Engineering research in quantum computing is geared towards building a ”useful” quantum computer; usefulness here refers to the capability of solving computation problems that hold significant value in commercial applications, but are currently impossible to do in reasonable time-frames using classical algorithms. This is fundamentally a problem of scale – problems that can be solved by few-qubit processors can also be readily simulated by classical supercomputers in realistic time-frames, but as these problems grow in complexity, quantum computers are believed to be able to provide an exponential speedup over their classical counterparts, the so-called quantum advantage. However, scaling quantum computers presents many challenges due to the need to perform complex signal control and data processing at nanosecond time scales on fragile quantum systems that need stringent degrees of isolation from the environment for the computations to be carried out with high fidelity. Some of the most promising implementations of experimental-grade quantum computers are maintained in cryogenic environments due to the fact that at low enough temperatures noise processes due to random thermal excitations can be minimized. However, the control and measurement of quantum processors is currently done by systems at room temperature, whose connections to the cryogenic environment present thermal loading that will need to be addressed as these processors scale and their IO requirements to co-processors grow in complexity. As such, one possible path to scaling co-processing capabilities without compromising the quantum processor’s performance is the partial or complete integration of the co-processor in the cryo-environment. Several works describe systems that aim to do just that; and ”Cryo-CMOS” has become an important research subspace. This thesis aims to add to the current advancements in this field, specifically in the area of qubit measurements. It culminates in the implementation of a radio receiver that leverages the advantages of BiCMOS technology in cryo-environments to measure the state of a superconducting transmon-based qubit while strapped to a 4K stage in a dilution refrigerator. Critically, we demonstrate that low-noise amplification, down-conversion, and demodulation can all be done in the cryo-environment on a constrained power budget, with high fidelity comparable to a state-of-the-art (InP-HEMT LNA-based) qubit readout system, when preceded by a high-gain, quantum-noise-limited Josephson parametric amplifier.