The Research And Design Of CMOS High Gain Wide Bandwidth Operational Transconductance Amplifier

With the wide application of IC products to all aspects of civilian and military fields, people also constantly improve the requirement for the performance of the integrated circuit. Operational amplifier is one of units of analog integrated circuits which is widely used.It is not only used for signal computing, processing, transform and generating circuit, but also used in switching circuit. The performance of operational amplifier will directly affect the performance of analog integrated circuit system, and the more serious will limit system performance improvements. Operational transconductance amplifier (OTA) is a kind of operational amplifiers without buffer output. It gets more commonly used in analog integrated circuits. Therefore, OTA becomes a hot research topic in the field of microelectronics.The purpose of the article is to give an in-depth study and design for voltage reference and operational transconductance amplifier. In this paper, the main work includes:(1)In order to solve the problem of the high-power, large area traditional reference consisting of BJT transistor, a correcting ultra low power voltage reference with power on reset (POR), by introducing the MOS tube of working in the sub-threshold region and digital trimming technology, is proposed. It provides a stable reference voltage reference for OTA in the circuit. Compared with traditional voltage reference, the proposed voltage reference has the advantages of the low temperature drift correction and low power consumption.(2) A novel single-ended output operational transconductance amplifier with high and variable gain, by introducing the current multiplication and distribution technology, is proposed to solve the problem of obtaining high and tunable gain operational amplifier in a low voltage and deep sub-micron process. Through theoretical analysis and simulation verification of the circuit, the results show that, the design OTA gets a DC open loop tunable gain from 61dB to 91dB, the maximum static power consumption of 434uW, the minimum common mode rejection ratio of 114dB, the proposed OTA has the advantages of high and variable gain. Moreover, according to the study of op-amp gain and bandwidth, a high gain wide bandwidth fully differential operational transconductance amplifier by introducing the load transistor division, high-speed current mirror, gain boosted technique and so on, is proposed, which solves the problem of limited gain and bandwidth for cascode structure.Through theoretical analysis and simulation verification of the circuit, the results show that, the differential OTA obtains a DC open loop gain of 105.4dB, unit gain bandwidth of 714MHz, phase margin of 84.5°, common mode rejection ratio of 136dB, the equivalent input reference noise of 6.17nV/sqrt(Hz) at 1 MHz. The OTA realizes double transconductance, and has high output impedance, gain and wider bandwidth characteristics.(3) According to the study of sampling circuit and filter circuit, the design’s OTA is implemented the application and simulation in the 12 bit 100MHz sampling circuit for pipeline ADC and multiple-feedback second order filter circuit, their performance indicators reaches the design requirements. Lastly, this paper completes the layout design for the voltage reference, single-ended output OTA, fully differential output OTA, sampling circuit and multiple-feedback second order filter circuit.