A Highly Linear Dual Stage Amplifier with Beyond 1.75 THz Gain-Bandwidth-Product

This work reports a multi-purpose highly linear ultra-wideband amplifier with a gain bandwidth product (GBP) of 1.75 THz, the highest reported in any MMIC process. A transimpedance amplifier is cascaded with a distributed amplifier, emulating a receiver subsystem. Using a diamond heat spreader, to dissipate heat from transistors, the cascaded amplification subsystem can achieve very high OIP3 from 20 to 24 dBm when measured between 5 to 65 GHz. A small signal average gain of 24 dB is observed over a frequency range exceeding the maximum measurable bandwidth from DC to 110 GHz. Compared with other ultra-wideband MMIC amplifiers beyond 110 GHz bandwidth, the circuit offers a unique combination of high linearity (OIP3) and high gain. As a result, the cascaded amplifier is suitable for applications in optical-electrical converters, spectroscopy and ultrawideband measurement systems in the sub-THz frequency range.