SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

422 CHAPTER 8. FIELD EFFECT TRANSISTORS

a)

b)









 





















Figure 8.46: Push-pull amplifiers realized using (a) non-complementary devices, and b) comple-
mentary (CMOS) devices

Table 8.2: Typical power obtainable from various device technologies driving aZo= 50Ωload.
device typical typical typical device typical
technology Vbr Vk IDSS periphery Pout,max
(V) (V) (mA/mm) (mm) (W)
GaAs MESFET 20 1 300 600 200
§InP PHEMT 12 1 500 0.45 0.3
†GaN HEMT 150 5 1000 57.6 500
§HRL,†CREE

1. Class-A mode of operation is desired when requirements of linearity and bandwidth have
   to be simultaneously satisfied


2. Push-pull class - AB/B operation is attractive if complementary devices. are available such
   as CMOS


3. designs must be for at least 10 dB gain to ensure highPAE.


4. circuits must use a device technology with highfτVbrproduct.

8.10 PROBLEMS ....................................

• Section 8.2
  Problem 8.1Discuss the reasons why one needs a large Schottky barrier value for the gate
  inaMESFET.