Semiconductor integrated circuit

Details Semiconductor integrated circuit Semiconductor integrated circuit

2006-03-24

2009-02-17

Vuong, Quochien B (Department: 2618)

Telecommunications

Receiver or analog modulated signal frequency converter

Frequency modifying or conversion

C455S252100, C455S323000

Reexamination Certificate

active

07493098

ABSTRACT:
In a communication semiconductor integrated circuit, a capacitance included in a filter on the output side of a mixer circuit is reduced without requiring the cutoff frequency of the filter to be changed. A Gilbert cell circuit is used as a mixer circuit which combines, for downconversion, a reception signal and a local oscillator signal. A low-pass filter for removing unwanted waves from output is composed of load resistors of upper stage differential transistors and a capacitive element provided between differential output terminals. The resistances of the load resistors are increased, and a current circuit for applying a current to emitters or collectors of the upper stage differential transistors is provided, so that a current to make up for a decrease in current amount attributable to the increase in load resistance can be applied from the current circuit to lower stage differential transistors.

REFERENCES:
patent: 3886458 (1975-05-01), Matsumoto et al.
patent: 6725030 (2004-04-01), Vathulya
patent: 6901249 (2005-05-01), Kobayashi
patent: 6947720 (2005-09-01), Razavi et al.
patent: 2004-104040 (2004-04-01), None

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