AD823

REV. 0

–15–

FREQUENCY – Hz

–40

1k

–50

–30

–60

0

–20

10k

100k

1M

10M

100M

–10

Figure 42. Frequency Response of Filter

Single-Supply Half-Wave and Full-Wave Rectifiers

An AD823 configured as a unity gain follower and operated

with a single supply can be used as a simple half-wave rectifier.

The AD823’s inputs maintain picoamp level input currents even

when driven well below the minus supply. The rectifier puts that

behavior to good use, maintaining an input impedance of over

10

11

Ω for input voltages from 1 volt from the positive supply to

20 volts below the negative supply.

The full- and half-wave rectifier shown in Figure 43 operates as

the unity gain follower A1 and the loop of amplifier A2. This

forces the inputs of A2 to be equal, thus no current flows

through R1 or R2, and the circuit output tracks the input. When

noninverting input of amplifier A2 sees the ground level output

of A1, therefore, A2 operates as a unity gain inverter. The out-

put at node C is then a full-wave rectified version of the input.

Node B is a buffered half-wave rectified version of the input.

Input voltage supply to

±18 volts can be rectified, depending on

the voltage supply used.

10

90

100

0%

2V

2V

200

µs

2V

A

B

C

3

2

1

8

4

0.01

µF

V

IN

+V

S

1/2

AD823

HALF-WAVE

RECTIFIED OUTPUT

FULL-WAVE

RECTIFIED OUTPUT

A1

R2

100k

Ω

R1

100k

Ω

6

5

7

1/2

AD823

A2

A

B

C

Figure 43. Single Supply Half- and Full-Wave Rectifier