Design of a low phase noise LO module for IEEE 802.11ac system
The design of a low-phase-noise local oscillator (LO) module for RF transceivers which support the very high throughput mode of IEEE 802.11ac standard is presented in this paper. This LO module provides both intermediate frequency (IF) LO and radio frequency (RF) LO by using HMC83x series chips. Low pass filters and amplifiers are used to improve output power and suppress harmonics of LO signals. Experimental results show that the designed LO module can generate IF LO signal at 1.05GHz and RF LO signal at a range from 4GHz to 5GHz with 20MHz step. The measured in-band phase noise is -116.14dBc/Hz for 1.05GHz carriers and out-of-band phase noise is -142.51dBc/Hz at 1MHz offset. As to RF LO, the measured in-band phase noise is below 107.48dBc/Hz at 10 KHz offset and out-of-band phase noise is below -132dBc/Hz in a range from 4GHz to 5GHz.