Adjustable-Gain Difference Amplifier Circuit Measures Hundreds of Volts, Rejects Large Common-Mode Signals

A diff-amp in a feedback loop with an inverting op amp is useful for measuring differential signals up to 500 V. This circuit also rejects large common-mode voltages, and allows the differential gain to be set by a ratio of resistors, enabling the user to select the level of attenuation.

Designing High-Performance Phase-Locked Loops with High-Voltage VCOs

Phase-locked loops are used to provide the local-oscillator function in radio receivers and transmitters; for clock distribution and noise reduction, and as the clock source for high-sampling-rate analog-to-digital converters. This article considers the basics of PLLs, examines the current state-of-the-art in PLL design, discusses pros and cons of typical architectures, and introduces some alternatives to high-voltage VCOs.