CC1101 to ESP32 – How to Connect

The "SPI" in your microcontroller stands for "Serial Perpheral Interface", which is an industry standard I/O port originally defined by Motorola. But the "SPI" in the Analog Devices' AD converter stands for "Serial Port Interface", which is not the same as the SPI in your microcontroller. It's Analog's own definition for a digital interface.

Analog has written an application notes on how to communicate with this port. It can be found here:

AN-877 Interfacing to High Speed ADCs via SPI: http://www.analog.com/static/imported-files/application_notes/56755538964965031881813AN_877.pdf

You might be able to use your microcontroller's SPI port for this, at least partly - the Atmel protocol seems at least somewhat compatible with Serial Peripheral Interface. You could connect your microcontrollers MISO port to the Atmel's SDIO port and then bit-bang the instruction header from your microcontroller to the ADC and then use the hardware SPI to read the data. Or you perhaps could connect both MOSI and MISO together in your MCU and use the pin's direction and mode bits (input-or-output, gpio-or-peripheral) to essentially disable the MOSI pin when you're reading data and MISO pin when you're writing data.

I worked on sensor-head (4 channel IR camera, CMOS mux under the IndiumPhosphide laminated sensor) that absolutely would not cooperate with the control-signal-emitting FPGA until I snipped all the digital interface wires (approx. 12 of them) and inserted 1Kohm resistors to greatly slow the edges of the timing signals and thus avoid undershoot (to -5 volts) and overshoot (to +10v) on the 0v/5v interface.

In diagnosing, before inserting the 1Kohm series Rs, I looked using a realtime TEK7904 (500MHz scope, no sampling done) and P6201 (900 MHz probe at 1pF when X10 head was slipped on), I saw these horrid overshoots with 500 picosecond edges running 4" across 1 PCB, another 4" across the 2nd PCB and then running thru a 1" connector and down into the liquid nitrogen dewar.

We thus has 4+4" embedded inside PCB, with effective length of 8" (scaled by sqrt(Er)) thus 4+4 becomes 8+8, with return path making 16+16") plus connector and dewar.

Your SPI is only 3 wires. Explore where, exactly, the reflections/overshoots are best dampened.