Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Reexamination Certificate
2007-08-28
2007-08-28
Urban, Edward F. (Department: 2618)
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
C455S313000, C455S296000, C327S101000, C327S117000
Reexamination Certificate
active
10531231
ABSTRACT:
The present invention relates generally to communications, and more specifically to a method and apparatus for minimizing DC offset and second-order modulation products (IM2 noise) while demodulating RF signals. The principle of the invention can be applied to differential, down-conversion circuits (50) consisting of two differential mixers (54, 56) in series, a follows: a pair of current sources Ia and Ib are used to provide current to positive and negative channels of the first differential mixer (54). Providing current to the amplifying transistors of the first mixer (54) reduces the current drawn through the active mixer switches, reducing the noise generated. The current sources1aand1bare trimmed in a complementary manner where1a=I+Delta1, and1b=Delta1. The value of Δ1can be determined in a number of manners; for example, it could be established by testing after the circuit has been fabricated, and the value stored on-chip, for future use.
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Borden Ladner Gervais LLP
Chow Charles
Hung Shin
Sirific Wireless Corporation
Urban Edward F.
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