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We present a fully integrated 94-GHz transceiver front-end in a 130-nm/1.1-THz $f_{{{\text {max}}}}$ InP HBT process. Low power is obtained through low-voltage design and high transistor gain. The IC is designed for multi-function, dual-polarization phased arrays. At 1.5-V collector bias, in dual-polarization simultaneous receiving mode, the IC has 21-dB gain

We present a new millimeter-wave power-combining technique using transmission-line baluns which both connect transistor outputs in series and inductively tune the transistor output capacitances. The baluns are much shorter than a quarter-wavelength (λ/4), hence are more compact and have less insertion loss than a λ/4 balun. We introduce one topology providing an even number of series connections, including 2:1 and 4:1, and a second topology providing either an even or odd number of series connections. We then analyze segmented transformer power-combiners as a set of multi-conductor transmission-lines, and explore the relationship between transformer and transmission-line balun power-combiners. We demonstrate the technique with 2:1 and 4:1 series-connected designs implemented in a 0.25 μm InP HBT process. At 86 GHz, a single-stage power amplifier (PA) using the 2:1 baluns exhibits 30.4% peak PAE, 20.37 dBm output power (Pout) and 23 GHz 3-dB bandwidth from a 448 × 816 μm 2 die. A two-stage PA using the 2:1 baluns exhibits 30.2% PAE, and 23.14 dBm Pout from an 824 × 816 μm 2 die. At 81 GHz, a two-stage PA with 4:1 series output power-combining exhibits 23.4% PAE, and 26.7 dBm (470 mW) Pout from a 1,080 × 980 μm 2 die.

We report on the development of a 0.25-μm InP HBT IC technology for lower end of the THz frequency band (0.3-3 THz). Transistors demonstrate an extrapolated fmax of >;800 GHz while maintaining a common-emitter breakdown voltage (BVCEO) >;4 V. The transistors have been integrated in a full IC process that includes three-levels of interconnects, and backside processing. The technology has been utilized for key circuit building blocks (amplifiers, oscillators, frequency dividers, PLL, etc), all operating at ≥300 GHz. Next, we report a series of fundamental oscillators operating up to 0.57 THz fabricated in a 0.25-μm InP HBT technology. Oscillator designs are based on a differential series-tuned topology followed by a common-base buffer, in a fixed-frequency or varactor-tuned scheme. For ≥400 GHz designs, a subharmonic down-conversion mixer is integrated to facilitate spectrum measurement. At optimum bias, the measured output power was -6.2, -5.6, and -19.2 dBm, for 310.2-, 412.9-, and 573.1-GHz designs, respectively, with PDC ≤ 115 mW. Varactor-tuned designs demonstrated 10.6-12.3 GHz of tuning bandwidth up to 300 GHz.

We report tuned amplifiers designed for the 140-220-GHz frequency band. The amplifiers were designed in a transferred-substrate InP-based heterojunction bipolar transistor technology that enables efficient scaling of the parasitic collector-base junction capacitance. A single-stage amplifier exhibited 6.3-dB small-signal gain at 175 GHz. Three-stage amplifiers were subsequently fabricated with one design demonstrating 12.0-dB gain at 170 GHz and a second design exhibiting 8.5-dB gain at 195 GHz.