Appeal No. 2005-0827
Application No. 09/903,239
BACKGROUND
The invention is directed to a differential amplifier circuit that reduces the speed-
limiting effects of capacitance by employing passive (rather than active) elements for
biasing. Claim 1 is reproduced below.1
1. A differential amplifier for providing common-mode rejection while
providing differential-mode amplification, comprising:
a. an active differential amplification element electrically coupled to a
first input signal, a second input signal and an output signal, the active differential
amplification element also electrically coupled to a first voltage and a different
second voltage; and
b. a passive bias element electrically coupled to the active differential
amplification element, the passive bias element capable of biasing the active
differential amplification element so that the active differential amplification
element operates in a saturation mode, thereby generating the output signal so
that the output signal corresponds to a voltage difference between the first input
signal and the second input signal.
The examiner relies on the following references:
Sasaki 5,039,873 Aug. 13, 1991
Zhang 6,313,696 B1 Nov. 6, 2001
(filed Dec. 8, 1999)
Claims 1-10 stand rejected under 35 U.S.C. § 103 as being unpatentable over
Zhang and Sasaki.
We refer to the Final Rejection (mailed Mar. 5, 2004) and the Examiner’s Answer
(mailed Oct. 5, 2004) for a statement of the examiner’s position and to the Brief (filed
1 We note that the claim Appendix in appellants’ principal brief contains two versions of claim 3.
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