A two-dimensional direct-coupled standing-wave oscillator array

This paper presents a 2-D direct-coupled standing-wave oscillator (SWO) array implemented in a 90nm CMOS technology with 61.5GHz oscillation frequency. The SWO array can provide synchronous signals with identical frequencies, amplitudes, and phases at multiple locations over a chip. The reported SWO array is a reticular structure in a plane, and therefore it can be extended in two dimensions periodically in a CMOS process. Wireless measurement is a feasible solution to verify the synchronicity of the reported 2-D SWO at mm-wave regime. A mm-wave radiator which consists of the proposed SWO array, an RF driver array, and an on-chip loop antenna array is implemented in a single chip for wireless measurement purpose. The indirect evidence of synchronicity is provided from the correlation between the wireless measured effective isotropic radiated power (EIRP) and phase noise of 1 × 1, 2 × 2, and 3 × 3 arrays. The experimental and theoretical results are matched. The EIRP in the normal direction of the array is increasing by a factor of 10 log N² and the phase noise at 1MHz offset is reducing by a factor of 10 log N over that of a single cell, where N is the number of unit cells in the array.