Abstract: A variable attenuator and method of attenuating a signal is presented. The variable attenuator contains an input that receives an input signal to be attenuated. A voltage divider between a resistor and parallel MOSFETs provides the attenuated input signal. The MOSFETs have different sizes and have gates that are connected to a control signal through different resistances such that the larger the MOSFET, the larger the resistance. The control signal is dependent on the output of the attenuator. The arrangement extends the linearity of the attenuation over a wide voltage range of the control signal and decreases the intermodulation distortion of the attenuator.
Type:
Grant
Filed:
September 28, 2005
Date of Patent:
March 17, 2009
Assignee:
Freescale Semicondductor, Inc.
Inventors:
Daniel P. McCarthy, Lawrence E. Connell, Neal W. Hollenbeck