Analytical Model of the Linearity of a Cryogenic Bipolar Analog Multiplier

This paper studies the nonlinear behavior of a Gilbert cell multiplier. The investigation has been carried out by means of mathematical modeling and Cadence circuit simulations at room and cryogenic temperatures. The circuit has been implemented in the 130 nm SiGe BiCMOS SG13G2 technology by Innovations for High Performance (IHP) Microelectronics (Frankfurt am Oder, Germany). In addition, a similar investigation has been carried out for a Jones modulator. The comparison demonstrated that the Gilbert cell multiplier exhibits better spectral purity, especially at cryogenic temperatures. This suggests the Gilbert multiplier as a promising mixer for quantum computing control circuits, where spectral purity is critical for the quantum gate fidelity.