The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices. We regard this NDR device as R-BJT-NDR. Comparing to the resonant tunneling diode (RTD), this novel NDR device is made of resistors and transistors. Therefore, we can fabricate this NDR device by standard Si-based CMOS or SiGe-based BiCMOS process. A circuit with two NDR. regions is obtained by combining two R-BJT-NDR devices in vertical integration. We can obtain two-peak I-V characteristics in the combined circuit. Circuit fabricated from the combination exhibits three stable operating points for frequency multiplier that can multiply the input signal frequency by three. The R-BJT-NDR device and frequency multiplier are implemented by the standard 0.35 mum SiGe BiCMOS process.