Appeal No. 97-3918
Application 08/447,901
level 0 in Figure 23(A)), and the power for the recording
circuit (not shown) is turned off during each playback
operation (level 1 in Figure 23(A)) -- see Spec. at 3:21 to
4:10. If the rise or decay time of first stage amplifier 22
differs from that of gm amplifier 24, current spikes Ic1 and
Ic2 flow through capacitor 26, as shown in Figure 23(D) (Spec.
at 4:11 to 5:17). This has the effect of delaying the point
in time when the voltage across capacitor 26 is stable enough
to permit commencement of the next type of operation (Spec. at
5:17-20). Appellants' specification notes that while it is
possible to shorten the capacitor charging/discharging time by
increasing the gm value of amplifier 24, that would also have
the undesirable effect of increasing the cut-off frequency of
the low pass filter (defined by the gm value of the gm
amplifier and the capacitance value of capacitor 26 ), thereby 2
disabling effective dc feedback (Spec. at 5:21-25).
Appellants disclose a number of techniques for dealing
with the capacitor charging/discharging problem without
disabling effective dc feedback, only one of which techniques
2Spec. at 3:9-13.
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