Abstract: A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is processed by a digital filter. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. An adaptive electronic transmission signal cancellation circuit separates transmit data from receive data in a bidirectional communication system operating in full duplex mode.

Abstract: A power efficient and reduced electromagentic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Digital transmit data is converted to a current-mode differential signal analog waveform by a digital-to-analog converter (DAC). DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. Selection logic circuitry asserts command signals to individual line driver cells which operate the cells in either class-A or class-B, in operative response to a DAC control word. The same DAC control word adaptively configures the line driver cells to operate in accordance with at least two ethernet-type transmission standards. Numbers of line driver cells are adaptively disabled in operative response to a DAC control word, to conform the transmitter to differing transmission standards with differing voltage swing requirements.

Abstract: A digital FM stereo decoder uses the phase characteristics of linear phase FIR filters, together with a trignometric operation, to generate a 38 kHz subcarrier signal from a 19 kHz pilot. The subcarrier signal is mixed with the input composite signal from which the pilot has been removed to shift its L-R component to baseband; the linear phase FIR filters also maintain phase coherence between the subcarrier and the composite signals. A low distortion output is obtained without the use of a phase locked loop for the regeneration of the subcarrier signal.