Current-mode delay equalizer design using multiple output OTAs

Two new current-mode allpass sections based on dual-output OTAs (DO-OTAs) a nd triple-output OTAs (TO-OTAs) and grounded capacitors are described. Tech niques to minimize the equalizer active device count and efficiently simula te grounded resistors are proposed. A fifth-order group delay equalizer bas ed on the presented allpass sections is designed and simulated using multip le-output CMOS OTAs. Numerical optimization is used to determine the equali zer order and parameters. SPICE simulation results are given, demonstrating that the equalizer can effectively compensate the delay characteristic of a fourth-order 4 MHz lowpass Chebyshev filter to less than or equal to 8 ns ripple over 90% of the filter passband.