Title
Analog Filter Design Using Ring Oscillator Integrators
Abstract
Integrators are key building blocks in many analog signal processing circuits and systems. The DC gain of conventional opamp-RC or Gm- C integrators is severely limited by the gain of operational transconductance amplifier (OTA) used to implement them. Process scaling reduces transistor output resistance, which further exacerbates this issue. We propose applying ring oscillator integrators (ROIs) in the design of high order analog filters. ROIs implemented with simple CMOS inverters achieve infinite DC gain at low supply voltages independent of transistor non-idealities and imperfections such as finite output impedance. Consequently, ROIs scale more effectively into newer processes. A prototype fourth order filter designed using the ROIs was fabricated in 90 nm CMOS and occupies an area of 0.29 mm2. Operating with a 0.55 V supply, the filter consumes 2.9 mW power and achieves bandwidth of 7 MHz, SNR of 61.4 dB, SFDR of 67.6 dB and THD of 60.1 dB. The measured IM3 obtained by feeding two tones at 1 MHz and 2 MHz is 63.4 dB.
Year
DOI
Venue
2012
10.1109/JSSC.2012.2225738
Solid-State Circuits, IEEE Journal of
Keywords
Field
DocType
CMOS analogue integrated circuits,analogue integrated circuits,integrated circuit design,invertors,operational amplifiers,radiofrequency amplifiers,radiofrequency oscillators,CMOS inverters,Gm-C integrators,OTA,ROI,SFDR,SNR,THD,analog filter design,analog signal processing circuits,bandwidth 7 MHz,fourth order filter design,frequency 1 MHz,frequency 2 MHz,infinite DC gain,opamp-RC,operational transconductance amplifier,ring oscillator integrators,size 90 nm,supply voltages,transistor nonidealities,transistor output resistance,Analog filters,analog signal processing,continuous time filters,integrator,low voltage,ring oscillator,ring oscillator integrator
Output impedance,Ring oscillator,Total harmonic distortion,Computer science,Control theory,Operational transconductance amplifier,Electronic engineering,CMOS,Analogue filter,Electrical engineering,Analog signal processing,Operational amplifier
Journal
Volume
Issue
ISSN
47
12
0018-9200
Citations 
PageRank 
References 
16
1.05
2
Authors
3
Name
Order
Citations
PageRank
Brian Drost1161.05
Mrunmay Talegaonkar2161.05
Pavan Kumar Hanumolu324027.03