SiGe high-frequency pulse-width modulation for low-noise applications

This paper details the first-known experimental observation of pulse-width modulation at 100 MHz using silicon-germanium HBT technology. By performing pulse-width modulation (PWM) at a higher frequency, undesired harmonic-components—which are interpreted as noise—are likewise raised to higher frequencies. In doing so, the noise generated by the PWM controller can be raised to frequencies at which it is no longer relevant. Noise-free operation is guaranteed below the operating frequency of the PWM controller, so long as the semiconductor technology supports high-frequency waveform generation. Such capability is readily provided by modern silicon-germanium HBT technology. The paper also provides an integrated-circuit design with additional flexibility for the end user, with simulated performance results.