LTC55933
3
ter than 12dB return loss. For LO frequency from
3.4GHz to 3.8GHz, the LO port can be well
matched by using C2 = 0.6pF and L4 = 10nH.
The LTC5593’s LO amplifiers are optimized for the
2.1GHz to 4.2GHz LO frequency range. LO fre-
quencies above and below this frequency range
may be used with degraded performance. The LO
input is always 50
Ω
-matched when VCC is applied
to the chip, even when one or both of the channels
is disabled. The nominal LO input level is 0dBm.
The LO input power range is between -4dBm and
6dBm.
IF OUTPUT
Demonstration Circuit 1710A-D features single-
ended, 50
Ω
-matched IF outputs for 190MHz. The
channel A and the channel B IF outputs are identi-
cal, and the impedance matching is realized with a
bandpass topology using IF.
Demonstration Circuit 1710A-D can be easily re-
configured for other IF frequencies by simply re-
placing inductors L1A, L2A, L1B and L2B. Inductor
values for several common IF frequencies are pre-
sented in Table 3. External load resistor, R2A and
R2B, can be used to improve impedance matching
if desired.
TABLE 3. INDUCTOR VALUES vs. IF FREQUENCIES
IF FREQUENCY (MHz)
L1A, L2A, L1B, L2B (nH)
140
270
190
150
240
100
300
56
380
33
470
22
