Reference voltage generator for single-ended communication systems

摘要

A reference voltage (Vref) generator for a single-ended receiver in a communication system is disclosed. The Vref generator in one example comprises a cascoded current source for providing a current, I, to a resistor, Rb, to produce the Vref voltage (I*Rb). Because the current source isolates Vreffrom a first of two power supplies, Vref will vary only with the second power supply coupled to Rb. As such, the Vref generator can be used in systems employing signaling referenced to that second supply but having decoupled first supplies. For example, in a communication system in which the second supply (e.g., Vssq) is common to both devices, but the first supply (Vddq) is not, the disclosed Vref generator produces a value for Vref that tracks Vssq but not the first supply.

主权项

1. A method, comprising:
applying a first voltage and a second voltage to a reference voltage generator, the reference voltage generator comprising a series connection of a first transistor, a second transistor, and a resistor; and producing a reference voltage from the reference voltage generator at a node between the second transistor and the resistor, the reference voltage being dependent on the second voltage but not the first voltage.