SiGe Direct Up-converter with above 30 dB Single Sideband Suppression from 18 to 39 GHz

A miniature 0.13 μm silicon germanium (SiGe) direct up-converter is presented that is suitable for use in multi-channel systems such as phased-arrays that apply digital beamforming. The circuit has a measured up-converting single-sideband suppression above 30 dB across a broad operating bandwidth from 18 to 39 GHz. The architecture for the oscillator path includes a frequency tripler with transformer-based coupling, a three-stage polyphase filter, and differential buffers. The circuit novelty is the layout construction method with a custom library of parameterised cells (pcells) to obtain a high degree of parasitic symmetry. Measurements were performed using a vector network analyser and an arbitrary waveform generator for the Inphase (I) and Quadrature (Q) baseband inputs. The sideband suppression in the up-conversion process is compared favourably to previously published results for broadband frequency converters that utilise low intermediate frequency (IF) inputs.