Creating Vref in an IC

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jaydnul

Joined Apr 2, 2015
152
Do most IC designs use zener diodes to create a reference voltage (say 5.1V) when they have a Vcc that could be within a wide range of values? Or is there a way to create a constant voltage regardless of source voltage using standard component design?
 

OBW0549

Joined Mar 2, 2015
3,566
Do most IC designs use zener diodes to create a reference voltage (say 5.1V) when they have a Vcc that could be within a wide range of values? Or is there a way to create a constant voltage regardless of source voltage using standard component design?
Zeners are rarely (if ever) used as voltage references in modern ICs; most use a bandgap reference instead. Google the term and you'll find plenty of info.
 

WBahn

Joined Mar 31, 2012
26,280
Making zeners in an IC is generally not an option and, if it were, would require extra processing steps which means extra cost. Furthermore, the accuracy and stability of a zener reference isn't good enough for many applications. Instead, you want something that can be fabricated using just the normal processing steps and bandgap references fit this bill; this is true even on a CMOS IC despite being based on bipolar transistors because you can make lateral BJT transistors of one flavor even in a standard purely CMOS process. The downside is that they are physically large (in IC-scale structures) for low noise and they tend to be power hogs (in CMOS-scale terms). You can't have it all.
 

hp1729

Joined Nov 23, 2015
2,304
Do most IC designs use zener diodes to create a reference voltage (say 5.1V) when they have a Vcc that could be within a wide range of values? Or is there a way to create a constant voltage regardless of source voltage using standard component design?
It may be presented in the schematic as a Zener but it really isn't.
What voltage did you need? How stable? For high stability there are voltage references with built-in heaters to keep the reference at a constant temperature.
 

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