A compensation technique for compact low-voltage low-power active-RC filters

This paper presents the compensation method for the active-RC integrators employing unbuffered low-gain opamp suitable for low-voltage low-power designs. The compensated integrators are then connected together in the cross-cascade fashion to synthesize the compact ladder-based fifth-order Chebyshev filters with 100-kHz and up to 10-MHz bandwidth, operating under 0.5-V single supply. Simulation results of the 100-kHz filter show a nearly identical with the prototype one. Its output signal-to-noise ratio (SNR) and spurious-free dynamic range (SFDR) are about 53.6 dB and 48.7 dBc, respectively, and consuming only 60.7 μW. The 10-MHz filter with tunable capability via weak inversion MOS varactors gives good potential at high frequency range. This technique shows a promise for ultra low-voltage low-power designs such as in bio-applications.