ABSTRACT
Figure 5 shows the frequency dependence of the common-emitter current gain lh2,l, Mason's unilateral gain U, and the maximum stable gain (MSG) of three parallel 0.7 x 8.5-J.tm E-up HBTs. The measurements were carried out at /c = 13 mA and VcE = 1.7 V. The!,. and fm., of the HBT with poly-GaAs reached 120 and 2300Hz, while those of the HBT without poly-GaAs reached 110 and 200 GHz. The MSG of the HBT with poly-GaAs was 1.2 dB higher than the MSG of the HBT without poly-GaAs. We attribute this increase in MSG to the reduced eTC due to complete carrier depletion in the poly-GaAs.
