What are current-mode circuits and what advantages do they offer over voltage-mode?

Current-mode circuits process signals as currents rather than voltages. Advantages: Higher bandwidth (no need to charge node capacitances to specific voltages), Better linearity in some topologies, Lower supply voltage operation (signals not limited by voltage swing), and Natural implementation of mathematical operations (Kirchhoff current law). Examples: Current conveyors, log-domain filters (compress dynamic range using exponential I-V of transistors), translinear circuits. Challenges include: Higher noise (current noise sources), More sensitive to leakage, and Less intuitive design. Current-mode is particularly useful in high-frequency, low-power, and log-domain filtering applications.