Microwave Field-Effect Transistors - 1976

Concurrent multiband low-noise amplifiers-theory, design, and applications

“…In the seventies, breakthroughs in the development of field-effect transistors (FETs) (e.g., GaAs MESFET) led to higher gain and lower NF than bipolar transistors for the frequencies in the range of several gigahertz [10]. Currently, advanced FETs and bipolar transistors still compete for lower NF and higher gain at frequencies in excess of 100 GHz.…”

“…1) Higher carrier mobility and peak drift velocity result in a higher transistor transconductance and shorter carrier transit time [10] for a given current, thus allowing for the reduction of the dc current for the same transconductance (gain) in transistors which lowers the input-referred noise and, hence, the NF. This gives compound semiconductors a significant advantage over silicon, as for instance, the electron mobility and the peak drift velocity are typically six and two times larger, respectively, for GaAs when compared to silicon [10].…”

“…This gives compound semiconductors a significant advantage over silicon, as for instance, the electron mobility and the peak drift velocity are typically six and two times larger, respectively, for GaAs when compared to silicon [10]. 2) Higher carrier mobility also results in lower parasitic drain and source series resistors.…”

“…Also, it is noteworthy that the noise of the equivalent channel resistance 10 in series with at high frequencies is already taken into account in the gate- 10 It should be noted that this channel resistance is different from r of MOS transistor in the linear (ohmic) region. induced noise expressions in (10).…”

“…Some authors (e.g., [56]) consider the channel resistance noiseless while others (e.g., [25]) modeled it as a noisy resistor. However, it should be noted that channel resistance and gate-induced noise originate from the same distributed gate effect (or nonquasi-static effect) in MOS transistors and the complete noise expressions similar to (10) should be used [50]. Although its noise is already taken into account, channel resistance will affect the expressions for input matching and should be considered in the design process [57], [56].…”