SAW-less低噪声射频发射机前端关键技术研究

在一个移动终端集成多种通信模式已经成为重要趋势。然而，片外声表面波滤波器（SAW）通常被用于射频发射机前端，来保障接收机噪声系数不受发射机输出噪声的影响。SAW滤波器价格昂贵且占用较大面积，因此无声表面波滤波器（SAW-less）射频前端成为研究热点。本项目围绕着SAW-less低噪声发射机前端展开研究，并深入分析了发射机输出噪声过高的原因，同时兼顾线性度及功耗等指标，设计出新型SAW-less低噪声发射机前端。通过采用无源增益N通道滤波调制器，实现了对低通滤波器、混频器及本振（LO）分频器的噪声抑制。此外，N通道滤波调制器的中心频率可调性使得单片集成多模多标准发射机的研究更进一步。采用多栅极线性化AB类功放（PA）驱动器，在高效率前提下实现了对CIM3非线性项的有效抑制。设计的SAW-less低噪声发射机前端将在65纳米CMOS工艺下流片验证，为产业化应用提供有效解决方案。

With the development of mobile communication techniques, it becomes an important trend to support multi-mode multi-standard communications in a mobile terminal. However, off-chip SAW filters are always used in radio-frequency (RF) transmitter front-end to guarantee the noise figure performance of receiver is not affected by the output noise of transmitter. Thus, SAW-less RF front-end is becoming a popular direction due to that SAW filters are not only expensive but occupy large area. This project presents a SAW-less low-noise RF transmitter front-end, that achieves balanced performance on output noise, linearity and power consumption. The low output noise of the transmitter is achieved by analyzing the noise contribution in both system- and module-level. In the transmitter, the passive-gain N-path filtering modulator is employed to suppress the noise of baseband low-pass filter, mixer and LO generator. Besides, the LO-defined center frequency in N-path filtering modulator promotes the research on multi-mode multi-standard transmitter in a single chip with a further progress. By exploiting the multi-gate linearization technique, the class-AB power amplifier (PA) driver achieves high attenuation on CIM3 term，also with high power efficiency。The SAW-less low-noise RF transmitter front-end will be fabricated in 65nm CMOS technology and verified by the measurement results, which provides an effective solution for industrialization.