Current Sources and Voltage References

Bandgap voltage references

Characteristics of Monolithic Voltage References

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The circuit’s temperature coefficient (TC) can be determined by the following:

Figure 14.3 shows how the circuit is compensated to produce a stable output refer-

ence voltage of 1.23 volts, with a near-zero tempco. Table 14.2 shows how changing

the current-density ratio (Q

1

and Q

2

in Figure 14.2) changes the

∆

V

BE

. The current-

density ratio and the emitter area ratio are the key characteristics in the bandgap cell.

In Table 14.2, you can see that using a current-density ratio of 10:1 will produce a

∆

V

BE

of 59.17 mV, which has a corresponding tempco of 199 ...