HP 70427A User Manual page 443

Block Diagram
100 MHz Reference Loop (A7A1)
During the positive part of the 20 MHz cycle, current flows from the
impedance transformer, through D1, through the inductor across the bridge
output, through D3, and then through the inductor in the parallel resonator to
ground. The inductor in the parallel resonator has been chosen to be a low
impedance at 20 MHz.
Figure 13-1 20 MHz to 100 MHz Multiplier
During the negative part of the 20 MHz cycle, current flows from ground,
through the inductor in the parallel resonator, through D2, through the
inductor across the bridge output, through D4, and then into the impedance
transformer.
It is important to note that the current in the inductor across the bridge flows
in the same direction in both cases. Since an inductor will not allow its
13-8 HP 70427A/HP 70428A User's Guide