Bluetooth is a new wireless standard that uses short-range radio links to replace the cables connecting portable and/or fixed electronic devices. The standard defines a uniform structure for a wide range of devices to communicate with each other. The goal of Bluetooth transceivers is to achieve robustness, low complexity, low power and low cost....[ Read more ]

Bluetooth is a new wireless standard that uses short-range radio links to replace the cables connecting portable and/or fixed electronic devices. The standard defines a uniform structure for a wide range of devices to communicate with each other. The goal of Bluetooth transceivers is to achieve robustness, low complexity, low power and low cost.

Conventional monolithic frequency synthesizer is difficult to fulfil the Bluetooth specifications. Traditional designs usually generate a 2.4-GHz signal using LC-oscillators with on-chip spiral inductors. These inductors have low quality factors, occupy a large chip area, and are quite sensitive to process variation, which degrade the performance in terms of cost, power and production yield.

This thesis presents a 1.8-V 2.4-GHz monolithic CMOS inductor-less frequency synthesizer that meets all the Bluetooth specifications. The design employs a fractional-N architecture with a novel frequency doubler to achieve a 2.4GHz operating frequency. Because the oscillating frequency is half, a ring oscillator can be used to replace the LC-oscillator to achieve wide tuning range with a minimum chip area. In addition, the complexity and the requirement of other building blocks, likes frequency divider and multi-modulus divider can be relaxed.

Implemented in a 0.35μm CMOS process and measured at a 1.8V voltage supply, the results can meet all the requirements of Bluetooth specification. Operating at 2.45GHz, the design consumes 58mW and achieves a phase noise of -92.5dBc/Hz@500kHz with a tuning range of 12%. The settling time is 55μs and the core chip area is 0.69mm².