Programmable circuits for analog matrix computations.

Matrix operations are at the core of signal processing in radiofrequency and microwave networks. While analog matrix computations can dramatically speed up signal processing in multiport networks, they can also reduce the size, weight, and power of radiofrequency and microwave devices by partially eliminating the need for power-hungry electronics. These computing devices exploit fundamental properties of electromagnetic waves, enabling parallel signal processing at the speed of light. Here, we propose and demonstrate a microwave-integrated circuit capable of implementing universal unitary matrix transformations. The proposed device operates by alternating non-reconfigurable and reconfigurable layers of basic RF components, comprising cascaded power dividers and programmable phase elements, respectively. The controllable multipath interference through conjunctive use of linear wave mixing with active phase control enables creating complex transformations in this device. We experimentally demonstrate this device concept using a four-port integrated circuit operating across the frequency range of 1.5-3.0 GHz and at hundreds of micro-Watt power levels. The proposed device can pave the way for universal analog radiofrequency and microwave processors and preprocessors with programmable functionalities for multipurpose applications in advanced communications and radar systems.