Ultrawideband Front-End Circuits and 6-32 GHz Phased-Array Beamformer for Tri-Band SATCOM

The demand for communications is increasing and this requires higher data transmission and better global coverage. Wideband circuits enable high data rate communications for wireless and wireline applications. Also, they simplify the hardware by replacing several circuits or systems covering narrower bandwidths. This thesis presents three different wideband designs addressing wideband circuits and systems. The circuits presented in this thesis are all implemented using 90 nm SiGe BiCMOS process.Firstly, a 10-110 GHz low noise amplifier is presented. The circuit is composed of four differential cascode stages. The measured small-signal gain is 19-24.5 dB with a noise figure of 4.8-5.3 dB. Highest figure of merit is achieved with conventional cascode amplifier topology. The circuit is very small compared to the distributed amplifier designs in the literature and consumes less power. Second, a 10-130 GHz distributed power amplifier (DPA) is presented. The circuit is composed of three stages each with multiple cascode amplifier sections. The amplifier achieves small-signal gain of 18-23 dB at 10-30 GHz and increasing to 33 dB at 98 GHz, resulting in a record gain-bandwidth product of 2.6 THz. The circuit has a peak output 1-dB compression point (OP1dB) of 13.1 dBm at 22 GHz. The proposed amplifier achieves the largest gain-bandwidth product in SiGe DPAs while providing relatively high power. Finally, an 8-channel 5-33 GHz transmit phased array RFIC for C, X, Ku and Ka-band SATCOM applications is presented. The 4×2 beamformer is implemented in a 90nm SiGe HBT process. Each channel has a wideband two-stage power-amplifier (PA), a phase-shifter (PS), a variable gain amplifier (VGA) and single-ended to differential converter (S2D). The input RF power is distributed to the 8-channels using a two-stage lumped-element Wilkinson network and active dividers. The measured electronic gain is 24-27 dB at 5-33 GHz with 5-bit phase-shifter operation and >20 dB gain control. A peak OP1dB and OPsat of 10.8-14 dBm is achieved over the entire frequency range. The chip is then implemented in a wideband phased-array using tapered-slot (Vivaldi) antennas. The 16-element phased array achieves ±60° scanning at C, X and Ku bands and ±30° scanning at Ka band with a broadside EIRP of 16-38.5 dBm at 8-32 GHz. QPSK, 8 PSK and 16-QAM waveform are delivered to the phased array for performance evaluation, and <4-4.8% EVM is achieved C to Ka-band at P1dB (EIRP) operation. Application areas are C/X/Ku/Ka-band ground terminals for satellite communications