Amplifiers – With semiconductor amplifying device – Including differential amplifier
Patent
1998-01-23
1999-05-11
Pascal, Robert
Amplifiers
With semiconductor amplifying device
Including differential amplifier
330295, 330 51, 327355, H03F3/45;3/68;1/14
Patent
active
059031913
ABSTRACT:
A digitally controlled variable transconductance amplifier system including first and second input means for receiving first and second input voltages of opposite phase; first and second output means; a voltage to current converter system responsive to the input voltage and including a reference voltage to current converter and a plurality of voltage to current converters each having a different gain relative to the reference voltage to current converter such that the total gain of the voltage to current converters is less than that of the reference converter; each of the converters providing a pair of oppositely phased converter output currents; and a summing system including a reference switching circuit and a plurality of switching circuits, the reference switching circuit and the switching circuits being interconnected with said reference converter and the plurality of voltage to current converters, respectively, the summing system being responsive to a digital control signal for operating each of the switching circuit to selectively deliver one of the converter output currents from the associated converter to one of the first and second output means and the other of the converter output currents to the other of the output means for providing at said output means first and second output currents of opposite or in phase with constant common mode current and having a gain relative to the input voltages which is the sum or difference of the gains of all of the converters and is determined by the digital control signal.
REFERENCES:
patent: 5045804 (1991-09-01), Sugawara et al.
patent: 5821810 (1998-10-01), Swart et al.
Gilbert, Barrie, "A High-Performance Monolithic Multiplier Using Active Feedback", IEEE J. Solid-State Circuits, vol. SC-9, pp. 364-373, Dec. 1974.
"8-Bit, High Speed, Multiplying D/A Converter (Universal Digital Logic Interface", Product Data Sheet DAC08, Analog Devices, Inc.
Analog Devices Inc.
Nguyen Patricia
Pascal Robert
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