6
LT1222
1222fc
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
Large Signal, A
V
= 10Small Signal, A
V
= 10
R
F
= 909Ω
R
G
= 100Ω
LT1222 • TPC19 LT1222 • TPC20
Large Signal, A
V
= 10,
C
L
= 10,000pF
LT1222 • TPC21
Small Signal, A
V
= –10
LT1222 • TPC22 LT1222 • TPC23 LT1222 • TPC24
Large Signal, A
V
= –10
Small Signal, A
V
= –10,
C
L
= 1,000pF
R
F
= 909Ω
R
G
= 100Ω
R
F
= 1k
R
G
= 100Ω (75)
R
F
= 1k
R
G
= 100Ω (75)
V
S
= ±15V
V
IN
= 20mV
f = 5MHz
V
S
= ±15V
V
IN
= 20mV
f = 5MHz V
S
= ±15V
V
IN
= 2V
f = 2MHz
V
S
= ±15V
V
IN
= 2V
f = 2MHz
APPLICATIONS INFORMATION
WUU
U
The LT1222 is stable in noise gains of 10 or greater and
may be inserted directly into HA2520/2/5, HA2541/2/4,
AD817, AD847, EL2020, EL2044 and LM6361 applica-
tions, provided that the nulling circuitry is removed and
the amplifier configuration has a high enough noise gain.
The suggested nulling circuit for the LT1222 is shown in
the following figure.
Layout and Passive Components
The LT1222 amplifier is easy to apply and tolerant of less
than ideal layouts. For maximum performance (for ex-
ample, fast settling time) use a ground plane, short lead
lengths and RF-quality bypass capacitors (0.01μF to 0.1μF).
For high drive current applications use low ESR bypass
capacitors (1μF to 10μF tantalum). Sockets should be
avoided when maximum frequency performance is re-
quired. For more details see Design Note 50. Feedback
resistors greater than 5k are not recommended because a
pole is formed with the input capacitance which can cause
peaking or oscillations. Stray capacitance on Pin 5 should
be minimized. Bias current cancellation circuitry is em-
ployed on the inputs of the LT1222 so the input bias current
and input offset current have identical specifications. For
this reason, matching the impedance on the inputs to
reduce bias current errors is not necessary.
Offset Nulling
LT1222 • AI01
V
+
V
–
0.1μF
0.1μF
5k
3
2
4
7
6
8
1
LT1222
+
–
R
F
= 909Ω
R
G
= 100Ω
V
S
= ±15V
V
IN
= 2V
f = 20kHz
R
F
= 1k
R
G
= 100Ω (75)
V
S
= ±15V
V
IN
= 15mV
f = 500kHz
