Abstract: A digital calibration circuit is used to provide joint-elimination of transmitter and receiver I/Q imbalances. Digital I and Q quadrature signals are received and converted to analog I and Q quadrature signals on I and Q for transmission on output channels. An output mixer is used to convert the quadrature signals to an unbalanced RF output. An unbalanced RF signal is received selectively either externally or from the RF output using a source follower, and the received signal is mixed to provide analog I and Q quadrature signals, using a local oscillator (LO). The LO adds an additional 90 ° phase shift between I and Q quadrature channels of the unbalanced RF input. Parameter estimating the transmitted digital I and Q quadrature signals and providing estimations of I and Q quadrature imbalance conditions.

Abstract: A digital calibration circuit is used to provide joint-elimination of transmitter and receiver I/Q imbalances. Digital I and Q quadrature signals are received and converted to analog I and Q quadrature signals on I and Q for transmission on output channels. An output mixer is used to convert the quadrature signals to an unbalanced RF output. An unbalanced RF signal is received selectively either externally or from the RF output using a source follower, and the received signal is mixed to provide analog I and Q quadrature signals, using a local oscillator (LO). The LO adds an additional 90° phase shift between I and Q quadrature channels of the unbalanced RF input. Parameter estimating the transmitted digital I and Q quadrature signals and providing estimations of I and Q quadrature imbalance conditions.

Abstract: The present invention discloses a panel holder, which comprises a chassis. The chassis further comprises a frame. At least one first connection portion and at least one second connection portion are formed on two pairs of opposite laterals of the frame. First fixing members are installed in the laterals of the frame via the first connection portions, and a first type panel can be fixed to the chassis via the first fixing members. Alternatively, second fixing members are installed in the laterals of the frame via the second connection portions, and then, a second type panel can be fixed to the second fixing members. Therefore, in the present invention, an identical chassis can accommodate different types of panels.