| ABSTRACT:
A low component count, high speed sample gate, and digitizer architecture
using the sample gates is based on use of a signal transmission line, a
strobe transmission line and a plurality of sample gates connected to the
sample transmission line at a plurality of positions. The sample gates
include a strobe pickoff structure near the strobe transmission line which
generates a charge displacement current in response to propagation of the
strobe signal on the strobe transmission line sufficient to trigger the
sample gate. The sample gate comprises a two-diode sampling bridge and
is connected to a meandered signal transmission line at one end and to
a charge-holding cap at the other. The common cathodes are reverse biased.
A voltage step is propagated down the strobe transmission line. As the
step propagates past a capacitive pickoff, displacement current i=c(dv/dT),
flows into the cathodes, driving the bridge into conduction and thereby
charging the charge-holding capacitor to a value related to the signal.
A charge amplifier converts the charge on the charge-holding capacitor
to an output voltage. The sampler is mounted on a printed circuit board,
and the sample transmission line and strobe transmission line comprise
coplanar microstrips formed on a surface of the substrate. Also, the strobe
pickoff structure may comprise a planar pad adjacent the strobe transmission
line on the printed circuit board. |