Designing Ideas

In general, audio equalizers need second-order bandpass filters. If implements using state variable techniques you would need three op amps per channel. The basis for an alternative, Audio equalizer features transimpedance Q-enhancement topology, uses SAB (single-amplifier-biquadratic) filters requiring only two op amps per channel.

AMI (alternate-mark inversion) is a three-level—positive, zero, negative—copper-cable transmission code with the useful property of having no dc component for ease of ac coupling using capacitors or line-coupling transformers and a spectral peak at one-half the symbol rate. The Design Idea, AMI-to-NRZI-direct-conversion circuit tolerates unequalized pulse tails, details a simple circuit that can work with AMI pulses that have long pulse trails arising from the copper line.

Calculating the load impedance and power consumption at high frequencies in RF circuits is a tedious task. Virtual RF generator measures load impedance and power describes a National Instruments VI (virtual instrument) that provides an easy way to quickly and effectively measure these parameters.