Low-power Charge-pump Based Switched-capacitor Circuits

In this thesis, low-power charge-pump (CP) based switched-capacitor (SC) circuits are proposed. The approach is validated in SC integrators and gain stages, and is shown to achieve power savings compared to conventional SC circuits. For the same thermal noise and settling performance, a CP based integrator with N sampling capacitors ideally consumes N^2 times lower OTA power compared to a conventional integrator. Practical effects such as the OTA partial slew-rate limitation and the CP parasitics reduce the power savings. In the case of a SC gain stage, reduction in power savings also occurs due to the load capacitance from the next stage. A prototype delta-sigma modulator employing a CP integrator at the front-end is fabricated. Experimental results demonstrate that the CP based ADC achieves the same performance as a conventional ADC while consuming three times lower OTA power in the front-end integrator. The CP ADC achieves 87.8 dB SNDR 89.2 dB SNR and 90 dB DR over a 10 kHz bandwidth while consuming 148 uW from a 1.2 V power supply. The conventional ADC has similar performance but dissipates 241 uW. The CP ADC figure-of-merit (FOM) is 0.369 pJ/conv-step, which is almost 40% lower than that of the conventional ADC.Ph

Study the effect of 3,4-Methylenedioxy methamphetamine on cytochrome P450 2E1 activity

Evaluating the effects of ecstasy on CYP2E1 activity is of great concern, mainly due to growing trends in abuse and co-administration of MDMA with ethanol and the dominant role of this isoenzyme on ethanol metabolism. This study aimed to evaluate the effects of MDMA on CYP2E1 activity. A total of 24 male rats were selected and divided into three groups. The first and second groups consisted of 12 rats and were employed to optimize the perfusion method, and the third group was employed for studying the alteration of CYP2E1 activity after liver exposure to MDMA (300 and 600 ng/ml). The amount of chlorzoxazone and 6-hydroxy chlorzoxazone in a sample obtained from liver perfusion before and after exposure to a buffer containing MDMA was determined by HPLC-FL. The enzymatic activity of rat CYP2E1 decreased after liver perfusion with a buffer containing 600 ng/ml of MDMA. However, no significant changes were observed in chlorzoxazone and 6-hydroxy chlorzoxazone concentration in perfusate before and after liver perfusion with a buffer containing 300 ng/ml of MDMA. Our findings suggest that the activity of CYP2E1 in rats might decrease only after administration of MDMA at a lethal dose. However, further animal and human studies are needed to confirm our assumption