Custom Thin Film Filters and Switched Filter Banks
Networks International Corp. (NIC), a custom manufacturer of RF components, has developed a thin film filter capability for frequency bands from 1 to 20 GHz, with bandwidths from 1 to 60 percent. Using alumina and titanate substrates and thin film lithography, NIC’s filters provide repeatable performance, with low insertion loss and high selectivity. The high dielectic constant substrates enable the filters to be compact and low profile - less than 75 mils high - and compatible with surface-mount assembly.
One example of NIC’s filter capability is a 17.6 GHz thin film filter with a minimum 3 dB bandwidth of 1.4 GHz. The filter has 4.5 dB maximum insertion loss at the center frequency, with 12 dB or better return loss over the passband. Out-of-band rejection is a minimum of 60 dBc from 12 to 15.73 and 19.26 to 27 GHz. The surface-mount package measures 0.45 in. x 0.15 in. x 0.075 in.
Combining thin film and LC filter designs with PIN diode switches, NIC has developed a four-channel switched filter bank to demonstrate the company’s capabilities to develop custom filters. The four passbands cover 4.75 to 7, 9 to 11.8, 12.6 to 14.25 and 14.3 to 15.3 GHz with a maximum passband insertion loss of 5, 5, 7 and 8 dB, respectively. The passband VSWR is 1.5:1 or better and the out-of-band rejection is at least 50 dB. The maximum input power is +23 dBm and switching speed is under 200 ns, controlled with a TTL compatible voltage. The unit is biased with ±5 V and measures 1.8 in. x 1.6 in. x 0.19 in. The surface-mount design meets the vibration, mechanical shock and hermeticity requirements of MIL-STD-202 and MIL-STD-883.
Networks International Corp.
Overland Park, Kan.