宽频率范围的单子带压控振荡器设计

Design of a single frequency sub-band voltage-controlled oscillator with wide frequency range

基于TSMC 180 nm CMOS工艺,提出了一种振荡频率为2~3 GHz的宽频率范围、低相位噪声的单子带压控振荡器(VCO)。采用双平衡吉尔伯特混频结构,将单子带5~6 GHz压控振荡器与固定频率3 GHz压控振荡器进行下混频,可得到振荡频率为2~3 GHz的单子带压控振荡器,实现相对带宽从18.18%到40%的展宽。其中5~6 GHz单子带压控振荡器采用互补交叉耦合结构,更易达到起振条件,采用两组可变电容的并联形式以提高调谐曲线的线性度,拓宽压控振荡器的输出频率调谐范围。通过芯片测试验证,在1.8 V电源电压下,调谐电压变化范围为0.6~2.8 V时,实际输出频率范围为1.85~3 GHz,最大调谐灵敏度为1000 MHz/V,2 GHz频点处相位噪声为-123.2 dBc/Hz@1 MHz,芯片尺寸为1.2 mm×0.7 mm。

Based on TSMC 180 nm CMOS process,a single sub-band voltage-controlled oscillator(VCO)was proposed with oscillation frequency from 2 GHz to 3 GHz,which was characterized by wide frequency range and low phase noise.A double balanced Gilbert mixing structure was used to down mix a single sub-band 5-6 GHz VCO with a fixed frequency of 3 GHz VCO.Then the single sub-band VCO with an oscillating frequency from 2 GHz to 3 GHz could be obtained,which achieved a relative bandwidth broadening from 18.18%to 40%.Among them,the 5-6 GHz single sub-band VCO adopted a complementary cross coupling structure,which was easier to achieve the starting condition.Two groups of variable capacitors were used to improve the linearity of the tuning curve and broaden the tuning range of the output frequency of the VCO.The chip test verifies that when the tuning voltage varies from 0.6 V to 2.8 V at 1.8 V power supply voltage,the actual output frequency range is from 1.85 GHz to 3 GHz with maximum tuning sensitivity of 1000 MHz/V.The phase noise at 2 GHz is-123.2 dBc/Hz@1 MHz,and the total chip size is 1.2 mm×0.7 mm.