A low-power and ultra-compact W-band transmitter front-end in 90 nm SiGe BiCMOS technology

This paper presents a W-band direct-conversion transmitter front-end implemented in SiGe BiCMOS technology. The transmitter consists of an up-conversion mixer, a power amplifier (PA), and all the required on-chip passive matching networks. A differential cascode structure with capacitive neutralization is used in the PA design for improved gain and reverse isolation. W-band on-chip transformers are extensively utilized to realize low-loss and ultra-compact passive matching networks. This design strategy enables the whole transmitter core to fit within a 600 μm × 250 μm die area. The transmitter achieves +7.2 dBm peak output power and 18 dB conversion gain at 87 GHz, with 73.5 mW total power consumption. Modulation tests with QPSK and 16QAM signals (both at 50 MSym/s) were also performed. Average EVM values of 5.9% / 6.7% have been achieved at 7 dB output power back-off for QPSK/16QAM signals, respectively.