Heat problem in AD811ANZ

Question

Hello all, 
 I am using AD811 in my amplifier circuit.In this circuit ,I am giving 1V sine ,triangular and square wave signal at 10Hz to2MHz to the input of amplifier.If I use this IC ,over a long period of time ,it produce the heat on the surface of the IC.Eventhough I got a good output response form this IC .If I use this IC continuously the heat problem completely affect the IC of functionality and it will lead to IC dead. 
 Hereby, I attached the my amplifer circuit for your reference. 
 Please suggest the good solution for this problem. 
 Thanks with Regards, 
 Newengg

FormerMember · Accepted Answer

Newengg, 
 Your feedback resistor is way too high. I would suspect it is oscillating. Put a scope on the output. 
 Also, you need a cap, say 10uF, on the wiper of R1. If there is no noise on the -15V, but 2mV on the 
 +15V, and the pot is centered, you will have 1mV noise on the wiper which goes directly into your 
 signal path. The LM324 will have drift with temperature, so you probably can eliminate the op amp 
 entirely. If you don't need a large adjustment range, make R6 ten times larger. 
 Harry

FormerMember · Answer

Newengg, 
 Yes, I think you can eliminate the LM324 buffer. It only adds more error/noise. 
 As I mentioned earlier, noise on the +15V or on the -15V will affect the voltage on 
 the wiper of the pot, so it will get into your signal path. That is why you need a 
 cap on the wiper to ground. 
 Harry

FormerMember · Answer

Newengg, 
 With 30V across the part, and 16 mA, max, you have 0.48 Watts, so it will get hot..... 
 Harry

FormerMember · Answer

newengg, 
 You could consider switching to the ADA4948-1 or the AD829, both have lower supply current. 
 Harry

FormerMember · Answer

Just change to an ADA4084-1, ADA4610-1, or AD8671 and the power dissipation will 
 be a lot less. 
 Harry

EZAdministrator · Answer

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Heat problem in AD811ANZ