I'm designing a small PCB (max 5x5 cm) to bias and readout from an Avalanche Photodiode. Since the APD response varies greatly with the temperature, I want to use a cheap 12706 TEC together with a MAX1979 driver to achieve some kind of temperature control (0.1 is enough). However, I'm having trouble finding the best thermal pathway for the whole board - I was planning to use only one side for ICs and components, using the opposite side to place the TEC. However,
1 - Would I need to use via near the APD to conduct heat? Being a noise sensitive application, wouldn't cooled bias rails reduce signal noise?
2 - Can a thermisthor placed near the APD be enough for efficient temperature measurement? Or should I use a direct connection e.g. to the APD ground (I wouldn't want to disturbt the APD circuit)?
2 - With the number of R/Cs the layout requires, I could greatly reduce size PCB dimensions if I used a double-sided approach. Would there be any inconveninece in having the underside cooled (some rails would be cooler than others)?