0.5 V Fully Differential Universal Filter Based on Multiple Input OTAs

Winai Jaikla,Tomasz Kulej,Fabian Khateb,Peerawut Suwanjan,Rajeev Kumar Ranjan,Montree Kumngern

doi:10.1109/access.2020.3030239

Abstract

The design of a low-power, low-voltage, fully-differential universal biquad filter is presented in this work, which is constructed from four multiple-input gate-driven operational transconductance amplifiers (MI-OTAs) along with one passive resistor and two passive capacitors. The scheme of presented biquad filter has three high-input impedance voltage nodes and single output voltage node. Five unity gain filtering functions, all-pass (AP), low-pass (LP), band-pass (BP), high-pass (HP) and band-stop (BS) responses, are obtained. The selection of output filtering responses is obtained without the need of component matching condition, inverting or double input voltage. With this feature, it can be easily controlled with digital programming. The quality factor (Q) and angular frequency (ω <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) are electronically and independently tuned. Moreover, the adjustment of ω <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and Q can be done without affecting the voltage gain. A workability of the design is confirmed via Cadence software and the Spectre simulator based on the 180 nm TSMC CMOS technology parameters. The proposed fully differential filter operates with 0.5 V supply voltage. The results verify that the proposed filter dissipates the total power of 53.3 nW. Additionally, the dynamic range (DR) of band-pass filtering function is 63 dB for 2% third intermodulation distortion (IMD). Also, the simulated RMS value of the band-pass filtering noise is 45μV.

Highlights

Analog active filters are necessary in many fields of analog signal processing systems for examples sound systems, control systems, communication systems, instrumentation etc
The universal filter proposed in this work is based on multiple-input operational transconductance amplifier (OTA) (MI-OTAs), that allows simplifying its overall structure and improve the dynamic range (DR)
From Eq (3) the small-signal transconductance of the MIMOST from i-th input is given by: gmi where gm=ID/npUT is the transconductance of internal MOS. As it can be concluded from the above considerations, the Multiple-Input MOS transistor (MI-MOST) is a multiple-input device, where the transconductance seen from i-th input is attenuated by the factor of C /Cin

Summary

INTRODUCTION

Analog active filters are necessary in many fields of analog signal processing systems for examples sound systems, control systems, communication systems, instrumentation etc. The use of single-ended active devices to realize the analog filter limits the dynamic range With this limitation, the fully differential filters have been introduced to amend the analog active filtering performance. The improvement of dynamic range and the fully differential filter gives many advantage features such as improving interference rejection and supply noise reduction or lower harmonic distortion. It can reduce the coupling influence between various blocks [9, 10]. The simulation results with Cadence software and the Spectre simulator verify the performance of the design

Multiple-input CMOS OTA

Proposed Fully Differential Universal Biquad Filter Using Multiple Input OTAs

SIMULATION RESULTS

COMPARISON TABLE

CONCLUSION