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US5130669: Apparatus for driving a mechanical resonator from a high impedance source

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Filing Information

Inventor(s) Leroy S. Wignot · Gene K. Sendelweck · Daniel M. Hutchinson ·
Assignee(s) Thomson Consumer Electronics, Inc. ·
Attorney/Agent(s) Joseph S. Tripoli ·
Primary Examiner James B. Mullins ·
Application Number US7506769
Filing date 04/12/1990
Issue date 07/14/1992
Predicted expiration date 04/12/2010
U.S. Classifications 330/306  · 330/148  ·
International Classifications H03F 3191  ·
Kind CodeA
International Classifications 330148;174;306 ·
6 Claims, No Drawings


Abstract

The present invention concerns a high impedance signal source driving a relatively low input impedance mechanical resonating device such as a ceramic filter having an input impedance which varies with frequency. The high impedance source is further loaded by a resonant circuit tuned to the center frequency of the mechanical resonating device. The skirts of the resonant tuned circuit decrease in impedance on both sides of the center frequency of interest substantially compensating for the change of circuit gain with frequency due to the change of input impedance with frequency of the ceramic filter.

Independent Claims | See all claims (6)

  1. 1. An amplifier circuit comprising:amplification means having a relatively high impedance signal output means for providing a signal over a bandwidth of frequencies,a first load means coupled in parallel with the high impedance signal output means, said first load means having a first impedance versus frequency characteristic with an impedance over a portion of the bandwidth which is relatively lower than the high impedance signal output means, anda second load means coupled in parallel with the high impedance signal output means, said second load means having a second impedance versus frequency characteristic which is complementary to the first impedance versus frequency characteristic with an impedance over a portion of the bandwidth which is relatively lower than the high impedance signal output means such that the amplitude versus frequency characteristic of a signal at the high impedance signal output means over the bandwidth is in part determined by the loading of the high impedance signal ouput means by the first load means and in part determined by the loading of the high impedance signal output means by the second load means.
  2. 4. An amplifier circuit comprising:amplification means having a relatively high impedance output means for providing a signal over a bandwidth of frequencies, said amplification means being a transistor having an emitter electrode providing a low impedance first signal output thereat, and a collector electrode providing a high impedance second signal output thereat,a first load means coupled in parallel with the high impedance output means, said first load means having a first impedance versus frequency characteristic with an impedance over a portion of the bandwidth which is relatively lower than the high impedance output means, anda second load means coupled in parallel with the high impedance signal output means, said second load means having a second impedance versus frequency characteristic which is complementary to the first input impedance versus frequency characteristic with an impedance over a portion of the bandwidth which is relatively lower than the high impedance signal output means such that the amplitude versus frequency characteristic of a signal at the high impedance signal output means over the bandwidth is in part determined by the loading of the high impedance signal output means by first load means and in part determined by the loading of the high impedance signal output means by the second load means.
  3. 6.6. An amplifier circuit comprising:amplification means having a relatively high impedance output means for providing a signal over a bandwidth of frequencies, said amplification means being a transistor having a collector electrode comprising the high impedance output means and providing a sound signal output thereat,a first load means coupled in parallel with the high impedance output means, said first load means having a first impedance versus frequency characteristic and an impedance over a portion of the bandwidth which is relatively lower than the high impedance output means, anda second load means coupled in parallel with the high impedance signal output means, said second load means having a second impedance versus frequency characteristic which is complementary to the first input impedance versus frequency characteristic and an impedance over a portion of the bandwidth which is relatively lower than the high impedance signal output means such that the amplitude versus frequency characteristic of a signal at the high impedance signal output means over the bandwidth is in part determined by the loading of the high impedance signal output means by the first load means and in part determined by the loading of the high impedance signal output means by the second load means.

References Cited

U.S. Patent Documents

Document NumberAssigneesInventorsIssue/Pub Date
US2308258 RCA CORP Armstrong et al. Jan 1943
US3054969 GEN DYNAMICS CORP Harrison Sep 1962
US3091659 MOTOROLA INC Massman May 1963
US4271433 RCA Corporation Therault Jun 1981
US4316220 RCA Corporation Muterspaugh et al. Feb 1982
US4376953 NAIMPALLY SAIPRASAD V Naimpally Mar 1983
US4410864 RCA Corporation Muterspaugh et al. Oct 1983
US4818959 TDK Corporation Katoh Apr 1989

Foreign Patent Documents

Document NumberAssigneesInventorsIssue/Pub Date
JP9316Jan 1977

Other Publications

Sauerland et al, "Ceramic IF Filters for Consumer Products", IEEE Spectrum, Nov. 1968, pp. 112-126.

Referenced By

Document NumberAssigneeInventorsIssue/Pub Date
AU650811 MOTOROLA INC TATTERSAL DEREK L JR et al. Jun 1994
US6052033 Logitech, Inc. Gerhard Schneider Apr 2000