Ultra-Low-Noise PTAT Sensors and Bandgap Regulators

Adaptalog's low-noise techniques are of benefit both for PTAT current sources and for Voltage references and regulators.

Depending on the technology, our PTAT current sources can provide practical noise reductions of 4-dB compared with Widlar-style PTAT sources in the same technology.  This low noise level is achieved with a beta-compensated design, allowing the intrinsic temperature-linearity of the PTAT to be maintained. 
N.B. that in many applications reduced requirements from the support circuitry can result in the effective advantage being rather greater than the

When applied to Voltage references and regulators, our techniques allow practical noise reductions of 11-dB – and the sensitivity to beta is again rather small.

We also have IP for reference/regulator arrangements that are compatible with most CMOS technologies.  Compared with the Brokaw-derived arrangement which is usually regarded as suitable for C-MOS references, our arrangement provides a noise advantage of around 7-dB; sensitivity both to beta and to substrate currents is again very small.

The effects of flicker noise are also appreciably attenuated in our designs; in some cases, the advantage can be more than 20-dB compared with a Brokaw reference.

Table 1 compares the performance of some low-drop-out regulators using Adaptalog's proprietary techniques.  Multiple versions are given to illustrate the robustness of the designs when optimised against different parameters.
Also listed are two quasi-LDO regulators; these are included to illustrate the performance of the PTAT current generator cells.