Design Of Analog Transmitting Terminal In Amr System Based On PLC

With the high-speed development of internet technology, electric power industry is moving forward in recent years. However, the existing electricity management and statistical means are not economic and comprehensive, including electric card prepaid system, hand-held meter reading computer and remote wireless meter reading. Power line carrier communication(PLC) comes into people’s horizons as an alternative means. Taking low power line as communication medium, has advantages such as high mechanical strength, good reliability and widely distributed, will bring considerable economic value to electric power enterprises. Most of chips in auto meter reading system based on PLC are foreign products nowadays, increasing economic pressure to customer and electric power enterprise as well as bring security risks in power system to our country.In this paper, according to the requirement of the subject, basic principles of PLC meter reading has analyzed, the sender blocks and analog circuits including DAC, filter and line driver has been researched and designed. Work in this paper based on SMIC 0.18μm 1P6 M CMOS process. 10 bit sectional current steering DAC is used to convert digital signals into analog signals, post simulation results of dynamic parameters are SNDR = 61.3 dB,SNR =61.55 dB,THD =-74 d B, SFDR = 76.35 d B, ENOB = 9.89 bit, Static parameters of the differential output are DNL = 0.18719 LSB, INL = 0.17187 LSB. Third-order Chebyshev type 2 low-pass filter has been used to make analog signal in DAC filtering and smoothing. The low-frequency gain is-765 md B, cutoff frequency is 521 KHz@3 dB, the initial frequency of stopband attenuation is 803 KHz, stopband attenuation of-20.9 dB. And through composed of preamplifier and driver stage line driver circuit to swing to harmonic power amplifier output signal, in the conditions that the load is as low as a few ohms, the single-ended output swing is 2 V, when the maximum output current is 600 mA, total harmonic distortion is less than 60 d B. The above indicators suggest that the designed transmitting terminal not only achieve D/A conversion, low pass filter and power amplification, but also ensure the signal pathway with a good linearity. Finally, layout of transmitting terminal has been done. Current steering DAC and the power MOSFET in driver has been careful layout.