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This work consists in the design of a CMOS Voltage Reference Source with a temperature coefficient inferior to 50 ppm/ C. This voltage source should be applied in radio frequency receptor/transmitter but can be also applied in any analog system. The technology employed in the design is the CMOS 0 .35 μm from the AMS (Austria Micro Systems) with four metal levels and two poly-silicon levels. The implemented voltage source is of the Bandgap t ype and uses MOS devices in weak inversion, a parasitic bipolar tran sistor, and resistors made with high resistive poly-silicon. The circuit produces a PTAT (Proportional to Absolute Temperature ) voltage that is added to the bipolar transistor b ase-emitter voltage to build an output voltage independent of temperature. The project and the drawing of the layout of the ci rcuit had been carried out. The netlists of the circuit were generated from the layout and they were employed in simulations done with the software ELDO and the BSI M3v3 MOS model, in typical, worst speed, and worst power conditions. Through th ese simulations it was verified that the circuit reached the initial specifications . The value of the output voltage, however, although being next to the desired value o f 1.25 V, varied with the employed simulation conditions. Two different Bandgap circuits had been sent to the foundry: a circuit with integrated resistors (dimensions of 220 μm x 76 μm) and another one without the resistors (dimensions of 190 μm x 36 μm). This last one allows, with the adjustment of external resistor values, modifying, if necessar y, the operation conditions of the circuit. The circuits had been characterized and th e circuit with integrated resistors has a temperature coefficient inferior to 40 ppm/oC , an output variation rate with the power supply close to 19 mV/V. The output voltage v alue at 50 oC is between 1.1835 V and 1.2559 V (1.25 V ± 67 mV). The circuit withou t the resistors has a temperature coefficient as high as 90 ppm/oC, an ou tput variation rate with the power supply inferior to 28 mV/V. The output voltage valu e at 50 oC is between 1.247 V and 1.2588 V (1.25 V ± 9 mV). The temperature range us d in the measurements was from -30 oC to 100 oC.

Projeto de circuitos para geração de tensão de referência em sistemas receptores/transmissores RF.