Low-loss tunable ferro-electric device and method of characterization

• US 6,690,176 B2
• Filed: 08/08/2001
• Issued: 02/10/2004
• Est. Priority Date: 04/11/2001
• Status: Expired due to Fees

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Wireless Corporation (Kyocera Corporation)
• Inventors: Toncich, Stanley S.
• Primary Examiner(s): Hirshfeld, Andrew H.
• Assistant Examiner(s): Hamdan, Wasseem H.
• Application Number:
  US09/927,732
• Publication Number:
  US 20020149448A1
• Time in Patent Office: 916 Days
• Field of Search: 324/629, 324/630, 324/631, 324/632, 324/633, 324/638, 324/639, 324/649, 257/295, 257/751, 257/297, 257/298, 257/312, 343/767, 343/787, 333/161, 333/1.1
• US Class Current: 324/629
• CPC Class Codes: G01R 27/2694 Measuring dielectric loss, e.g. loss angle, loss factor or power factor
• CPC Class Codes: H01G 7/06 having a dielectric selected for the variation of its permittivity with applied voltage, i.e. ferroelectric capacitors electrets H01G7/02
• CPC Class Codes: H01L 27/0808 Varactor diodes
• CPC Class Codes: H01P 1/203 Strip line filters
• CPC Class Codes: H01P 1/20336 Comb or interdigital filters
• CPC Class Codes: H01P 1/20363 Linear resonators
• CPC Class Codes: H01P 1/20381 Special shape resonators
• CPC Class Codes: H01P 1/2039 Galvanic coupling between Input/Output
• CPC Class Codes: H01P 1/2056 Comb filters or interdigital filters with metallised resonator holes in a dielectric block
• CPC Class Codes: H01P 1/213 combining or separating two or more different frequencies H01P1/215 takes precedence
• CPC Class Codes: H01P 5/04 with variable factor of coupling
• CPC Class Codes: H03B 5/04 Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
• CPC Class Codes: H03B 5/124 the means comprising a voltage dependent capacitance
• CPC Class Codes: H03B 5/1262 the means comprising switched elements
• CPC Class Codes: H03B 5/1293 having means for achieving a desired tuning characteristic, e.g. linearising the frequency characteristic across the tuning voltage range
• CPC Class Codes: H03B 5/1841 the frequency-determining element being a strip line resonator H03B5/1805, H03B5/1817, H03B5/1864 and H03B5/1882 take precedence
• CPC Class Codes: H03B 5/362 the amplifier being a single transistor H03B5/364 - H03B5/368 take precedence
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 : Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 3/191 : Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03H 7/0123 : comprising distributed impedance elements together with lumped impedance elements
• CPC Class Codes: H03H 7/12 : Bandpass or bandstop filters with adjustable bandwidth and fixed centre frequency H03H7/09 takes precedence; automatic control of bandwidth in amplifiers H03G5/16
• CPC Class Codes: H03H 7/20 : Two-port phase shifters providing an adjustable phase shift
• CPC Class Codes: H03J 5/246 : using electronic means H03J5/244 takes precedence
• CPC Class Codes: H03L 1/022 : by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature H03L1/021 takes precedence
• CPC Class Codes: H03L 7/18 : using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• CPC Class Codes: H04B 1/0053 : with common antenna for more than one band
• CPC Class Codes: H04B 1/0458 : Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H
• CPC Class Codes: H04B 1/30 : for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 1/40 : Circuits

Abstract

A tunable ferroelectric component and a narrowband resonant circuit for measuring the loss of the ferroelectric component. The ferroelectric component may be a capacitor integrated in the resonant circuit. The testing method eliminates other sources of loss to isolate the loss due to the ferroelectric material and to demonstrate that this loss is low.

Claims

1. A method for determining an insertion loss associated with a ferroelectric circuit component comprising:

fabricating a circuit comprising the ferroelectric component;

measuring an insertion loss of the circuit;

determining a portion of the insertion loss of the circuit that is due to loss sources other than the ferroelectric component;

subtracting the portion due to other loss sources from the measured insertion loss of the circuit;

determining the loss associated with the ferroelectric component; and

recognizing, based on the determined loss associated with the ferroelectric component, that the Q of the component is higher than 100.

2. A method as claimed in claim 1, wherein the ferroelectric component is a gap capacitor.

3. A method as claimed in claim 2, wherein the circuit comprises an integrated structure including a resonator integrated with the gap capacitor.

4. A method as claimed in claim 3, the integrated structure comprises conductive strips deposited on a low loss substrate separated by a gap, and a thin film of ferroelectric material underneath the gap.

5. A method as claimed in claim 1, wherein the ferroelectric component is selected from a group comprising an interdigital capacitor;

a gap capacitor and an overlay capacitor.

6. A method as claimed in claim 1, wherein the circuit is a narrowband resonant circuit.

7. A method as claimed in claim 1, wherein the insertion loss due to the ferroelectric component is measured using a network analyzer.

8. A method as claimed in claim 1, wherein the components of the insertion loss that are due to other loss sources are determined using a circuit simulation tool.

9. A method as claimed in claim 1, wherein the components of the insertion loss that are due to other loss sources are determined using a electromagnetic field simulation tool.

10. A method as claimed in claim 1, wherein the ferroelectric component has a Q greater than 100.

11. A method as claimed in claim 1, wherein the ferroelectric component has a Q greater than 200.

12. The method of claim 1, wherein the circuit comprises a narrowband resonant circuit.

13. The method of claim 1, wherein the portion comprises a metal loss.

14. The method of claim 1, wherein the portion comprises an attachment loss.

15. A The method of claim 1, wherein the portion comprises a geometry loss.

16. The method of claim 1, further comprising measuring the insertion loss with a network analyzer.

17. A method for determining an insertion loss associated with a ferroelectric capacitor comprising:

fabricating a narrowband resonant circuit that integrates the ferroelectric capacitor;

measuring a center frequency and an insertion loss of the circuit;

determining a portion of the insertion loss of the circuit that is due to a part of the resonant circuit other than the ferroelectric capacitor;

removing the portion from the measured insertion loss;

determining the loss due to the ferroelectric capacitor; and

recognizing, based on the determined loss associated with the ferroelectric component, the Q of the component is higher than 100.

18. A method as claimed in claim 17, wherein the narrowband resonant circuit comprises a microstrip resonator having a gap to define the capacitor.

19. The method of claim 17, wherein the portion comprises a metal loss.

20. The method of claim 17, wherein the portion comprises an attachment loss.

21. The method of claim 17, wherein the portion comprises a geometry loss.

22. The method of claim 17, wherein the circuit comprises a narrowband resonant circuit.

23. The method of claim 17, further comprising measuring the insertion loss with a network analyzer.

24. A method of testing a tunable ferroelectric component configured to operate in a tunable frequency range comprising:

designing a resonant circuit configured to resonate in the tunable frequency range;

coupling the resonant circuit to the tunable ferroelectric component;

measuring the loss in the tunable ferroelectric component using the tunable circuit; and

determining non-ferroelectric sources of loss associated with the ferroelectric component to demonstrate that the ferroelectric loss associated with the component is acceptably low.