An Ultra Compact Millimeter-Wave VCO in 3-D IC Technology

In this letter, an ultra compact three-dimensional (3-D) voltage-controlled oscillator (VCO) is presented. By utilizing the through silicon via (TSV) as inductors and variable bridge topology in the LC tank, the core area of VCO is reduced significantly with an improved tuning range. Implemented in a standard 90 nm CMOS process, the VCO consists of the top and bottom layers connected by TSVs using an in-house developed 3-D IC technology. The VCO is capable of operating at 43.3-43.9 GHz with a footprint of 0.0022 mm³, and a core area of only 0.007 mm² which is about one to two orders of magnitude smaller than that in previous works. The measured phase noise is -90.8 dBc/Hz (1 MHz offset) at 43.3 GHz with an output power of -12.6 dBm. Under a supply voltage of 1.2 V, the VCO consumes a dc current of 15.4 mA.