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US 8,570,099 B2Granted
Single-ended-to-differential filter using common mode feedback
AssigneeSynopsys, Inc.
InventorsKa Hou Ao Ieong, Seng Pan U
Life of this patent
Estimating the term…
Abstract
A filter including common mode feedback can provide single-ended to differential-ended conversion with minimum loss of performance.
Claims15
A filter for providing single-ended to differential-ended signal conversion, the filter comprising:
- a first buffer receiving an analog signal;
- a first resistor;
- a second resistor;
- a second buffer, wherein the first buffer, the first resistor, the second resistor, and the second buffer are connected in series;
- a first capacitor connected between an input of the second buffer and a low voltage source;
- a third buffer receiving a DC signal;
- a third resistor;
- a fourth resistor;
- a fourth buffer, wherein the third buffer, the third resistor, the fourth resistor, and the fourth buffer are connected in series;
- a second capacitor connected between an input of the fourth buffer and the low voltage source;
- and
- a common mode feedback circuit connected between the first and the second resistors as well as between the third and the fourth resistors,
- wherein the common mode feedback circuit compares a common mode voltage and a reference voltage and, based on that comparison, modifies voltages on the second and the fourth resistors by application of current,
- wherein the second buffer outputs a first differential voltage and the fourth buffer outputs a second differential voltage.
11 more elements
A filter for providing single-ended to differential-ended signal conversion, the filter comprising:
- a first buffer receiving an analog signal;
- a first resistor;
- a first RC network, wherein the first buffer, the first resistor, and the first RC network are connected in series, the first RC network including a second resistor and a first capacitor connected in parallel;
- a second buffer receiving a DC signal;
- a third resistor;
- a second RC network, wherein the second buffer, the third resistor, and the second RC network are connected in series, the second RC network including a fourth resistor and a second capacitor connected in parallel;
- a common mode feedback circuit connected between the first and the second resistors as well as between the third and the fourth resistors;
- and
- a differential amplifier connected to the first and the second RC networks,
- wherein the common mode feedback circuit compares a common mode voltage and a reference voltage and, based on that comparison, modifies voltages on the second and the fourth resistors by application of current,
- wherein the first RC network outputs a first differential voltage and the second RC network outputs a second differential voltage.
8 more elements
Dependencies are inferred from the claim text.