A Design of Switched-Current Auto-Tuning Filter and Its Analysis

Yoshito OHUCHI  Takahiro INOUE  Hiroaki FUJINO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E78-A   No.10   pp.1350-1354
Publication Date: 1995/10/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Analog Signal Processing
electronic circuits,  switched-current,  auto-tuning filter,  analog signal processing,  

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In this paper, a new switched-current auto-tuning filter is proposed. Switched-current (SI) is a current-mode analog sampled-data circuit technique. 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 amplifier) integrators. The gain of an SI-OTA integrator can be electronically controlled by the bias current. The proposed filter is a current controlled filter (CCF) and a PLL technique was used as its tuning method. A 2nd-order SI auto-tuning low-pass filter with 100kHz cutoff frequency was designed assuming a 2µm CMOS process. The characteristics of this SI filter and its tuning characteristics were confirmed by SPICE simulations.