Abstract: Disclosed herein is circuitry for protecting a power supply system from overcurrent conditions by monitoring an input voltage and an output voltage of the power supply system, detecting an overcurrent condition based on the monitored input and output voltages, and determining whether the overcurrent condition is caused by an input transient or an output short circuit. When the detected overcurrent condition is caused by an input transient, a gate of a power transistor is controlled to maintain current flow to a load. When the detected overcurrent condition is caused by an output short circuit, the power transistor is turned off to protect the power supply system.

Abstract: A digital radio frequency (RF) modulator provides modulation for base-band TV signals. The RF modulator provides direct conversion of digital base-band audio and video signals to a desired RF channel frequency, without any analog up conversion. The RF modulator includes an audio module, a video module, and a RF converter. The audio module includes a pre-emphasis filter, a multi-stage audio interpolator and a complex frequency modulator to generate frequency modulated (FM) audio signals. The video module includes a complex VSB filter, a group-delay compensation filter and some processing logic to generate a filtered output video signal. The RF converter includes a complex adder, a complex multiplier and a RF interpolator to construct the base band TV signals and to shift the base band TV signals in a frequency domain to the desired RF channel frequency. The exponential video carrier is generated at baseband and has a frequency whose value is in the range of +/?13.5 MHz.