Design And Analysis Of A Low Power Auto-Gain Control Ask Signal Amplifier

In recent years, with increasing demand for implantable medicalequipments, portable electronics and TPMS system, amplifiers which can beused in sensors of low-power chips are given more and more concerns. In thiscondition, we start the project to develop a low-power auto-gain control ASKsignal amplifier. It can be applied to the front-end signal receivers incommunication equipments. It is specially designed to battery-poweredenvironment, with a wide supply voltage range, so as to increase theutilization and life of the battery.The design can operate reliably in the temperature ranging from-40centigrade degree to100centigrade degree and supply voltage ranging from2.5V to5V. The500mA·h lithium cell in the inside tire circuit of tire pressuremonitoring system (TPMS) can supply power for the system for5to7years.Low power consumption is achieved in two ways. One is the front signalreceiving circuit of the MOS transistor operates in the sub-threshold region soas to reduce the operating current and power consumption. Because the stagecircuit must always be in an open state. Since the voltage range of the sub-threshold region is very narrow, ensuring its front stage circuit to work inthe different supply voltages and at different temperatures within thesub-threshold is the key technology of the present design. The other is twomodes of operation dominated by Sleep-Wake up mechanism. In sleep mode,only the level amplifiers circuit, the signal converter and the mode selectioncircuit are working, the remaining parts of the circuit are not working. Untilthe mode selection circuit issued excitation signal did the entire chip convertfrom sleep mode to working mode. After that, all functional parts startworking.The thesis designed functional circuits such as reference circuit, systemworking mode selection circuit, signal amplitude regulation circuit, levelamplifiers circuit, system control circuit. The design can receive sinusoidalsignal with a carrier frequency of125KHz modulated by ASK (amplitudeshift keying modulation), and then amplify the signal with controllable gain,and outputs the signal after the processing. The power consumption of thedesign under general environment in sleep mode is3.22μW, in working modeis5.6μW. In the range of working environment, the lowest powerconsumption is1.53μW, and the highest power consumption is only12.55μW.