45 MHz SAW filter — what the band defines for IF design
The ECS-38SMF45A30 is a two-pole SAW filter centered at 45 MHz with a 30 kHz bandwidth — that bandwidth sets the width of the IF channel it passes, so the filter shape is determined by the 1.1 kΩ impedance and the two-pole roll-off profile rather than a wide guard band.
Passband loss budget
Ripple is held to 1 dB across the passband — a tight flatness figure that matters in communications gear where amplitude variation across the channel distorts the modulation envelope. Insertion loss of 2.5 dB is the SAW tax for the stopband rejection — budget this loss ahead of the following IF amplifier so the noise figure of the chain does not degrade by more than the filter adds.
8-SMD package — board footprint and thermal profile
The 3.80 × 3.80 mm body and 1.20 mm seated height fit the standard half-inchsquare SAW footprint — the no-lead terminations on all eight pads call for a reflow profile that wets the side metallization, not just the base. Operating range is -30°C to 80°C — this is an industrial indoor grade, not automotive or rail, so check the enclosure thermal environment before committing to a board location near heat-producing components.