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A Versatile Technique for Linearly Tunable Transconductors. George Raikos and Spyridon Vlassis Electronics Laboratory Physics Department University of Patras http://www.ellab.physics.upatras.gr. Introduction. Based on master-slave approach. Advantages :
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A Versatile Technique for Linearly TunableTransconductors George Raikos and SpyridonVlassis Electronics Laboratory Physics Department University of Patras http://www.ellab.physics.upatras.gr
Introduction • Based on master-slave approach • Advantages : • Linear tuning of input transconductance • Wide tuning range • Stability over PVT corners • Circuit simplicity
Principle of operation • Master transconductor: • Slave transconductor:
Conventional differential pair • Disadvantages : • Dependency on process/temperature variations • Dependency on bias conditions • Inability for linear transconductance tuning
Proposed structure • Cooperates master and slave diff. pair • Node k IR–ITUNE • IR=Itune (due to negative feedback loop) • VR=50 mV • VCM=900 mV
Proposed structure • Master transconductor : • Slave transconductor: • VR=50 mV • VCM=900 mV
Proposed structure • Thus for slave transconductor: • is linearly tuned • is independent of process, temperature and supply voltage variations • (W/L)d.p.=20μm/0.3μm • VR=50 mV • VCM=900 mV • m=5
Voltage generator • Provides VCM+1/2 VR and VCM-1/2 VR • Benefits : • Master and slave diff. pair share the same input common mode voltage • Master tracks the bias conditions of slave diff. pair • RG=2.5kΩ • R=1kΩ • C=1pF
Simulations Results • Technology : standard 0.18um CMOS • VDD =1.8V • Simulation tools : • Monte Carlo tool • PVT corners tool
Simulations Results • gm,in,slave – ITUNE for PVT corners • Worst case (PVT) for gm,in,slave was 3.5% • Linear tuning of gm,in,slave • Worst case (PVT) linearity error 3% for ITUNE 0.1μΑto 10μΑ
Noise analysis (*) Without the proposed technique
Conclusions • A versatile technique for linearly tunabletranscoductors was introduced • The input gm controlled through a DC current • Advantages : • Linear tunability of input gm • Wide range of tuning • Stability over process/temperature/voltage supply variations • Circuit simplicity
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