Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / Q‐enhanced filtering technologies have been heavily researched, but have not yet been adopted
into commercial designs due to tuning complexity, and performance issues such as noise figure and
dynamic range. A multi‐pole Q‐enhanced band‐pass filter operating at 450 MHz with tunable bandwidth
is developed in this thesis. A noise figure of 14 dB and dynamic range of 140 dB/Hz have been
measured, making the filter suitable for operating in the IF subsystem of a radio receiver.
The design utilizes off‐chip resonators, created using surface mount components or embedded
passives in LTCC processes, to have a reasonably high base‐Q. The equivalent parallel loss resistance of
the finite‐Q inductor and connected circuitry at resonance is partially offset by negative resistances,
implemented with tunable on‐chip transconductors, as required to reach the needed Q for the targeted
bandwidth. Each pole of the filter has binary weighted negative resistance cells for Q‐enhancement and
binary weighted capacitances for frequency tuning. Binary weighted capacitive coupling cells allow the
filter to achieve the level of coupling appropriate to the targeted bandwidth.
To maintain the filter bandwidth, center frequency, and gain over environmental changes a realtime
tuning algorithm is needed. A low complexity tuning algorithm has been implemented and found
to accurately maintain the bandwidth, center frequency, and gain when operating at bandwidths of 10
or 20 MHz. Flatness of the pass‐band is also maintained, to within 0.5 dB across a temperature range of
25‐55 degrees C. In addition to the implementation of the tuning algorithm, the thesis provides a
solution for pass‐band asymmetries spawned from the use of finite‐Q resonators and associated control
circuitry.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/4997 |
| Date | January 1900 |
| Creators | Schonberger, Joel Raymond |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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