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Mode selection in a multimode SAW oscillator using FM chirp mixing signal injection
C B Saw1, P M Smith, P J Edmonson
1Dept. of Electr. and Comput. Eng., McMaster Univ., Hamilton, Ont.
Summary
Researchers achieved mode-selection control in a surface-acoustic-wave (SAW) oscillator using linear FM chirp signal injection. This method enables rapid frequency switching, beneficial for agile radar applications.
Area of Science:
- Electrical Engineering
- Materials Science
- Physics
Background:
- Multimode surface-acoustic-wave (SAW) oscillators can operate at multiple frequencies simultaneously.
- Controlling which mode is active is crucial for applications requiring frequency agility.
Purpose of the Study:
- To demonstrate mode-selection control in a SAW oscillator using a novel injection technique.
- To achieve rapid switching between oscillation modes.
Main Methods:
- A prototype 60-100 MHz SAW oscillator with a single-phase unidirectional transducer (SPUDT) low-loss comb filter was designed.
- Mode selection was accomplished by injecting a signal derived from mixed up- and down-chirp SAW filters.
- The injection signal utilized two 27.5-52.5 MHz chirp filters.
Main Results:
- Successful mode-selection control of the multimode SAW oscillator was achieved.
- The system demonstrated mode switching times of less than 2 microseconds.
- The SAW oscillator exhibited a minimum insertion loss of approximately 3.7 dB.
Conclusions:
- SAW linear FM chirp signal injection is an effective method for controlling multimode SAW oscillators.
- The rapid switching capability makes this device suitable for frequency-agile radars.
- This technology offers a solution for local oscillators requiring moderate frequency hopping.
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