Consider the single-supply bias network shown in Fig. 6.60(a). Provide a design
ID: 1932371 • Letter: C
Question
Consider the single-supply bias network shown in Fig. 6.60(a). Provide a design using a 9-V supply in which the supply voltage is equally split between RC, VCE, and RE with a collector current of 0.6 mA. The transistor beta is specified to have a minimum value of 90. Use a voltage divider current of IE/10, or slightly higher. Since a reasonable design should operate for the best transistors for which beta is very high, do your initial design with beta = infinity. Then choose suitable 5% resistors (see Appendix H), making the choice in a way that will result in a V58 that is slightly higher than the ideal value. Specify the values you have chosen for RE, RC, R1, and R2. Now, find VB, VE, VC, and IC for your final design using beta = 90.Explanation / Answer
=, IB=0, VB=VE+0.7 V=3.7 V, IEIC=0.0006 A, IR1=IE/10=0.00006 A
R1=(9-3.7)/0.0000688,333.33 , R2=3.7/0.00006=61,666.67
use R1=82,000 , R2=61,700 , VBB=9*68,000/(82,000+68,000)4.08 V
RBB=68,000*82,000/150,00037,173.33 , RE=RC=3 V/0.0006 A=5,000
use 5,100 , =90, IE=(VBB-0.7)/(RBB/(+1)+RE)=
(4.08-0.7)/(37,173.33/((90+1)+5100)0.0006136 A
VE=0.0006136*51003.13 V
VB=VE+0.7=3.83 V
VC=9-5100*0.0006*90/915.97 V