A Novel Active Inductor Based on Double Gyration Loop and Noise Suppression Branch
A novel active inductor is proposed,which is mainly composed of a first gyration loop,a second gyration loop and a noise sup-pression branch.In the first gyration loop,both adjustable feedback resistance and cascade transistor are employed to increase Q value.Furthermore,three external tuning terminal voltages in the first gyration loop are jointly tuned to compensate the changes of L value and Q peak due to the variation of frequency.In the second gyration loop,the transistors in the second negative transconductor are configured as common source-common gate structure to not only further improve the Q value,but also realize the independent adjustment of Q value relative to L value by adjusting external tuning terminal voltage of common gate transistor.The introduction of noise suppression branch can reduce simultaneously the noises of both the first rotation loop and the second rotation loop,and thus reduce the noise of the active inductor.Finally,by the deep cooperation among the two gyration loops,their external tuning terminals and the noise suppression branch,the active inductor can achieve three excellent performances,i.e.the L value and high Q peak can remain almost unchanged at different frequencies,the Q value can be tuned independently in a wide range with respect to the inductance value,and the noise can be obtained at different frequencies to achieve low values.The results showed that the active inductor achieves high Q peaks of 4 971,4 977 and 5 027 with the variation of only 1.12%at 8.4 GHz,9.35 GHz and 10 GHz respectively,meanwhile,the corresponding induct-ances are 3.39 nH,3.37 nH and 3.13 nH with the variation of only 7.98%.At high frequency of 9.85 GHz,the Q peak can be tuned from 1 489 to 23 735 with the regulation rate of as high as 176.3%,while the variation of inductance is only 0.012%.The noise is 4.18 nV/√Hz at 1 GHz and 1.99 nV/√Hz at 5 GHz.
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