A high DC gain self-cascode structure of operational transconductance amplifier (OTA) design with bandwidth enhancement is proposed. Based on the concept of self-cascode structure, which provides high output resistance and transconductance, the proposed OTA presents a compensation methodology to obtain better unity-gain bandwidth. The proposed OTA is compared with previous structures, with the same size of input/output transistors and compensation capacitance as well as load capacitance, and simulation results show a DC gain enhancement of >20% and 2.4 times unity-gain bandwidth at the same time, and the performances of the proposed OTA bring a better figure of merit (FOM).

In this study, the investigation into X-ray radiation of VDMOS is described. A radiation test of VDMOS was made by X-ray at various loads. The different radiation behavior of VDMOS was observed. The "rebound" of the threshold voltage shift of VDMOS at a larger load with X-ray radiation was larger than that without X-ray radiation, indicating that a radiation annealing effect happened to VDMOS at a powerful load. In terms of transconductance, all the radiated samples showed an increase in interface traps (Qit). At 9.84 X 105rad (Si), the interface traps increments at a large load and at a small load were 6. 3 X 10n/cm2 and 5. 12 X 10n/cm2, respectively. A timely annealing effect is a major factor contributing to the "rebound" of the threshold voltage shift, and caused by anneal of VDMOS weak inversion interface traps whose equivalent charge is -2. 31X 10n/cm2.

An N-channel VDMOS I-V curve is measured after X-ray radiation under condition of different power dissipation. It is found that the property of new interface traps induced by X-ray radiation of self-annealing VDMOS sample does not conform to existing theory reasonably well. Based on measured data，we advance the viewpoint that the interface trap has current conductive property besides being charged up, and the conduction is assumed to be the generation or recombination current caused by new interface traps, which can not be simply identified quantitatively from the I-V curve.