Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Patent
1995-01-10
1997-01-14
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
327563, 330253, 330257, 330296, H03B 100, H03K 500
Patent
active
055943837
ABSTRACT:
A Gm-controllable amplifier is used in an OTA-C filter. Specifically, the amplifier is one in which a constant voltage from a bias circuit is applied to the gates of load MOSFETs connected to the drains of input differential MOSFETs of a differential amplifier to allow the load MOSFETs to operate as constant current sources and the inverted output terminals of the circuit are connected to the input terminals. The load MOSFETs of the input differential MOSFETs are made to operate as the constant current sources, so that the drain voltages of the input differential MOSFETs become independent of the threshold voltage of the load MOSFETs. Even if the supply voltage is set to as low as about 1.5 V, the input differential MOSFETs can be prevented from being unsaturated when the input signals rise. Since the inverted output terminals are coupled to the input terminals, the currents outputted from the inverted output terminals in the opposite direction of the current coming from the non-inverted output terminals can be absorbed from the non-inverting input terminals, so that the balance of the circuit can be easily maintained.
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Callahan Timothy P.
Hitachi , Ltd.
Nu Ton My-Trang
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