There are widespread shortages of electronics parts at the moment, especially passives. Quoted factory lead times are 40 weeks or thereabouts, and since the industry is capacity-limited, it isn't clear that the situation is going to get better any time soon, so everybody's starting to panic. Given all this churn I've been spending an unconscionable amount of time lately finding suitable replacements for out-of-stock parts.
From the cutting room floor at Building Electro-Optical Systems, Third Edition:
Measuring temperature is surprisingly subtle. There are lots of sensors out there; Digikey sells thermistor sensors interchangeable to +- 0.1 C from several vendors for about $3 in onesies. IC sensors tout good accuracy and linearity, and come in both analogue and digital versions for way under a buck. So what's the issue?
Decap picture of a Terabeam CD3109 APD/TIA module, taken with a lens glued to a cell