US 8,559,558 B2 · Reference voltage generator for single-ended communication systems

Abstract

In various embodiments, 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 Vref from a first of two power supplies, Vref will vary only with the second power supply coupled to Rb. As such, the Vref generator is useful 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.

Claims21

Dependent claims

A communication system, comprising:

a receiver powered by a first power supply voltage and a second power supply voltage, the receiver to receive input data from a communication channel and to receive a reference voltage, the input data is to be referenced to the first power supply voltage, the input data having a reduced swing signal in which one logic state comprises the first power supply voltage and another logic state comprises a voltage between the first power supply voltage and the second power supply voltage, the receiver is to compare the input data to the reference voltage;
and
a generator to produce the reference voltage, the reference voltage being independent of the second power supply.

Dependencies are inferred from the claim text.

Reference voltage generator for single-ended communication systems

Life of this patent

Reference voltage generator for single-ended communication systems

Life of this patent

Abstract

Claims21