X-Band MMIC amplifier on GaAs/Si

A single-stage MMIC feedback amplifier fabricated on GaAs epitaxially grown on high-resistivity Si (6 × 10
³
Ω.cm) will be described. The GaAs active and buffer layers were grown on 4°-off-(100) high-resistivity Si substrate by organometallic chemical vapor deposition. The peakc arrier density was 1.7 × 10
¹⁷
cm
^-3
and the electron mobility was near 2900 cm
²
/V·s. The amplifier had 5.5-dB maximum small-signal gain and a 3-dB bandwidth of 8.5-11.5 GHz. The performance was limited by the poor quality of the Schottky harrier on GaAs/Si. The thermal resistance of the MESFET in this MMIC was measured and found to be lower than that for a comparable unit on a semi-insulating GaAs substrate by 18°C mm/W.