A 5µW fractional CMOS bandgap voltage and current reference

Design of a sub-1V, low power, fractional bandgap voltage reference (V
r
∼ 0.6V) conjoined with a current reference (I
r
∼ 1µA) in standard 90 nm digital CMOS is proposed, utilizing standard parasitic substrate PNPs. A positive temperature coefficient (TC) voltage is generated across a feed-back resistor, R
f
, via a negative TC emitter-base voltage (V
EB
) on one side of R
f
and the looped-back V
r
output on the other side, which has a near zero TC. The resulting current, I
x
= (V
r
− V
EB
) /R
f
, has a zero current crossing point that can be set roughly around the mid-point of minimum and maximum operating temperatures. As such, I
x
supplies the needed positive TC current to the bandgap's proportional to absolute temperature (PTAT) current loop that facilitates generating the residual zero TC current, I
r
, which is concurrently fed to R
o
to produce V
r
. Simulations show V
r
of about 0.6V at TC of about ±10ppm/°C (with trim) can be achieved over span of −50°C < T < 150°C. Accordingly, simulating for bandgap's operation for +0.9V > V
DD
> +5V, indicates that I
DD
of about 5µA, and voltage coefficient (VC) of about ±50 ppm/V are achievable.