Transmission-line-based signal distribution and aggregation
A tapped transmission line for distributing an electrical signal, such as an RF signal, to multiple modules, and/or aggregating signals from multiple modules. Embodiments of the invention provide a tapped transmission line based on a transmission-line medium along which tap elements are dispersed, so that the tap elements have a predominantly capacitive loading of the transmission-line medium. Methods for compensating the loss of the transmission-line medium are presented as well. Applications for distribution of transmitted signals, of local oscillator signals, and to aggregation of signals from multiple oscillators are disclosed. The invention is particularly applicable to integrated circuits (IC, ASIC, RFIC), and to multichannel RF systems such as phased array and MIMO systems.
1. A tapped transmission line for distributing a transmitted signal to a plurality of modules, the tapped transmission line comprising:
a first transmission-line medium for carrying a first electrical signal;
a second transmission-line medium for carrying a second electrical signal;
a first plurality of operational tap elements connected to the first transmission-line medium at intervals along a physical length of the first transmission-line medium; and
a second plurality of operational tap elements connected to the second transmission- line medium at intervals along a physical length of the second transmission-line medium;
wherein:
the operational tap elements exhibit predominantly capacitive impedance to the respective transmission-line media;
each module of the plurality of modules is connected to a respective operational tap element of the first plurality of operational tap elements and is connected to a respective operational tap element of the second plurality of operational tap elements; and
outputs of the plurality of modules are not connected to a common transmission-line medium.
2. The tapped transmission line of claim 1 , wherein:
the first electrical signal is an in-phase replica of the transmitted signal; and the second electrical signal is a quadrature replica of the transmitted signal.
3. The tapped transmission line of claim 1 , wherein an operational tap element is selected from a group consisting of: an amplifier, a mixer, a frequency multiplier, and a vector modulator.
4. The tapped transmission line of claim 1 , wherein at least one of the first transmission line medium and the second transmission line medium is a differential transmission-line medium.
5. The tapped transmission line of claim 1 , wherein the transmitted signal is a local oscillator signal.
6. The tapped transmission line of claim 1 , wherein the transmission-line media distribute respective multiple electrical signals to the modules.
7. The tapped transmission line of claim 1 wherein at least one of the first transmission line medium and the second transmission line medium is tapered.
8. The tapped transmission line of claim 1 , wherein the transmitted signal is a radio frequency (RF) signal.