In Razavi's book, Figure 11.20 -----Generation of a temperature-independent voltage.
The configuration has Q1,Q2,Q3 pnp transistors.
As described in bandgap circuit design,the two pnp transistors ratio usually equal 8:1,so when doing layout,we can place the pnp transistors like the following,
A A A
A B A
A A A
But in Figure 11.20, if Q1:Q2:Q3=1:8:1,that is total 10 pnp transistors,how will you place these 10 pnp transistors?
The best way is to take 2 dummy pnps and u can plase in 3*4 or 4*3 array.There is one more best way is take 6 dymmys and place 4*4 u can get beat matching and can minimize the stress and temperature effects to aa greater exteny.