一种2～4GHz宽带接收机的小型化前端设计

Small Front-end Design of a 2 ~ 4 GHz Wideband Receiver

针对2~4 GHz的超宽频带,提出了一种宽带接收机的前端设计方法,其中包括射频信道设计、频率合成器的设计以及基带电路设计。鉴于小型化的设计思想,射频前端采用零中频接收机的架构,使用LTCC滤波器实现噪声系数优于8 d B,输出三阶截断点优于27 d Bm（低噪声模式下）。频率合成器采用集成VCO的锁相环芯片ADF4351,实现单边带相位噪声优于-110 d Bc/Hz@200 k Hz。基带电路采用正交解调器ADL5380和12位双通道AD转换器AD9238,可实现带宽为20 MHz的I/Q双路同时解调。通过FPGA或DSP处理,可广泛用于便携式小型化的监测接收机或通信接收机。

For ultra-wideband of 2 ~ 4 GHz,a method of wideband receiver front-end design is proposed,which includes RF channel design,frequency synthesizer design and baseband circuit design. Given the small size of the design,the RF front-end adopts a zeroIF receiver architecture,uses LTCC filters to realize a noise figure of better than 8 d B,and achieves an output of third-order intercept point better than 27 d Bm（ low-noise mode）. The frequency synthesizer adopts a VCO integrated PLL chip ADF4351,realizing a SSB phase noise better than-110 d Bc / Hz @ 200 k Hz,and the scanning speed is better than 40 GHz / s. The baseband circuit uses an ADL5380 quadrature demodulator and a 12-bit dual-channel AD converter AD9238,which achieves 20 MHz-bandwidth simultaneous I /Q dual demodulation. By FPGA or DSP processing,it can be widely used in portable miniaturized monitoring receivers or communications receivers.