A DESIGN OF SWITCHED-CURRENT AUTOTUNING FILTER AND ITS ANALYSIS

In this paper, a new switched-current autotuning filter is proposed. S witched-current (SI) isa current-mode analog sampled-data circuit tech nique. An SI circuit can be realized using only standard digital CMOS technologies, and is capable of realizing high frequency circuits. The proposed filter is composed of SI-OTA (operational transconductance a mplifier) integrators. The gain of an SI-OTA integrator can be electro nically controlled by the bias current. The proposed filter is a curre nt controlled filter (CCF) and a PLL technique was used as its tuning method. A 2nd-order SI auto-tuning low-pass filter with 100 kHz cutoff frequency was designed assuming a 2 mu m CMOS process. The characteri stics of this SI filter and its tuning characteristics were confirmed by SPICE simulations.