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NTSC Video Sync Separator and A Gm-C Anti-Aliasing Filter Design with Digitally Tunable Bandwidth for DVB-T ReceiversHung, Chien-Chih 24 June 2005 (has links)
The first topic of this thesis is a novel NTSC video sync separator (NSS) with a high-PSR (power supply rejection) bias generation circuitry (BGC) comprising a temperature compensation circuitry. The proposed BGC is composed of step-down regulators and a bandgap-based bias with cascode current control. The clamping voltages required for sync separation from an NTSC signal are generated.
The second topic is a temperature-compensated 6th order transconductance-C (Gm-C) anti-aliasing filter (AAF) with digitally tunable bandwidth which can be applied in the analog front-end circuit of DVB-T receivers. The proposed AAF is controlled by digital signals to provide three different baseband bandwidth (6, 7, 8 MHz) selection. A regulator with a bandgap circuitry supplies a stable voltage to suppress the variations of power and temperature. Moreover, a temperature -compensated circuitry is used to neutralize bandwidth drifting caused by the temperature variation. The bandwidth accuracy of the proposed design verified by HSPICE post-layout simulations is better than 3.28% at every PVT (process, supply voltage, temperature) corner. It is adequate for the DVB-T receivers¡¦ baseband processing.
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Low-Variation 1 MHz Clock Generator,High Sensitivity Linear Voltage-to-Frequency Converter,and High-PSR Bias Circuit for NTSC SYNC SeparationLee, Tzung-Je 13 July 2004 (has links)
This thesis includes three topics. The first topic is a low-variation 1 MHz clock generator. The second one is a high sensitivity linear voltage-to-frequency converter. The last one is a high-PSR bias circuit for NTSC SYNC separation. All of the circuits can be applied to related consumer electronic products.
The low-variation 1 MHz clock generator includes a bias circuit which automatically compensates the drifting caused by temperature variations. Furthermore, the circuit contains neither BJTs nor diodes to reduce the area cost. The frequency variation is measured to be less than 2.55\% in the range of 0¢J~90¢J.
The high sensitivity linear voltage-to-frequency converter is mainly constructed by a window comparator[11]. We analyze and improve the performance of accuracy to achieve both high accuracy and high sensitivity. The accuracy error is less than 1% and sensitivity is 84 KHz/V in the voltage range of 0.1V~0.8V.
The high-PSR bias circuit for NTSC SYNC Separation is implemented by a bandgap reference which is controlled by a feedback loop to reduce the interference of the environment. The measurement variation of the bandgap reference is less than 1\% when the variation of power supply is 10\%. The sensitivity of the bandgap reference to temperature is measured to be 0.0006V/¢J.
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