Stabilizing common mode of differential switching output stage
AssigneeAnalog Devices International Unlimited Company
InventorsNaoaki NISHIMURA, Atsushi MATAMURA, Abhishek BANDYOPADHYAY, Mariana Tosheva MARKOVA
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Abstract
Differential switching output stage for audio, power and digital data transmission can cause a common mode error due to asymmetric transition between positive and negative outputs. Systems and methods are provided for common mode error correction. In particular, summing nodes, novel error amps an edge switching can be used for common-mode feedback (CMFB) in differential signaling and other applications.
Claims20
A common-mode feedback circuit comprising:
- a differential amplifier having a positive output and negative output;
- an adder circuit configured to extract the common mode from the positive output and negative output;
- a feedback amplifier configured to correct the common mode;
- an output stage;
- and
- a switching network, the switching network configured to control the correction of the common mode only during transitions in the differential amplifier.
A method for providing common mode feedback in a differential amplifier, the method comprising:
- producing a first signal in the differential amplifier;
- producing a second signal in the differential amplifier;
- extracting the common mode from the first and second signal;
- comparing the common mode to a reference voltage;
- and
- feeding back the difference between the common mode and the reference voltage in the differential amplifier.
A circuit for providing common mode feedback in a differential amplifier, the circuit comprising:
- means for producing a first signal in the differential amplifier;
- means for producing a second signal in the differential amplifier;
- means for extracting the common mode from the first and second signal;
- means for comparing the common mode to a reference voltage;
- and, means for feeding back the difference between the common and the reference voltage in the differential amplifier.
Dependencies are inferred from the claim text.