Highly linear passive FET mixer (27-Jan-2012)
The solution described here addresses the high frequency limitations and high local driving power requirements issues in advanced microwave and mm-wave communication systems where highly linear mixers are required to handle complicated modulation schemes. The solution implements a cascade stacking Field-Effect Transistor configuration.
Avago Technologies
Highly linear passive FET mixer
Abstract
The solution described here addresses the high frequency limitations and high local driving power requirements issues in advanced microwave and mm-wave communication systems where highly linear mixers are required to handle complicated modulation schemes. The solution implements a cascade stacking Field-Effect Transistor configuration.
Description
A. Prior solutions and their disadvantages
In advanced microwave and mm-wave communications systems, highly linear mixers are required to handle complicated modulation schemes such as 32, 64, and higher Quadrature Amplitude Modulation (QAM) signals. To achieve highly linear passive Field-Effect Transistor (FET) mixers, a larger FET size has been used (Figure 1). However, the larger FET has larger parasitic elements on the Cgs, Cgd, and Cds. Those additional parasitic elements deteriorate mixer performance at high frequency operation.
Existing highly linear passive FET mixers are only applicable to the low microwave frequency applications. The other way of realizing the highly-linear mixer is a stacking diode mixer configuration (Figure 2). This is a 2-diode stacking example. A stacking diode mixer does not show frequency band limitation issues due to the additional parasitic element on the semiconductor devices. However, the stacking diode mixer requires higher local (LO) signal power due to the higher LO termination impedance.
Figure 1: Simplified schematic for a conventional passive FET mixer
Figure 2: Simplified schematic for a stacked diode mixer
B. Problems solved by the invention
This invention solves the high frequency limitations and high LO driving power requirements issue.
C. Advantages of the invention over what has been done before
The invented passive FET mixer does not show issues related to frequency band limitation because the proposed configuration does not show additional parasitic elements on the Cgs, Cgd, and Cds. The invented passive FET mixer does not require higher LO driving power.
D. Construction and operation of the invention
The solution is...
Find More Documents Like This
Download this Disclosure
Click here if you want to sign-in now.
