TheoryofOperation
34 P6330 3.5 GHz Differential Probe Instruction Manual
Probe Head and Cable Assembly
Theprobehead assemblycontainsan active amplifier circuit that
buffers and amplifies the input signal. The amplifier receives power
andan offsetlevel from the compensation box assembly via the
cableassembly.
Allsignalamplificationandbufferingisperformedinthe probe head
assembly.No further amplification takes place in thecompensation
box.
Compensation Box
The compensation box contains the following circuits:
HOffsetamplifier
HProbeidentificationEEPROM
HTEKPROBEinterface
HDCCMRRadjustmentcircuitry
HVCC,+7 V linear regulator
OffsetAmplifier
The offset amplifier is used to offset the DC component of the input
signalsothatit stays at the optimal pointofthe linear dynamic range
of the probe.
Theoffsetamplifierreceivesoffsetinformation as a ±1 VDC voltage
fromtheoscilloscope.Theamplifierthen amplifies it to match the
probe characteristics and applies it to the probe hybrid circuit.
Theoffsetamplifierhastwoadjustments:offsetzero andoffsetgain.
Theseadjustmentsrarely needattention;however,detailed
adjustmentinstructionsare in theAdjustments sectiononpage47.
Probe Identification EEPROM
The probe identification EEPROM is used to configure the
oscilloscopeto theprobe.The EEPROMreceivesa clock input from
theoscilloscope,andinformationabout the probe is passed to the
oscilloscope.