Research And Application Of Low Voltage CMOS Variable Gain Operational Transconductance Amplifier

Integrated circuits are a cutting-edge discipline in the field of electronics and communications.All countries in the world are investing huge human and financial resources to promote the development of integrated circuit industry.As the mobile consumer electronics to meet the requirements of the performance of the circuit power integration is higher and higher.And other aspects of the increasingly high demand,semiconductor integrated circuits is the rapid development.Operational Transconductance Amplifiers are one of the most versatile units in analog integrated circuits and have been of great concern in recent years.They can be used not only for analog signal processing,processing,transformation,but also directly used in the switch circuit,its performance is a direct impact on the performance of the entire analog integrated circuits.This paper is mainly for the transconductance operational amplifier for the research,designand application.The main work of this paper includes:(1)Based on the principle of the basic transconductance op amp,the circuit structure of the existing CMOS transconductance op amp is introduced concisely.On this basis,the low voltage variable gain transconductance operational amplifier is proposed.The circuit is improved from three aspects to the existing transconductance op amp,specifically using the signal attenuation technique at the input stage to improve the linearity of the circuit;use the more accurate current mirror structure to reduce the circuit error;The super-cascaded cascode structure is used at the output stage to boost the gain of the circuit.The simulation results show that the DC open-loop gain of the OTA is adjustable from 53dB to 68dB,the static power consumption is540?W,the unit gain bandwidth is 68MHz to 79MHz,the equivalent input noise at 1MHz is 29nV/?kHzto 32nV/?kHz,in the case of a power supply voltage of ± 0.8 V,the linear interval is± 0.55 V,the whole transconductance amplifier has the characteristics of low power supply low voltage,adjustable gain,large unit gain bandwidth,high linearity and low power consumption.(2)Based on the low-voltage CMOS adjustable gain transconductance operational amplifier designed in this paper,the voltage-mode three-terminal input single-ended output OTA-C multi-function filter is used.The circuit structure of this filter is composed of only three OTA and two capacitors,the circuit structure is simple,without changing the circuit structure of the main circumstances,only need to change the input voltage combination can be completed low-pass,high-pass;band-pass.Filtering function conversion,has a very good practical significance.(3)In the case of the completion of the filter design is also based on the design of the OTA circuit designed a ring oscillator.The entire oscillator circuit consists of five cascaded OTA and two analog resistors.The circuit structure is simple,the layout area is small,easy to integrate on the chip,and can adjust the OTA gain to control the oscillator frequency the frequence is djustable from 50MHz to 62.5MHz.(4)According to the layout design rules,the CMOS low voltage variable gain transconductance operational amplifier is designed and the post-simulation design is carried out.The circuit structure associated with this article has applied for two national patents.