一种46 MHz Gm-C复数滤波器及其自动频率调谐电路设计

A Design of 46 MHz Gm-C Complex Filter and Automatic Frequency Tuning Circuit

基于0.18μm CMOS工艺,设计了一款高频Gm-C复数滤波器,该滤波器的中心频率达到46MHz,在20MHz的通带内的平坦度小于0.36dB,能够实现98dB的镜像抑制,以及28dB的带外抑制.滤波器工作在1.8V电源电压下,消耗的电流小于7.9mA.为了纠正滤波器的频率,提出了一种基于积分器和数字电路的频率调谐方法,该调谐电路在调谐完成后会自动关闭,实现了'零功耗',特别适合低功耗的应用.仿真结果表明调谐误差小于±1.5%.

A high frequency complex Gm-C filter was proposed by using 0. 18 μm CMOS RF process. The filter has 20 MHz bandwidth and is centered at 46 MHz, while the pass-band flatness is less than 0. 36 dB. The image band rejection is higher than 98 dB, and the out-band rejection is higher than 28 dB. The complete filter consumes less than 7.9 mA with 1.8 V supply voltage. An integrator with digital circuits based frequency tuning circuit was used to real ize the automatic tuning of both center frequency and band-width. On the completion of the tuning, the circuit will automatically shut down. The ‘zero power＇ is particularly suitable for low power applications. Simulation results show that the tuning error is less than ±l. 5 %.