MEMS switched resonators for VCO applications

• US 5,994,982 A
• Filed: 07/18/1997
• Issued: 11/30/1999
• Est. Priority Date: 07/18/1997
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Berenz, John J., Kintis, Mark
• Primary Examiner(s): Ham, Seungsook
• Application Number:
  US08/897,120
• Time in Patent Office: 865 Days
• Field of Search: 333/174, 333/175, 333/205, 333/204, 333/219, 333/235, 333/262, 331/179, 331/117 R, 331/117 D, 331/107 SL, 331/167, 331/99, 331/177 R, 331/177 V, 331/46, 331/34, 334/45, 334/52, 334/55, 334/56, 334/60, 334/64, 334/72, 334/87
• US Class Current: 333/235
• CPC Class Codes: H03B 5/1847 the active element in the amplifier being a semiconductor device

Abstract

A switched resonator formed from a series capacitor and a single microstrip transmission line with a plurality of RF switches to connect it to ground along its length. The microstrip transmission line is grounded at one end and the RF switches are used to tune its length. The other end of the microstrip transmission line is connected to the capacitor to form a resonator. The resonant frequency of the resonator is varied by grounding the center conductor through RF switches connected to ground at different points along its length, which effectively varies the electrical length of the transmission line connected to the capacitor thereby forming a switched resonator. The switched resonator is suitable for use with a single VCO to provide relatively wideband tuning of the significantly reduced size due to the use of a single VCO.

Claims

1. A switchable resonator comprising:

a plurality of resonant circuits for providing respective plurality of resonant frequencies for tuning the resonant frequencies of a voltage controlled oscillator;

a voltage controlled oscillator (VCO), whose output frequency relative to a resonant frequency may be controlled by varying the voltage applied to said VCO. said, VCO selectively connectable to each of said plurality of circuits for selecting the resonant frequency of said VCO; and

a plurality of selectable RF switches for selectively coupling one said plurality of circuits at a time said VCO for electrically tuning the resonant frequency of the switchable resonator.

2. The switchable resonator as recited in claim 1, wherein one or more of said plurality of circuits are formed from a series LC circuit.

3. The switchable resonator as recited in claim 2, wherein said series LC circuit is formed from a capacitor and a predetermined length of microstrip transmission line.

4. The switchable resonator as recited in claim 3 wherein said plurality of resonant frequencies are provided by varying the length of said microstrip transmission line.

5. A frequency synthesizer having a plurality of tunable frequency bands, the frequency synthesizer comprising:

a resonator having a plurality of selectable resonant circuit outputs for providing respective plurality of resonant frequencies;

a voltage controlled oscillator (VCO), whose output frequency relative to a resonant frequency may be controlled by varying of voltage applied to said VCO said VCO selectively coupled to said resonator to provide different frequency bands; and

a plurality of RF switches electrically coupled between said selectable outputs of said resonator and said VCO for electrically tuning the frequency band of the resonator.

6. The frequency synthesizer as recited in claim 5, wherein said resonator is formed from a plurality of series LC circuits.

7. The frequency synthesizer as recited in claim 6, wherein one or more of said series LC circuits is formed from a capacitor and a predetermined length of microstrip transmission line.

8. The frequency synthesizer as recited in claim 7, wherein said plurality of resonant frequencies are provided by varying the length of said microstrip transmission lines.