Automatic gain control circuit using a capacitor for minimizing digital coupling
AssigneeSGS-Thompson Microelectronics Pte. Ltd.
InventorSolomon Ng
Life of this patent
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Abstract
An automatic gain control circuit comprising a variable gain amplifier having first and second differential gain control terminals, the first gain control terminal being connected to a constant reference voltage, a peak detector connected to the output of the variable gain amplifier and an integrator connected between the output of the peak detector and the second differential gain control terminal. The circuit further includes an integrating capacitor coupled to a ground terminal and a second capacitor connected between the first and second differential gain control terminals.
Claims32
An automatic gain control circuit comprising:
- a variable gain amplifier having first and second differential gain control terminals, said first gain control terminal being connected to a constant reference voltage;
- a peak detector connected to an output of the variable gain amplifier;
- and
- an integrator connected between an output of the peak detector and the second differential gain control terminal, and including a first capacitor coupled to a ground terminal;
- the circuit characterized in that it comprises a second capacitor connected between the first and second differential gain control terminals.
An automatic gain control circuit comprising:
- a variable gain amplifier having first and second differential gain control terminals, said first differential gain control terminal being coupled to a constant reference voltage;
- a peak detector coupled to an output of the variable gain amplifier;
- an integrator coupled between an output of said peak detector and a ground terminal, and having an output coupled to said second differential gain control terminal;
- and
- means for minimizing noise from said ground terminal coupled between said first and second differential gain control terminals.
A method of minimizing noise in an automatic gain control circuit, the method comprising:
- amplifying an input signal in accordance with first and second differential gain control signals and outputting an amplified signal;
- detecting peaks of said amplified signal and outputting a peak signal;
- integrating said peak signal to provide said first differential gain control signal;
- and
- minimizing noise in said first differential gain control signal by capacitively coupling said first differential gain control signal to said second differential gain control signal.
An automatic gain control circuit comprising:
- a variable gain amplifier having an input, an output and first and second differential gain control terminals;
- an integrator coupled between the output of said variable gain amplifier and said first differential gain control terminal;
- and
- means for coupling high frequency noise on said first differential gain control terminal to said second differential gain control terminal;
- wherein said coupling means comprises a first capacitor having a first terminal coupled to said first differential gain control terminal and a second terminal coupled to said second differential gain control terminal.
An automatic gain control circuit comprising:
- a variable gain amplifier having first and second differential gain controls;
- a peak detector connected to an output of the variable gain amplifier;
- an integrator connected between an output of the peak detector and the second differential gain control, and including a noise filter;
- and
- a noise coupler that couples noise from the second differential gain control to the first differential gain control;
- wherein the noise coupler comprises a first capacitor.
An automatic gain control circuit comprising:
- a variable gain amplifier having first and second differential gain controls;
- a peak detector connected to an output of the variable gain amplifier;
- an integrator connected between an output of the peak detector and the second differential gain control, and including a noise filter;
- and
- means for coupling noise from the second differential gain control to the first differential gain control;
- wherein said means for coupling noise comprises a first capacitor.
A method for amplifying a signal and automatically controlling a gain of the signal comprising the steps of:
- variably amplifying the signal with a gain controlled by first and second differential gain controls;
- detecting peaks in the variably amplified signal;
- integrating the detected peaks;
- filtering the integrated detected peaks;
- feeding back the filtered integrated detected peaks to the second differential gain control terminal;
- and
- introducing noise from the second differential gain control to the first differential gain control;
- wherein the step of introducing noise from the second differential gain control to the first differential gain control comprises capacitatively coupling the second differential gain control and the first differential gain control.
Dependencies are inferred from the claim text.