一种适用于GSM/WCDMA的中频滤波器

采用SMIC0.35μmCMOS混合信号工艺,实现了同时适用于GSM/WCDMA的四阶有源RC低通中频滤波器(LPF)。该LPF具有高线性度,同时满足GSM和WCDMA的带宽性能,并且在两种模式下有元件最大的共享度。芯片面积大约1578μm×515μm。为了优化GSM模式下的功耗,运放的带宽做成可调。为了消除温度和工艺等外界因素的影响,采用电容阵列调节滤波器的转角频率以及频响曲线。同时,两种模式下的电容阵列做成部分共用的形式,减少了电阻的使用。测量得到的噪声系数在GSM和WCDMA模式下分别为56dB以及43dB。在WCDMA模式下,IIP3测量得到34dBm,功耗为17.9mW;在GSM模式下,功耗为11.3mW。电源电压为3.3V。

An IF Filter for GSM and WCDMA

Based on SMIC 0.35 μm mixed signal process,a forth-order active-opamp RC lowpass filter used in GSM/WCDMA communication system is presented.The filter meets the bandwidth specifications of the PDC and WCDMA standards especially the high IIP3,and shares the maximum number of components between the two modes.The total area is 1 578 μm×515 μm.The operational amplifiers with adjustable GBW were used to optimize GSM-mode power consumption.The capacitance matrix was used to tune the cutoff frequency with the consideration of the varieties of the temperature and technology.Also,the capacitances were made partially overlaping to reduce the resistance spread.The measured noise figure is 56 dB and 43 dB in the GSM and WCDMA modes,respectively.In the WCDMA mode,the IIP3 is 34 dBm,and the power dissipation is 17.9 mW;While in the GSM mode,the circuit consumes 11.3 mW.The supply volatge is 3.3 V.