Signal processing apparatus

A signal processing apparatus, comprising:

• a first signal transforming circuit, comprising:
• four first coupled lines, wherein adjacent ends of two of the first coupled lines are configured to carry a first pair of differential signals respectively;
• and
• two second coupled lines, wherein each second coupled line is magnetically coupled to two of the first coupled lines in parallel and comprises two signal ports, to which the two ends of each of the magnetically-coupled first coupled lines are placed symmetrically, for transferring a second pair of differential signals;
• and
• a second signal transforming circuit, configured to convert between the two second pairs of differential signals at the signal ports and a third pair of differential signals at connecting ports of the second signal transforming circuit.

A signal processing apparatus, comprising:

• a first signal transforming circuit comprising four of first coupled lines and two of second coupled lines magnetically coupled thereto;
• wherein the four first coupled lines and the second coupled lines are arranged to simultaneously form four near-side excitation (NSE) units and four far-side excitation (FSE) units, each of the NSE units comprises first and second near-side ports and a first feed port, a first transfer function of signals on the first near-side port and the first feed port and a second transfer function of signals on the second near-side port and the first feed port are substantially inverse;
• and each of the FSE units comprises first and second far-side ports and a second feed port, a third transfer function of signals on the first far-side port and the second feed port and a fourth transfer function of signals on the second far-side port and the feed port are different by a mismatched term, wherein the mismatched term is substantially zero when a first pair of differential signals are carried by the first and second far-side ports;
• and
• a second signal transforming circuit, configured to convert between two second pairs of differential signals at two ends of the second coupled lines and a third pair of differential signals at connecting ports of the second signal transforming circuit.