Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1983-12-05
1984-08-28
Sloyan, T. J.
Communications: electrical
Audible indication
Percussion-type sound producer
340347M, 340347C, 340347AD, 370 7, H03K 1317
Patent
active
044686536
ABSTRACT:
An integratable PCM decoder requiring a total capacitance of only 32 times the normalized capacitance Co of the smallest capacitor thereof. The decoder comprises a source of positive and negative reference voltages, a differential input operational amplifier having its non-inverting input connected to ground, a storage capacitor CO=16Co connected as a feedback capacitor between the inverting input and the output terminals of the amplifier so that they operate as a voltage source, binary weighted capacitors C1=Co, C2=Co, C3=4Co and C4=8Co, and a second unit weighted capacitor C5=Co. In a mu-law decoder, switch means alternately connect one and other sides of ones of C1-C5 (1) between ground and either a.+-.reference voltage or ground, in accordance with the characterizations in a PCM coded digital input word, and (2) across the storage capacitor CO for redistributing charge on the capacitors for each segment of a designated polarity. In an A-law decoder, the switch means alternately connects one and other sides of ones of C1-C5 (1) between ground and either a.+-.reference voltage or ground, in accordance with the characterizations in a PCM coded digital input word, for sampling charge, and (2) between one side of CO and ground for transferring charge to CO for the first segment associated with a PCM word, and across the storage capacitor CO for redistributing charge on the capacitors for other segments of a designated polarity. The resultant analog signal established on CO in the eighth segment is sampled prior to resetting the charge voltage on CO to substantially zero volts and receipt of the next PCM input word. Connections of plates of integrated capacitors and electrodes of switching transistors to ground and terminals of voltages sources renders the decoder substantially insensitive to stray and parasitic capacitance effects associated with the integrated capacitors and switches.
REFERENCES:
patent: 3541446 (1968-09-01), Prozeller
Tsividis et al., A Segmented U-255 Law PCM Voice Encoder . . . , IEEE Journal of Solid-State Circuits, vol. SC-11, No. 6, 12/1976, pp. 740-747.
Caves et al., A PCM Voice Codec with On-Chip Filters, IEEE Journal of Solid-State Circuits, vol. SC-14, No. 1, 2/1979, pp. 65-73.
Haque et al., A Two Chip PCM Voice Codec with Filters, IEEE Journal of Solid-State Circuits, vol. SC-14, No. 6, 12/1979, pp. 961-969.
Cannon Russell A.
GTE Network Systems Incorporated
Sloyan T. J.
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