High-Speed Full-Wave Rectification
Systems requiring power conversion and level detection employ full-wave rectification, traditionally provided by a diode bridge, but diode bridges consume a significant amount of board space and reduce signal amplitude. An alternative solution involves using separate amplification for the positive and negative half-cycles and a comparator to switch between them.
This solution typically requires numerous ICs and can suffer from delay mismatch between the two amplification paths. Because of this mismatch, this solution is acceptable only for low frequencies-where the delay mismatch is an insignificant percentage of the signal wavelength. Thus, designers who require a higher-frequency, broadband solution typically use the diode bridge configuration.
A third alternative uses an integrated multiplexer and amplifier along with a high-speed comparator (Figure 1). Since the amplifiers, switches, and final amplification are integrated in one device, delay mismatch issues are eliminated. This circuit’s frequency limit depends on the propagation delay of each stage, which are typically small, so this method can be used in high frequency applications.