Outstanding noise characteristics of SiGe:C HBT allow flexibility in high-frequency RF designs

The noise characteristics of Motorola's SiGe:C eHBT (enhanced HBT) are reported with a focus on three key frequencies, 2 GHz, 5 GHz and 24 GHz. Besides achieving extremely low minimum noise figures of 0.34 dB at 2 GHz and 2 dB at 24 GHz, key noise characteristics crucial for RF wireless designs such as noise resistance, noise matching, input and output matching, are detailed at each frequency. A simple LNA with 1 nH emitter degeneration operating at 2 GHz is demonstrated with a noise figure of 0.59 dB, maximum available gain of 16.8 dB and the amplifier is unconditionally stable. The ease in simultaneously optimizing noise, gain and input return loss at 24 GHz for emerging high-frequency RF applications is demonstrated based on measured noise characteristics.