A High IIP_3 Low Noise Amplifier for 1900 MHz Applications Using the SiGe BFP620 Transistor

摘要

Infineon's BFP620 is a high-performance, low-cost silicon germanium bipolar transistor housed in a 4-lead ultra miniature SOT-343 surface mount package. With a transition frequency (f_T) in excess of 70 GHz, this device is ideal for high performance applications, including Low Noise Amplifiers in portable telephones and other battery operated wireless communications devices. The BFP620 offers exceptionally low noise figure, high gain and high linearity at low power consumption levels. The BFP620 rivals more expensive GaAs MES-FET and PHEMT devices in performance without requiring a negative supply voltage. This application note describes a low noise figure, high 3rd-order intercept PCS band LNA targeted for 1900 MHz CDMA applications, and also provides general guidelines for improving 3rd-order intercept performance in amplifiers using Infineon transistors.