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

This work reports a multipurpose highly linear ultrawideband amplifier with a gain-bandwidth product (GBP) of 1.75 THz, the highest reported in any monolithic microwave integrated circuit (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 output third-order-intercept point (OIP3) from 20 to 24 dBm when measured between 5 and 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 ultrawideband 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 subterahertz frequency range.