1 Features
1• High speed:
– Gain-bandwidth product: 2.7 GHz
– Bandwidth (G = 7 V/V): 765 MHz
– Large-signal bandwidth (2 VPP): 400 MHz
– Slew rate: 1400 V/μs
• Decompensated gain: 7-V/V stable
• Low noise:
– Input voltage noise: 2.2 nV/√Hz
– Input current noise: 3 fA/√Hz (f = 10 kHz)
• Input bias current: 4 pA (typical)
• Low input capacitance:
– Common-mode: 1.9 pF
– Differential mode: 0.5 pF
• Low distortion (G = 7 V/V, RL = 1 kΩ, VO = 2 VPP):
– HD2, HD3 at 1 MHz: –104 dBc, –108 dBc
– HD2, HD3 at 50 MHz: –57 dBc, –72 dBc
• Wide supply range: 6 V to 13 V
• Output swing: 8 VPP (VS = 10 V)
• Supply current: 27.7 mA
• Shutdown supply current: 27 μA
• Performance upgrade to OPA657

2 Applications
• Wideband transimpedance amplifiers (TIAs)
• Wafer scanning equipment
• Optical communication modules
• High-speed data acquisition (DAQ)
• Active probes
• Optical time-domain reflectometry (OTDR)
• Test and measurement front-ends
• Medical and chemical analyzers

3 Description
The OPA818 is a decompensated, voltage-feedback
operational amplifier for high-speed and wide
dynamic range applications. OPA818 has a low-noise
junction gate field-effect transistor (JFET) input stage
that combines high gain-bandwidth with a wide supply
range from 6 V to 13 V. The fast slew rate of
1400 V/μs provides high large-signal bandwidth and
low distortion. This amplifier is manufactured using
Texas Instruments' proprietary, high-speed, silicongermanium
(SiGe) process to achieve significant
performance improvements over other high-speed,
FET-input amplifiers.
The OPA818 is an extremely versatile, wideband TIA
photodiode amplifier for use in optical test and
communication equipment, and many medical,
scientific, and industrial instruments. The OPA818
showcases 2.7 GHz gain-bandwidth, low 2.4 pF total
input capacitance, and 2.2 nV/√Hz input noise. The
OPA818 can achieve over 85-MHz signal bandwidth
in TIA configuration with 20-kΩ TIA gain (RF) and
0.5-pF photodiode capacitance (CD) with wide output
swings. The decompensated, low-noise architecture
with pico amperes of input bias current is also wellsuited
for high-gain test and measurement
applications. Though normally stable in gains ≥ 7 V/V,
the OPA818 can be used in applications with lower
gains by applying noise-gain shaping techniques (see
Non-Inverting Gain of 2 V/V).
The OPA818 is available in an 8-lead WSON
package with an exposed thermal pad for heat
dissipation. This device is specified to operate over
the industrial temperature range of –40°C to +85°C.