Researchers from the College of Electronic and Optical Engineering at Nanjing University of Posts and Telecommunications (NJUPT) in Nanjing, China, have designed, fabricated and measured a single-pole single-throw (SPST) RF switch built on an RRAM process. The switch operates across the DC-Ku band with a measured insertion loss below 1 dB, and it holds its state without any standing bias.
RF switches sit in the front-end of nearly every wireless system, routing signals between transmit and receive paths. The standard options used today, field-effect transistors, PIN diodes and RF MEMS, all share a drawback: they need a continuous bias voltage or drive current to stay in either the ON or the OFF state. Over long operating periods that translates into meaningful static power draw and thermal management headaches, which is exactly the wrong trade-off for battery-powered IoT nodes and wearables.
The researchers explain that because RRAM's resistive switching is non-volatile, an RRAM-based switch can be flipped between its low-resistance (ON) and high-resistance (OFF) states with a nanosecond-scale electrical pulse and then left alone - it consumes no holding energy at all. The NJUPT team describes this as a "write-and-hold" characteristic, and it is the central argument for using a memristive device where a transistor would normally sit. RRAM also brings fast read/write, high storage density and CMOS process compatibility, so the switch can in principle be integrated alongside conventional front-end circuitry.
The key design innovation reported in the paper is a tapered ground structure in the coplanar waveguide layout surrounding the RRAM cell. Isolation is typically the weak point of two-terminal memristive switches, since the OFF-state high-resistance path is shunted by parasitic capacitance and inductance in the electrode stack. Reshaping the ground plane improves the isolation figure without degrading the ON-state loss.
The team developed and fabricated the RRAM cell, and test showed insertion loss of less than 1 dB across the full DC-Ku band, measured at 0.851 dB at 18 GHz, isolation exceeding 7.5 dB and non-volatile state retention with zero holding power. The low insertion loss at 18 GHz, combined with the zero-static-power operation, makes the approach interesting for duty-cycled systems where the switch spends most of its life in a fixed state and the energy budget matters more than deep isolation - reconfigurable antennas, phase shifters, and IoT and wearable radios among them.