Tunable bandpass filters often involve a mechanical assembly to shift the passband. But the PTF-2BP300450-10-KT kit from Paratek Microwave provides insight into the capabilities of frequency-selective materials for constructing an electronically tunable bandpass filter that covers 300 to 450 MHz with a 10-percent 3-dB bandwidth. Based on the firm's Passive Tunable Integrated Circuits (PTICs), the demonstrator kit includes an RS-232 interface for connecting the filter to a control personal computer (PC) and SMA connectors for the RF signal connections.
The kit's unique two-pole filter provides 1-MHz tuning resolution. The passband insertion loss is typically only 1 dB while passband return loss is typically 20 dB. The switching speed is 100 microseconds, with stopband rejection of -65 dBc or better. Rejection at the edge of the passband is 22 dB or better. The RF portion of the design measures just 0.8 x 0.4 in.
- Filter Improves Handset Audio Performance
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