GaAs heterojunction bipolar transistor MMIC DC to 10 GHz direct-coupled feedback amplifier

A DC-to-10-GHz fixed-gain amplifier implemented with a GaAs heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) technology is described. The wideband amplifier design is based on Darlington-connected transistors with resistive feedback. A 3- mu m-emitter self-aligned-base ohmic metal HBT IC process (f/sub max/ approximately=30-40 GHz) with a simplified MBE growth structure is used to fabricate the amplifier. The feedback amplifier exhibits a flat 11-dB gain response to 6 GHz with a -3-dB roll-off at 10 GHz, 5-6-dB noise figure over the 10-GHz band, and 1-dB power compression of 11 dBm at midband. Compared to similar 0.5- mu m-gate GaAs MESFET wideband amplifiers, the HBT's third-order intercept point (IP3)/DC power ratio is two times greater and the chip size seven times smaller. Compared to similar advanced silicon bipolar and previously reported HBT direct-coupled amplifier designs, the GaAs HBT amplifier reported has twice the bandwidth.<
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