Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1985-12-20
1987-12-08
Sloyan, T. J.
Communications: electrical
Audible indication
Percussion-type sound producer
323312, 323317, 340347M, H03M 170
Patent
active
047120916
ABSTRACT:
A D/A converter providing a binary weighted series of currents (I.sub.3, I.sub.4, I.sub.5) via first current-source transistors (T.sub.3, T.sub.4, T.sub.5) each in a given ratio to a reference current (I.sub.1) in a reference transistor (T.sub.1). The weighted currents are switched to analog output (15) or to positive supply terminal (20) via first switching devices (3.1, 3.2, 3.3). A control device includes a second current-source transistor (T.sub.8) connected to a reference-current source or to the positive supply terminal via a second switching device (4). The current (I.sub.8) in the transistor T.sub.8 has a given ratio to the reference current (I.sub.1). By connecting the second current-source transistor to the positive supply terminal or to the reference current source, the reference transistor carries the full reference current (I.sub.ref) from the reference current source or only a fraction of the full reference current, respectively. As the weighted currents are in a given ratio to the current (I.sub.1) in the reference transistor, these currents are a similar fraction smaller in the first case than in the second case. By increasing the reference transistor current (I.sub.1) stepwise from a fraction to the full reference current over the range of the digital input code, the converter output current range will also vary stepwise.
REFERENCES:
patent: 3940760 (1976-02-01), Brokaw
The Engineering Staff of Analog Devices, Inc., Analog-Digital Conversion Handbook, 6/1972, pp. I-53 to I-59.
Bierhoff Martinus P. M.
Schoofs Franciscus A. C. M.
Slomp Albert H.
Van Mil Job F. P.
Franzblau Bernard
Mayer Robert T.
Sloyan T. J.
U.S. Philips Corporation
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