TL026C

DIFFERENTIAL HIGH-FREQUENCY AMPLIFIER WITH AGC

SLFS007A – JUNE 1985 – REVISED JULY 1990

7

POST OFFICE BOX 655303

APPLICATION INFORMATION

The circuit values in Figures 6 and 7 will produce the best results in this general application. Because of

rectification and device input constraints, the circuit in Figure 6 will not provide attenuation and has about

32 dB of control range. The circuit shown in Figure 7 will have approximately 25% variation in the peak output

voltage limit due to the variation in gain of the TL592 device to device. In addition, if a lower output voltage is

desired, the output of the TL026C can be used for approximately 40 mV of controlled signal.

considerations for the use of the TL026C

To obtain the most reliable results, RF breadboarding techniques must be used. A groundplane board should

be used and power supplies should be bypassed with 0.1-

µF capacitors. Input leads and output leads should

be as short as possible and separated from each other.

A peak input voltage greater than 200 mV will begin to saturate the input stages of the TL026C and, while the

circuit is in the AGC mode, the output signal may become distorted.

To observe the output signal of TL026C or TL592, low-capacitance FET probes or the output voltage divider

technique shown in Figure 6 should be used.

–

+

+

–

OUT +

OUT –

0.1

µF

0.1

µF

REF

OUT

30 k

Ω

To Scope

Monitor

Vout

200

Ω

1.8 k

Ω

IN –

IN +

50

Ω

AGC

10 k

Ω

10 k

Ω

VAGC

A2

20 k

Ω

50

Ω

VI

+

–

10 k

Ω

A1

12 k

Ω

1N914

D1

0.1

µF

V1

1/2 TL082

1/2 TL082

TL026C

NOTE: VCC + = 6 V and VCC – = – 6 V for TL026C and amplifiers A1 and A2.

Figure 6. Typical Application Circuit With No Attenuation