The current popular Internet of Things is driving the rapid development of short-range wireless communication,making low-power wireless communication terminals become a research issue.With the advancement of CMOS technology,low power consumption design by reducing the supply voltage has become the most direct and effective way.As an important module of the wireless communication receiver,the programmable gain amplifier is responsible for adjusting the gain.Therefore,research on the low-voltage programmable gain amplifier has important significance.In order to solve the problem that the gain of the programmable gain amplifier under low voltage changed drastically across the variation of process,voltage and temperature,which decreased the demodulation performance of the receiver.A coarse gain stage circuit based on global master-slave control which had anti-PVT characteristics was designed.The master circuit of the coarse gain stage selected a resistor self-biased differential amplifier,which had a simple structure and low power consumption.Constructing a transconductance related to the reciprocal of the resistance by transconductance automatic adjustment unit to convert the gain into a ratio of two resistors.The slave circuit of coarse gain stage replicated the master circuit,achieving perfect anti-PVT characteristic under low voltage.It had the advantage of low power when cascading in multiple stages compared with the super source follower scheme.The circuit of output voltage adjusted adaptively was designed to ensure the normal operation of the error detection amplifier at low voltage.The transconductance-transimpedance gain fine-tuning stage was improved,and meanwhile adopted the Class-AB output stage to improve the driving capability.The master-slave structure adaptive tail current source was used widely in the entire design to alleviate the need for voltage margin,meanwhile it also provided a high common mode rejection ratio.After the verification of simulation,the tape-out and test was done.The test result showed the low-voltage anti-PVT programmable gain amplifier can achieve gain amplification and adjustment function at 0.7V.It could provide gain control range from 12d B to 60 d B with the step of 2d B,causing a gain error of 1.05d B.The sensitivity of the overall receiver chain was-95d Bm.The PGA met the requirement for application.In order to solve the problem of large gain error in the test,and to improve the anti-PVT capability of AC coupling,the design of the cascade circuit was optimized.The traditional miller capacitive negative feedback DCOC was improved.The simulation result showed that the gain of the coarse stage gain amplifier adopting the modified negative DCOC changed only 0.723d B across the process variation.The improved overall programmable gain amplifier consumed 0.71m W at 0.7V supply voltage.The ability to suppress low frequency small signal reached-45d B.The upper limit frequency f _Hof-0.5d B bandwidth reached 4.75MHz,lower limit frequency f _Lwas 341k Hz.Meanwhile the anti-PVT capability was improved,the bandwidth was further expanded. |