Layout-Configurable and Low-Loss Impedance Matching Circuits Built of Slim CMOS Transmission Lines

Using slim on-chip transmission lines of a compact multi-metallization structure, millimeter-wave impedance matching circuits are constructed by two open stubs. In a typical 50-Ω system, an impedance transformation ratio of 1:5 is achieved by configuring multiple transmission line segments of 60.5 Ω, 32.5 Ω and 50 Ω in their characteristic impedance Z0. Based on a 65-nm CMOS process, the design gives an insertion loss of 1.0 dB at 60 GHz, according to 3D electromagnetic simulation. The reflection loss is also fairly low with |S11| ≈ -16 dB. The low-loss impedance transformer has a broad bandwidth of 25.6 GHz for |S11| < -10 dB. The bandwidth is also broad in a simple quarter-wavelength transformer but with about 1.4 dB insertion loss. With its compact structure, the layout of the transmission line segments can be easily configured to fit the floor-planning of a millimeter-wave integrated circuit, occupying a minimal chip area (< 17 μm in width).