US Patent 7280062 Pulse metering architecture

In one embodiment, a subscriber line interface circuit includes circuitry to generate metering pulses for insertion onto a subscriber line. The circuitry includes a cascaded digital-to-analog converter (DAC) structure including a first DAC to convert a digital sine wave into an analog representation, a second DAC to multiply the analog representation with a ramp value to obtain an unscaled output, and a third DAC to multiply the unscaled output with a gain value to generate a metering pulse.