Amplifiers – With semiconductor amplifying device – Including differential amplifier
Patent
1997-03-18
1999-08-10
Mottola, Steven
Amplifiers
With semiconductor amplifying device
Including differential amplifier
330261, H03F 345
Patent
active
059364653
ABSTRACT:
A bipolar OTA having a wide input voltage range is provided without increasing the circuit scale and current consumption. This OTA includes first to n-th differential pairs of first to 2n-th bipolar transistors whose emitters are coupled together, where n.gtoreq.2; and a common current source/sink connected to the emitters of the first to 2n-th transistors. The first to 2n-th transistors are driven by a common tail current produced by the common current source/sink. The transistors of each of the second to n-th differential pairs have a same emitter area K.sub.1 to K.sub.n-1 times as large as that of the first and second transistors, where K.sub.1 to K.sub.n-1 >1. A first input voltage as an input signal to be amplified is differentially applied across bases of the first and second transistors of the first differential pair. A second to n-th input voltages are differentially applied across corresponding bases of the third to 2n-th transistors, respectively. Each of the second to n-th input voltages is produced by attenuating the first input voltage. First to (n-1)-th pairs of dc offset or tuning voltages are applied to the bases of the third to 2n-th transistors, respectively. An amplified output signal is differentially derived from collectors of the first and second transistors.
REFERENCES:
patent: 4723110 (1988-02-01), Voorman
patent: 4951003 (1990-08-01), De Jager et al.
patent: 5382917 (1995-01-01), Miyake et al.
patent: 5389895 (1995-02-01), Moore et al.
Schmoock (1975) "An Input Stage Transconductance Reduction Technique for High-Slew Rate Operational Amplifiers", IEEE Journal of Solid-State Circuits SC-10(6): 407-411.
Tanimoto et al. (1991) "Realization of a 1-V Active Filter Using a Linearization Technique Employing Plurality of Emitter-Coupled Pairs", IEEE Journal of Solid-State Circuits 26(7): 937-945.
Mottola Steven
NEC Corporation
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