In article , John
Miles wrote:

Speaking of quadrature demods, wouldn't best performance be had by
using a 23.3ns ) wideband delay instead of a single or
double-tuned LC. I just found one with 30MHz BW...

Probably not, unless there's something I'm missing. You don't want a
wideband circuit here -- the quadrature detector takes advantage of
phase shift through the passband. Basically it uses a mixer to compare
a signal with a phase-shifted version of itself, with the output being
proportional to the actual phase difference. With a single-tuned
circuit, the 3 dB point corresponds to 45 degrees of phase shift, and
that's where you center the quadrature coil.

Phase shift = delay for a given frequency of course. 90deg at
10.7MHz is 23.3ns. Being wideband means the delay and amplitude change
over a 150kHz BW are MUCH less than with a single LC. Seems to me that
would give the best performance and lowest distortion...

Michael