Microwave noise properties of heterojunction bipolar transistors

Abstract

The broadband noise performance of silicon ger- manium (SiGe) and compound semiconductor (CS) heterojunc- tion bipolar transistors (HBTs) is presented. The key noise mechanisms in HBTs are summarized to provide a framework through which the noise limitations of the devices can be understood. Process related details and transport physics of each class of device are then compared and contrasted with a focus on details relevant to the broadband noise performance. Fundamental noise performance limitations are presented for exemplary InP/InGaAs/InP BiCMOS DHBTs and SiGe HBTs. The state-of-the-art for SiGe and CS HBTs operating in the 1- 300 GHz frequency range is reviewed and interpreted in the context of fundamental performance limitations. Finally, the paper concludes with a discussion of how the performance of future HBT technology generations should improve. Index Terms—Noise, SiGe, InP/InGaAs/InP, low noise ampli- fier, noise figure, noise measure, HBT, cryogenic Low noise amplifiers (LNAs) are critical components in a variety of systems with applications ranging from terrestrial communications to quantum computing. These devices enable the sensitive systems that permit scientists to listen to mi- crowave emissions from distant galaxies and are an essential component in nearly every radio receiver. The performance of a well designed low-noise amplifier is ultimately limited by the underlying intrinsic noise properties of the transistor technology. Therefore, decades of intense research has been focused on understanding and optimizing the noise perfor- mance of semiconductor devices. In this paper, we review the broadband 1 noise properties of silicon germanium (SiGe) and compound semiconductor (CS) heterojunction bipolar transistors (HBTs), with an emphasis on fundamental frequency and temperature dependent perfor- mance limitations as well as the requirements for improving the state of the art. The outline of the paper is as follows: 1) A review of the key sources of noise in an HBT, and how they relate to different aspects of the device. 2) A summary of the key physical factors impacting the noise performance of CS and SiGe devices. 3) A discussion of the fundamental noise limits of devices from example SiGe and CS HBT processes.