8

LT1466L/LT1467L

Figure 1. Simplified Schematic

Q3

D1

Q4

Q6

1466L/67L F01

Q1

Q8

Q12

Q13

Q2

Q5

–IN

+IN

BUFFER AND

OUTPUT BIAS

C1

C2

OUT

Q7

Q10

Q11

Q9

Rail-to-Rail Operation

The LT1466L/LT1467L differ from conventional op amps

in the design of both the input and output stages. Figure 1

shows a simplified schematic. The input stage consists of

two differential amplifiers, a PNP stage Q1-Q2 and an NPN

stage Q3-Q4, that are active over different portions of the

input common mode range. Each input stage is trimmed

for offset voltage. A complementary output configuration

(Q12-Q13) is employed to create an output stage with rail-

to-rail swing. The devices are fabricated on Linear

Technology’s proprietary complementary bipolar process,

which ensures very similar DC and AC characteristics for

the output devices Q12 and Q13.

First, looking at the input stage, Q5 switches the current

negative supply, Q5 is reverse biased, so the current from

supply, the PNPs Q1-Q2 are biased off. The current from

Large-Signal Response

1466L/67L G23

FREQUENCY (Hz)

100

130

120

110

100

90

80

70

60

50

40

30

1k

10k

100k

1466L/67L G24

Channel Separation vs Frequency

1466L/67L G22

Small-Signal Response