Probe Input Architecture - Tektronix TriMode TDP7700 Series Technical Reference

Theory of operation
P77C292MM adapter. Use the P77C292MM, 2.92 mm adapter to connect a
TDP7700 series probe to a DUT with 50 Ω test point connectors. 2.92 mm
connectors are mechanically compatible with SMA connectors.
Figure 3: P77C292MM adapter
The adapter supports testing of serial standards such as HDMI, MIPI M-PHY,
and DisplayPort; cables and retainer are included.
After connecting the adapter to the flex cable, use the retainer to provide a secure
connection to the flex cable to minimize movement or to attach the adapter to the
hand's free tripod.
For stacking more than one adapter, use the linkage adapter accessories to secure
the P77C292MM adapters together.

Probe input architecture

Input architecture
TDP7700 Series probes feature a new probe architecture that addresses the need
for high frequency response with decreased probe loading for high-speed, low
®
power applications such as MIPI and LPDDR. High performance probes with
multi-GHz bandwidth have evolved in recent years, starting from traditional
designs with metal pin tips attached to a probe head amplifier located at the end
of a coaxial cable. As the probe bandwidth extended to 10 GHz and above, probe
designs migrated to connectorized amplifier input structures that supported a
variety of high frequency passive probe tips, including solderable tip designs.
These probe tips typically provide a passive input attenuator network at the probe
tip followed by a long cable attached to the probe amplifier connection socket.
Although these passive tip, probe designs enable good, high frequency
performance, they show higher probe loading in the frequency band below 1 GHz
than earlier traditional designs with an amplifier closer to the probe tip. A probe
with this higher loading characteristic below 1 GHz has problems when taking
measurements of signals such as MIPI that can be switched to an unterminated,
high impedance mode for low power operation. The TDP7700 Series probe
solves this loading problem by introducing an active probe tip design with a tiny
buffer amplifier located near the tip inputs. By locating an amplifier with a high
impedance attenuator network at the probe tip inputs, the probe tip parasitic
capacitance can be kept much lower than passive cable tip designs, thus reducing
probe loading in the low power signaling frequency band used by serial data
standards such as MIPI.
The following figure shows a simplified diagram of the TekFlex active probe tip
architecture.
TDP7700 Series TriMode Probes Technical Reference 5