Design of Field-programmable Operational Transresistance Amplifier using Floating-gate MOSFETs

摘要

We propose a comprehensive design procedure to design Field-programmable/Reconfigurable Analog Integrated CMOS circuits. Instead of repeatedly iterative simulation steps to achieve desired design specifications by fine tuning the W/L ratios of the FETs, we use first order classroom equations to achieve central value of desired specifications and then execute a customized fine tuning of specifications to the customers requirement with the help of Floating-gate Transistors FGMOS. To demonstrate the proposed design cycle, a modified high frequency/RF Operational Transresistance Amplifier (OTRA) CMOS circuit is designed where transresistance gain and input output low impedances are programmable, independently to desired values within a specific field range, using FGMOSs. In FGMOS the programmable charge at floating-gate using external voltages can results in threshold voltage field-programming, which in turn program the design (OTRA) specifications. With specific sizing and biasing condition, the transresistance can be programmed from 0.5kohm to 6kohm, input and output impedance from 600ohm to 10Kohm, while offset current can also be compensated independently using respective FGMOSs with 13-bit programming precision. However the final circuit, with four FGMOS occupies 75μm × 64μm chip area. The design also consumes less power, total power consumption is about 3.96mW and show good thermal stability as output voltage variation with temperature is about 25μV/°C.