MULTI—DRIVE BANDWIDTH EXTENDED STACKED AMPLIFIER IN SIGE:C130 NM BICMOS TECHNOLOGY

Abstract

A multi—drive broadband stacked distributed amplifier along with simulations and design in SiGe:C BiCMOS 130nm technology, has been presented in this work. The proposed multi—drive stacked distributed amplifier (MD—SDDA) consists of four devices implemented in a unit—stack topology. The unit—stack utilizes multi—drive technique by coupling the signal from previous unit—stack to the base of common—base device of the next unit—stack. Additionally, the top most device in the unit—stack is deployed as cascode to mitigate the stability issue arising from the forward coupling between inter—stacks. There are three unit—stacks implemented in a uniform distributed topology out of which two unit—stacks employ multi—drive technique. The device sizes are kept same to increase the impedance moving up in the stack and to ease the device biasing. Small—signal simulations of the proposed MD—SDDA design demonstrate 135THz of Gain—bandwidth product (GBW) with 20 dB gain. The average group delay is ±10 psec with a variation of ±3.5 psec throughout the entire operating band stating the effectiveness of proposed design for a broadband signal. Total harmonic distortion (THD) of 5% at output power of 16 dBm identifies the suitability of the approach for higher modulation formats towards realizing data rates as high as 800 Gbps. Lastly, the proposed MD—SDDA is compared with a conventional stacked distributed amplifier (SDDA) under the same number of unit—stacks, devices in the unit—stacks, and DC bias conditions. The proposed MD—SDDA yields superior gain—bandwidth product of 135 THz as compared to 109 THz for a conventional SDDA.