The New Warming Real-time Clock Chip Research And Design

Real Time Clock chip is one of the most commonly be used consumer electronics in our daily life. It provides people with precise real time or used in electronic system that need the real time clock chip to give time standards. At present, the clock source of Real Time Clock chip usually adopts crystal oscillator with high precision. But, because of the changing of environment temperature, the resonance frequency of the crystal oscillator circuits is variable which cause the main error of the Real Time Clock.I have designed a Crystal Oscillator circuit with the crystal which produces resonance at the frequency of 32.768 KHz based on the 0.35um process. Due to all the CMOS of the Crystal Oscillator circuits work in the sub-threshold region, greatly reduces power consumption only about 70nA. I provide a new temperature error compensating method which bases on the theory of error accumulate compensating after having a thorough research on the error source of the Real Time Clock. I have designed a saving-layout-area temperature compensation circuit which is consisted of on-chip temperature sensor circuit, temperature error calculation circuit, temperature error compensate logic circuit. It can ensure the mean inaccuracy of divided 1Hz frequency at most±5ppm. The temperature error compensation is completed fully automatically in the chip circuitry, which is not need the help of the MCU. Quartz crystal and the chip package together. Testing and trimming must be done before the chip go to customers, for the resonance frequency of the same type crystal individual difference at most±20ppm.The digital logic unit circuit is designed that based on the 0.35um process. The simulation results justify the exact logic of the carry-look ahead the adder, the subtraction, 16-bits multiplier unit circuit and other logic gates circuits.Analog and digital signal integrated circuit design of this chip use NC Verilog,Hspice,SpectreVerilog software.