Feedback technique and filter and method
OwnerJamaal Mitchellinventor
Life of this patent
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Abstract
An example filter includes a differential amplifier and a resistor string coupled between output terminals of the differential amplifier. The resistor string may generate a common mode sense voltage and an intermediate voltage at an intermediate node. A feedback resistor is coupled between the intermediate node of the resistor string and an input terminal of the differential amplifier, and a feedback capacitor is coupled between a differential output terminal of the amplifier and the differential input terminal. Applying feedback in this manner may reduce area and power requirements of the filter to achieve selected frequency and gain performance.
Claims25
A filter, comprising:
- a differential amplifier including first and second differential input terminals and first and second differential output terminals;
- a resistor string including a plurality of resistive elements coupled between the first and second differential output terminals, wherein the resistor string is configured to provide a common mode sense voltage, and wherein the resistor string includes an intermediate node located between the first and second differential output terminals and configured such that a voltage having a value between the voltages at the first and second differential output terminals is generated at the intermediate node;
- a feedback resistor coupled between the intermediate node of the resistor string and the first differential input terminal;
- and
- a feedback capacitor coupled between the first differential output terminal and the first differential input terminal.
A system for baseband communications, comprising:
- a filter configured to filter and amplify a receive signal to thereby generate an analog output signal, the filter including:
- an amplifier having an input terminal and an output terminal;
- a feedback capacitor coupled between the input terminal and the output terminal;
- a voltage-generating resistor coupled to the output terminal and configured to generate a sense voltage at an intermediate node;
- and
- a feedback resistor coupled between the intermediate node and the input terminal;
- and
- an analog-to-digital converter configured to receive the analog output signal and generate a digital output signal.
A feedback method in a baseband communications filter having a resistor string coupled across the filter output, the method comprising:
- generating a common mode sense voltage with the resistor string;
- generating an intermediate voltage with the resistor string;
- and
- feeding back a current to a filter input based on a feedback resistor and the intermediate voltage.
A feedback method for an amplifier generating an output signal, the method comprising:
- attenuating the output signal;
- feeding back the attenuated output signal to an input terminal of the amplifier through a first impedance element;
- and
- feeding back the output signal to the input terminal of the amplifier through a second impedance element, wherein the output signal being fed back through the second impedance element is less attenuated than the output signal fed back through the first impedance element.
Dependencies are inferred from the claim text.