In one aspect, the invention provides an electronic system comprising: a Doubly Balanced Mixer (DBM) circuit: a Local Oscillator (LO) port to the DBM adapted to accept a balanced input: a nonreactive impedance matching network the output of which is operably connected to the balanced input port; and a LO circuit operably attached to the input of said impedance matching network by an AC coupling and impedance matching circuit: wherein the selection of pullup, pulldown, or voltage divider devices at the output of the LO are optimized to minimize thermal noise.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts an exemplary embodiment of an Active Ruler? showing educational information content including reference material, communications technique pedagogical data, schematic diagram, component identification, standard and scaled-function ruler markings, and a region where a builder will attach SMD components.
FIG. 2A depicts an exemplary SMD Morse code key depicted over a coin cell battery as its electrical contact ready for keying, with a tail tab descending into the PCB.
FIG. 2B depicts a physical code key samples clearly showing tab tail used for structurally sound and stable assembly by builder.
FIG. 2C depicts surface mount code key materials before shaping into a 3D code key, marked to indicate bends and tail tab, depicting the disclosed method of fabrication.
FIGS. 3A and 3B depict a conventional DBM circuit with single-sided (unbalanced) feed, in two common schematic depictions, respectively.
