Amplifiers – With semiconductor amplifying device – Including differential amplifier
Patent
1989-11-17
1991-07-09
Mottola, Steven
Amplifiers
With semiconductor amplifying device
Including differential amplifier
330279, H03F 345, H03G 330
Patent
active
050309234
ABSTRACT:
A variable gain amplifier includes a first stage amplifying portion and a subsequent stage amplifying portion for amplifying an output from the first stage amplifying portion and outputting an amplified signal to an output terminal. The first stage amplifying portion includes first and second transistors having emitters connected to each other through a resistor based upon which an input dynamic range is determined, and first and second diodes which are connected to collectors of the transistors as loads thereof. A reference current is generated by a reference current generating portion. A control current generating portion generates a control current which is N times the reference current and supplied to the collectors of the first and second transistors. Currents flowing through the first and second diodes is sunk by a current sinking portion. Values of the above reference current and a sunk current by the current sinking portion is controlled by a control portion in accordance with a level of a control signal, whereby a total gain of the variable amplifier can be varied.
REFERENCES:
patent: 4101841 (1978-07-01), Okada et al.
patent: 4134078 (1979-01-01), Arai et al.
"Development of Radio Data System Decoder IC's", Ogawa et al., IEEE Transactions on Consumer Electronics, vol. CE-33, No. 3, Aug., 1987, pp. 383-394.
"Integrated Linear Basic Circuits", van Kessel et al., Philips Technical Review, vol. 32, 1971, No. 1, pp. 1-12 and 32.
Mottola Steven
Sanyo Electric Co,. Ltd.
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