I've tried to realise the following circuit:
from this article:
to demod a QPSK signal. I've tried using an AD8347 (Evaluation Board), but
i'm not able to retrieve the "terms at twice the rate of the oscillator".
All I can get from the outputs are the difference between the RF and LO,
both I and Q.
I'm using an (tunable) RF at 1.44GHz and LO at the same frequency. The LO is
generated by ADF411xEB1. Even when I try to tune the RF as close to the LO,
the "terms at twice the rate of the oscillator" never appears.
Is this becaues the range of AD8347 is 0.8-2.7GHz? So the doubler term,
2.88GHz, can never appear?
Has anyone tried any other components to realise this circuit?
Thanx in advance!
- posted 17 years ago