Mixed Signal Chip Design Lab Cubic Function Generator Design Boram Lee, Jaehyun Lim Department of Computer Science and Engineering The Pennsylvania State University CSE598A/EE597G Spring 2006

Mixed Signal Chip Design Lab Crystal Oscillator – f vs. T characteristic Y Z AT-cut 35¼ o -1’ 0’0’ 1’1’ 2’2’ 3’3’ 4’4’ 5’5’ 6’6’ 7’7’ 8’8’ 0’0’ 1’1’ 2’2’ 3’3’ 4’4’ 5’5’ 6’6’ 7’7’ 8’8’  Y-bar quartz Z ffff (ppm) Inflection Point

Mixed Signal Chip Design Lab Crystal Oscillator – f vs. T characteristic  XO (crystal oscillator) does not contain means for reducing the crystal’s f vs. T characteristic  OCXO (oven controlled crystal oscillator) crystal and other temperature sensitive components are in a stable oven oven temperature adjusted to the temperature where the crystal’s f vs. T has zero slope over 1000X improvement over the crystal’s f vs. T variation Large package, high power consumption – not suitable for mobile/battery powered devices  TCXO (temperature compensated crystal oscillator) temperature sensor generates a correction voltage the correction voltage applied to a variable reactance in the crystal network (ex. varactor) the reactance variations compensate for the crystal’s f vs. T characteristic about 20X improvement over the crystal’s f vs. T variation

Mixed Signal Chip Design Lab Cubic Function Generator  Application frequency compensation in TCXO Frequency / Voltage T Uncompensated crystal frequency Compensated frequency of TCXO Compensating voltage

Mixed Signal Chip Design Lab TCXO – Temperature Compensation : linear coefficient of temperature : cubic coefficient of temperature : inflection point temperature (≈ 25 °C) : actual temperature depend on cut-angle

Mixed Signal Chip Design Lab Cubic Function Generator  Design I cubic term voltage conversion circuit (Low Temperature) cubic term voltage conversion circuit (High Temperature) linear term voltage conversion circuit ∑ Cubic Wave Temperature sensor Cubic Functional Voltage Generator

Mixed Signal Chip Design Lab Cubic Function Generator  Design I out T T VgVg

Mixed Signal Chip Design Lab Cubic Function Generator  Design I out T VgVg T

Mixed Signal Chip Design Lab Cubic Function Generator  Design I out TT T T

Mixed Signal Chip Design Lab Cubic Function Generator  Design II linear inputsquare cube linear cubic wave

Mixed Signal Chip Design Lab Cubic Function Generator  Design II analog voltage multiplier analog voltage adder op-amp bias circuits

Mixed Signal Chip Design Lab Cubic Function Generator  Specification power consumption : 50 mW size : 0.3 mm x 0.3 mm supply : 5 volt single supply input range : 1.5 V ~ 3.5 V TSMC 0.35 / AMIS 0.5

Mixed Signal Chip Design Lab Cubic Function Generator  Schedule week 1 : op-amp design, test Design I week 2, 3 : multiplier design week 4, 5 : bias circuits, project progress presentation week 6 : make improvements of basic blocks week 7 : finalize of cubic function generator week 8 ~ : final revision of cubic function generator, layout, project final presentation