Design of a PLL with improved locking range and its biomedical applications |
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Authors: | B. Chakraborty |
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Affiliation: | Department of Physics and Technophysics , Vidyasagar University , Midnapore, 721 102, West Bengal, India |
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Abstract: | This paper describes a phase locked loop employing a low voltage VCO using modified ECL inverter cells. The VCO circuit employed, features a positive feed back scheme to improve the operating frequency. The phase detector used in the PLL also uses a positive feedback scheme to improve the locked range and to reduce supply voltage of operation of the entire circuit. An improvement of locked range of around 35% was obtained from circuit simulation (using PSPICE) as well as from practical circuit, using discrete components. The minimum supply voltage required here is 2.5 volts. Some biomedical applications of this PLL are also proposed. |
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Keywords: | Voltage controlled oscillator (VCO) Current controlled oscillator (CCO) Emitter couple logic (ECL) Phase locked loop (PLL) Low pass filter (LPF) Phase detector (PD) Optical coherence tomography (OCT) |
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