Versatile and compact dc-coupled cml buffer

Abstract

Differential signal output nodes of a novel CML buffer are DC-coupled by contiguous conductors to the differential signal input nodes of a load (for example, a CML logic element). The CML buffer includes a pulldown load latch that increases buffer transconductance and that provides a DC bias voltage across the conductors and onto the input nodes of the load, thereby obviating the need for the load to have DC biasing circuitry. Capacitors of a conventional AC coupling between buffer and load are not needed, thereby reducing the amount of die area needed to realize the circuit and thereby reducing the capacitance of the buffer-to-load connections. Switching power consumption is low due to the low capacitance buffer-to-load connections. Differential signals can be communicated from buffer to load over a wide frequency range of from less than five kilohertz to more than one gigahertz with less than fifty percent signal attenuation.