Design and evaluation of a Ka-Band Colpitts VCO for wireless communications
Abstract (Summary)Inspired by the success of the Colpitts oscillator at low frequencies, the design and performance of a Ka-Band Colpitts VCO is evaluated. The Colpitts VCO is a 300 pm x 600 /cm MMIC and uses a Norte1 HBT. Lumped elements are used, in fact the HBT is de-stabilized by exploiting the parasitics of a spiral inductor. Operating within the HBT thermal consuaints, the Colpitts VCO delivers -0.9'2dBm at 33.83GH2, and is tuned 82 MHz using the collector bias. The phase noise is -32.4 dBc/Hz at a carrier offset of 100 KHz. The measured performance variation from both circuit and electromagnetic simulations is evaluated, and the discrepancies explained. Indeed, individual sections of the Colpitts VCO are measured and evaluated, yielding further insight. Moreover, the large signal design procedure is evaluated and compared to other possible design approaches. Potential application of the Colpitts VCO to wireless communications, such as LMCS, is assessed.
Source Type:Master's Thesis
Date of Publication:01/01/1998