Do you have a product in mind already? Or are you exclusively interested in any product that provides an extended temperature range? For the Quark SoC X1000 series, there are several chips available and 4 of them provided extended temperature ranges. Check the table below:
Quark SoC X1000 Quark SoC X1001 Quark SoC X1010 Quark SoC X1011 Quark SoC X1020 Quark SoC X1020D Quark SoC X1021 Quark SoC X1021D Quark Microcontroller D2000 Operating Temperature 0°C to 70°C -40°C to 85°C 0°C to 70°C -40°C to 85°C 0°C to 70°C 0°C to 70°C -40°C to 85°C -40°C to 85°C -40°C to 85°C
The Quark SoC X1000 Series and the Quark Microcontroller D2000 are very similar, however the first presents a Simplified system design and BOM optimization, this means that there’s a high degree of integration of various inputs/outputs and acceleration functionality. In the other hand, the D2000 is suitable for smart tags, display controllers, etc. All this information can be found in the Product Brief of each product.
The files above are the ‘Product brief’ for both products, I believe you’ll get a much more clear idea after reading their specifications and intended uses.
Regarding the reference designs that you request, check the following links to see the schematics.
Quark SoC X1000 series: Schematics
Quark Microcontoller D2000: Schematics
X1001, X1011, X1021, X1021D, D2000 are what I'm interested in.