Yosuke Miyoshi

A 1.4-dB-NF variable-gain LNA with continuous control for 2-GHz-band mobile phones using InGaP emitter HBTs

We designed a continuously variable-gain low-noise-amplifier (VG-LNA) circuit with a noise figure (NF) of 1.4 dB. This VG-LNA has a diode-loaded emitter follower and a variable-current source. The diode-loaded emitter follower enables gain control without NF degradation at the maximum gain; the variable-current source improves the linearity and widens the range of gain control. It was fabricated by using InGaP-emitter heterojunction bipolar transistors (HBTs) and has an NF of 1.4 dB at maximum gain, 1.95 GHz, and a 3-V supply voltage. Its maximum gain is 15 dB, its input 3rd-order-intercept-point (IIP3) at the maximum gain is 3.4 dBm, and the gain-control range is 40 dB. The obtained of NP of 1.4 dB is the lowest so far reported for a continuously controlled VG-LNA.

Charge-trapping defects in Cat-CVD silicon nitride films

We show that Cat-CVD silicon nitride films contain more than 10 19 cm -3 nitrogen-bonded Si dangling bonds, similarly to the case for conventional CVD films. However, the charge-trapping behavior of the Cat-CVD films is found to be quite different, in spite of the same origin for the dominant defects. The difference is ascribed to a non-uniform distribution of defects that is strongly depleted near the surface in Cat-CVD films.

High power AlGaAs/GaAs HBTs for Ka-band operation

AlGaAs/GaAs power HBTs have been developed for operation in the 26 GHz band. The HBTs were designed for improved thermal stability and power gain. A common-base HBT with a 480-/spl mu/m/sup 2/ emitter area achieved a 0.65 W CW output power with 34% collector efficiency, 16% power-added efficiency, and 6 dB linear power gain at 26.85 GHz. A 960-/spl mu/m/sup 2/ CB HBT produced an output power of 0.8 W with 5.6 dB linear power gain at 26.2 GHz.