Transcript ECE 662 - George Mason University

ECE 662
Microwave Electronics
Transferred Electron Devices
February 10, 2005
Two-Terminal Negative
Resistance Devices
Transferred Electron Device
Operation (TED)
Review of Carrier Transport
Review of Carrier Transport
Drift Velocity vs. Electric Field
Silicon at Room Temperature
Ref. Sze
Drift Velocity vs Electric Field
Ref Sze
High Field Transport in n-type GaAs
Negative Differential Resistance
in n-type GaAs
Measured velocity-field characteristics
Ref Sze
Review of Carrier Transport
Transferred Electron Device Operation (TED)
Transferred Electron Device Operation (TED)
Electron accumulation in the
Presence of Negative Differential
Resistivity (NDR)
Ref: Liao
Gunn Diode
Eventually, the process evens out and velocities are equal.
Space charge than drifts to anode end and the process repeats.
v d
Drift time L/vd   R 
or Ln0 
 1012 cm 2
e  _ n0
e _

where  _ is thenegativedifferential mobility.
T heseare T ransit time modes.- one domain at a timemust clear out.
f  1/T  v d /L  1/ t ; vd  107 cm / sec
f  not affectedby theexternalcircuit.
Dipole Layer in
Negative Differential
Resistivity (NDR)
Ref: Liao
(a) To (d)
Electric field vs.
distance during
one ac cycle at
Four intervals, a
to d.
e) Voltage and
Current wave
Forms of a
Transit time
Domain mode.
Ref. Sze
Gunn Domain
Modes
Ref Liao
Numerical
simulation
of the timedependant
behavior of
cathodenucleated
TED for the
transit-time
domain mode.
Each successive
time is 24ps.
ref. Sze
Gunn Domain Modes
Ref Liao
Numerical
simulation
of the timedependant
behavior of
cathodenucleated
TED for the
quenched
domain mode.
Each successive
time is 24ps.
ref. Sze
Biasdependent RF
characteristics
of a D-band
InP TED
Mechanical
tuning
characteristic
for the
D-band InP
TED close
to maximum
bias
Typical Structures and Doping
Profiles for TED Devices
Ref. Sze
Solid-State
Device
Power
Output vs
Frequency
ref: Sze
and
modified
by Tian
State-of-the
Art RF
Power Levels
for TED
under CW
operation
ref. Sze
Summary of Transferred Electron
Devices - 1 Ref: Golio (2003)
• Widely used in oscillators from the
microwave through high mm-wave
frequency bands.
• Good RF output power capability (mW to
W level)
• Moderate efficiency (20%)
• Excellent noise and bandwidth capability
Summary of Transferred Electron
Devices - 2 Ref: Golio (2003)
• Fabricated at low cost
• Excellent price-to-performance ratio, for
example, most common oscillator device
used in police automotive radars
• Many commercially available solid-state
sources for 60 to 100 GHz (for example,
automotive collision-avoidance radars)
often use InP TEDs.