Investigation of Compact Power Amplifier Cells at THz Frequencies using InGaAs mHEMT Technology

Broadband 300-GHz Power Amplifier MMICs in InGaAs mHEMT Technology

“…The output power per required chip width of 67 mW/mm is improved by a factor of four compared to previously published cascode topologies in this mHEMT technology [24]. Since the output stage with two 8-finger CS devices in parallel does not require a larger chip width than the 8-finger cascode gain stages, the output power per required chip width is significantly increased compared to the results presented in [11], achieving approximately 5-dB more output power by doubling the required chip width of the PA core.…”

“…TFMSL wiring permits a compact matching network implementation and the accurate in-phase matching of parallelized multifinger devices in close proximity, realizing broadband PA MMICs with reduced chip width. These advantages of using thin benzocyclobutene (BCB) layers for TFMSL wiring has been described and investigated for GaAs pHEMT [18] and InP HEMT [19], [20] technologies as well as this InGaAs mHEMT technology [11], [21], [22] in detail previously.…”

“…8. The amplifier topology of the UA was developed based on the four-stage amplifier MMIC reported in [11], including optimized matching networks, as well as an additional CS output stage with two parallel 8 × 16 µm CS devices. The 8-finger cascode devices in the input stages are implemented to provide high gain, while the CS transistors in the output stage permit the maximization of the total gate width in the output stage, increasing the achievable output power at the given chip size.…”

“…Due to their most simple and symmetric device layout, 2-finger HEMT devices typically provide the largest bandwidths and transistor models with the best accuracy, compared to multifinger devices. This advantage of 2-finger devices was discussed in detail for this InGaAs mHEMT technology in [11]. The 2-finger transistor models, which are used to model the multifinger devices, are based on a multiport modeling approach with an electrical equivalent circuit model of the extrinsic transistor shell, which is based on the actual structure and layout of the transistor [33].…”

“…In comparison, over the frequency band of 200-350 GHz, the highest output power levels have been reported by solid-state power amplifier (SSPA) millimeter-wave monolithic integrated circuits (MMICs) realized in InP HBT and InP HEMT technologies [5]- [10] biased at 1.8-2.2 V. In [5], 17-24-dBm output power was reported between 180-265 GHz and at a narrow frequency band around 300 GHz, up to 13.5 dBm has been demonstrated in [7], both using a 250 nm InP HBT technology. Broadband InGaAs mHEMT based SSPA MMICs, on the other hand, have reported up to 6.8-8.6-dBm of output power over the 280-320-GHz frequency band in [11].…”