The CBDS Driver is a hybrid (current and voltage-mode capable), low power,
high-swing-capable differential driver. Its key characteristic is the Class-B or
push-pull architecture that channels all of the current drawn from the power supply
into the drivern interconnect. While this provides the maximum possible power
efficiency, the presence of independent positive and negative current sources
requires very accurate matching between these current sources. The biasing
architecture of the CBDS Driver in conjunction with appropriate support circuitry
accomplishes this over PVT.
The most advantageous aspect of CBDS is low-headroom, voltage-mode Class-B
application of the CBDS Driver. Here, the bias circuitry, support circuits and
current source devices are designed to exhibit drive path impedances matching
the differential interconnect characteristic impedance. In simple words, at
the extremes of voltage swing in a low-headroom (say 1V) situation, the driver
switches and current sources in combination present 50ohms impedance to both
driven output nodes. This not only provides self-termination for the CBDS
Driver, it provides a true-differential, half-VCC-swing, power-efficient
drive. The CBDS architecture is therefore extremely well-suited to future
revisions of the LVDS Specification as well as for nanoscale, gigahertz
signaling at very low power overhead.
ComLSI’s CBDS technology has been implemented as
transceivers in 180nm logic CMOS, capable of as much as
14ma output current. The full patent may be accessed at
CBDS Driver US Patent 7348810
More information at the
CBDS Patent sale listing
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