Patent attributes
A low-noise transmitter architecture and method for high linearity, high output-swing systems such as Asymmetrical Digital Subscriber Line (ADSL) systems. The transmitter uses a switched-current DAC having a current source coupled to ground, followed by a current-to-voltage converter. The resistance of the current source is typically large enough so that noise from an op-amp included in the current-to-voltage converter is not significantly amplified at the output. The current source may be passive and may include at least one resistor connected to ground. With a passive current source, portions of a signal output by the DAC enter either the current source or the current-to-voltage converter, but not both, eliminating noise in the system produced by the current source.
