This paper deals with recent achievements in the field of an emerging technology termed the quantum monolithic microwave integrated circuit (QMMIC). QMMIC consists of a heterojunction interband tunneling diode and a high electron-mobility transistor monolithically integrated to obtain a new functional device. This technology enables the realization of low-voltage, high-density, and high-functionality circuits. A detailed description of the design and analysis techniques for several circuits such as an amplifier, an oscillator, and a mixer, along with the analytical treatment of the principle of operation are given in this paper. A number of prototypes implemented in InP technology constitute the proof-of-concept of the unique features of QMMIC circuit blocks for low-power wireless systems.Index Terms-Linear mixer, low power, monolithic microwave integrated circuit (MMIC), quantum-well devices, RF identification (RF ID), voltage-controlled oscillator (VCO).