresponding pairs of first and second selected outputs for the plurality of input signals and multiply each corresponding pair of first and second selected outputs against a corresponding gain value and generate a corresponding pair of first and second scaled outputs;
and
a plurality of gain processing circuits, each gain processing circuit associated with an input signal and configured to adjust the corresponding gain value and control signal for the associated input signal based on the corresponding pair of first and second scaled outputs wherein at least one of the gain processing further comprises:
a gain adjustor configured to adjust the corresponding gain value based on the corresponding pair of first and second scaled outputs;
and
a controller configured to adjust the corresponding control signal based on the gain value, and further configured to generate a second control signal;
wherein:
the gain adjustor operates in one of a plurality of modes including an acquisition mode and a tracking mode, the mode being determined by the second control signal;
during the acquisition mode, the gain adjustor seeks an optimal level for the corresponding gain value, the optimal level being within a predetermined range having two delimiting limits;
during the tracking mode, the gain adjustor maintains the optimal level for the corresponding gain value;
and
during the tracking mode, upon the corresponding gain value reaching either one of the two delimiting limits, the gain adjustor and the controller simultaneously adjust the corresponding gain value and the corresponding control signal respectively, thereby maintaining a corresponding composite gain for the system relatively unchanged while keeping the corresponding gain value within the predetermined range.

10 more elements

Dependencies are inferred from the claim text.

Digital two-stage automatic gain control

Life of this patent

Digital two-stage automatic gain control

Life of this patent

Abstract

Claims41