A Wideband Multi-Stage Amplifier with Low Group-Delay Variation Using Transistors with Low Nodal Quality Factors in Sub-Terahertz Band

We propose a simple way to increase the bandwidth and reduce the group-delay variation of a multi-stage amplifier in the sub-terahertz range. The method is to use transistors with low nodal quality factors [3] for the amplifier. To verify the proposed method, a four-stage amplifier is fabricated using a 0.13 mu m SiGe BiCMOS process. The amplifier has the maximum gain of 5.42 dB, the 3 dB bandwidth of over 30 GHz, and the maximum group-delay variation of 12.8 ps.