Multichannel monolithic front-end system design Part II. Microwave bipolar-JFET process for low-noise charge-sensitive preamplifiers

New monolithic low-noise process has been developed for simultaneous fabrication of high-speed low-noise 4-terminal and 3-terminal pJFETs and microwave low-noise npn BJTs. A new ion-implanted 4-terminal structure of JFET having 300 MHz cut-off frequency is designed. The process provides direct contact to a top gate and independent access to the top and bottom gates. Application of p-channel implant makes it possible to optimize the JFET pinch-off voltage without deterioration of bipolar transistor characteristics: fT ≥ 3 GHz, current gain β ≥ 150, Rbb′ ≤ 15–40 Ω.