My SDR 144 – One band, two designs

For my next 2m band SDR transceiver, I plan to build two different architectures, because testing them is probably the best way to decide which is the most valuable for me.

The first will use a classical topology with an FI on 30MHz. The front-end LNA sends the signal to a mixer, the FI was demodulated by my HF Tyloe mixer, converted by a 24 bits ADC and sent true Ehernet on HDSDR. The mixer chosen for this first version is a ADL5350. Nothing exceptional on the performance side, but I’m sure it will do the the job, and it’s an easy way.

The second one is a zero IF transceiver. Regarding the huge amount of cell phone sold by year, we can say now that it’s a classical topology too 🙂 Usually, the mod & demod chips integrates a phase shifter (90°) and I can reuse my PLL design based on a ADF4157. After this stage, the I/Q signal is sent to a OpAmp (LPF + Gain) and after to the ADC. I selected the duo LTC5584/LTC5598 for this design, but at higher frequencies, SKY73012 & SKY73010 should be  fine too.

I cannot prognostic the winner, but I’m sure it will be very interesting to test and compare 🙂

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