Techniques for enabling a 10BT active output impedance line driver using a low power supply
AssigneeBroadcom Corporation
InventorsOvidiu Bajdechi, Christopher M. Ward
Life of this patent
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Abstract
A line driver for generating 10 BT signals is disclosed. Digital symbols to be transmitted via a 10 BT Ethernet line are converted by a digital-to-analog converter into a corresponding analog voltage signal, which is fed into an active output impedance line driver. The digital-to-analog converter also receives a reference voltage reflecting variations of the supply voltage and adjusts its output signal accordingly to provide a deliberately variable analog voltage signal to the line driver.
Claims22
An integrated circuit including an active output impedance line driver circuit comprising a differential amplifier, the negative input terminal coupled via an input resistor to an input terminal, the positive output terminal providing an output signal, wherein at least a feedback resistor forms a negative feedback path, and wherein the positive feedback path is shorted and coupled by an adjustable termination resistor to the residual in- and output terminal of the line driver and a common mode voltage source.
An integrated circuit including a system for producing a 10 BT Ethernet signal from digital symbols to be transmitted comprising:
- digital-to-analog converter (DAC) for converting the digital symbols to a corresponding analog voltage signal and
- an active output impedance line driver receiving the analog voltage signal as input and producing the corresponding 10 BT Ethernet signal and
- a calibration circuit for producing a digital word used to calibrate a termination resistor and
- a reference circuit producing a voltage reflecting an amplitude of the supply voltage of the active output impedance line driver, and
- wherein the DAC is coupled to the reference circuit and the reference signal controls the amplitude of the analog signal to follow variations of the supply voltage proportionally.
Dependencies are inferred from the claim text.