• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Help to design 3MHz amplifier

Status
Not open for further replies.

shane_ng

New Member
Who can help me in designing an amplifier with the following characteristics?

1) Ability to amplify signals from DC to 3MHz
2) Use minimum power (less than 25mV)
3) No distortion
4) Have some level of protection
5) Use minimum passive component
6) Gain should be >100,000
7) Power supply (±12V @ ±9V @ ±5V)
8) β= 200-250
9) Value of resistor less than 10kΩ

Thanks a lot ^.^
 

Hero999

Banned
It's proably a homework question which he doesn't fully understand.
 

Hero999

Banned
The origional meaning was probably lost in the translation from Indian or whatever his mother tongue is.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Makes nonsense? I need to design an amplifier circuit to amplify the signal from 0 to 3MHz and also with those characteristics.
As I said, it makes no sense whatsoever - if you want an amplifier then tell us EXACTLY what you're trying to do, if it's homework go back and tell whoever set it he's a complete idiot!.
 

shane_ng

New Member
As I said, it makes no sense whatsoever - if you want an amplifier then tell us EXACTLY what you're trying to do, if it's homework go back and tell whoever set it he's a complete idiot!.
Yes, it's a homework. We all got no idea with it,so i try to search for some helps here. The problem is he's able to design it.
 

crutschow

Well-Known Member
Most Helpful Member
Makes nonsense? I need to design an amplifier circuit to amplify the signal from 0 to 3MHz and also with those characteristics.
Nonsense, yes.
2) Minimum power (less than 25mV). mV is voltage not power.
3) No distortion. All amplifiers have distortion. It's just a question of how much your can tolerate.
7) Power supply (±12V @ ±9V @ ±5V). Does that mean it should operate over the range of ±5V to ±12V
8) β= 200-250. β of what?
9) Value of resistor less than 10kΩ. What resistor?
 

shane_ng

New Member
Nonsense, yes.
2) Minimum power (less than 25mV). mV is voltage not power.
3) No distortion. All amplifiers have distortion. It's just a question of how much your can tolerate.
7) Power supply (±12V @ ±9V @ ±5V). Does that mean it should operate over the range of ±5V to ±12V
8) β= 200-250. β of what?
9) Value of resistor less than 10kΩ. What resistor?
2) minimum power - may be i copied the wrong term
3) No distortion - just have to minimize the distortion
7) Power supply (±12V @ ±9V @ ±5V) - means can use either one, but not operate over the range
8) β= 200-250 - β of the transistor
9) Value of resistor less than 10kΩ - all resistors in that circuit
 

Hero999

Banned
Who can help me in designing an amplifier with the following characteristics?
Sorry but the characteristics you've mentioned make no sense - I'll go through themn and pick at them if it helps you.

1) Ability to amplify signals from DC to 3MHz
Is 3MHz the 3dB point?
2) Use minimum power (less than 25mV)
Power is measured in Watts not V.

Also are you talking about the input power output power?

What's the load impedance?
3) No distortion
Impossible, no amplifier has completely no distortion.
4) Have some level of protection
What level of protection?

Short circuit?

Over voltage?

5) Use minimum passive component
What do you mean by minimum?

Passive components are resistors, capacitors and inductors, is there no limit on active components? Can you use 100 transistors but are limited to say three resistors?
6) Gain should be >100,000
That's a very high gain, is there a maximum gain?

Would it be fine if the gain was 1000,000, 000?

Good luck with achieving a gain of 100,000 at 3MHz.

7) Power supply (±12V @ ±9V @ ±5V)
No mention of current draw.

Besides that's a lot of power supplies, surely ±12V is enough.

8) β= 200-250
What do you mean by that?

Is β the gain or negative feedback? Either way you've previously specified a gain of 100,000 which contradicts this.

9) Value of resistor less than 10kΩ
What resistor, don't you mean the input impedance?

I recommend you politely tell your lecturer that the specification he's given you is total rubbish.:D
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Yes, it's a homework. We all got no idea with it,so i try to search for some helps here. The problem is he's able to design it.
He's certainly not designing it to that spec, others have pointed out the individual reasons why not - this is probably why you all have no idea?.

Assuming those are EXACTLY what he gave you, he shouldn't be teaching an electronics class at all, as he hasn't got the faintest clue.
 

Hero999

Banned
2) minimum power - may be i copied the wrong term
3) No distortion - just have to minimize the distortion
Without specifying a maximum acceptable distortion, its pretty meaningless.

7) Power supply (±12V @ ±9V @ ±5V) - means can use either one, but not operate over the range
Sounds fair enough.

8) β= 200-250 - β of the transistor
How many transistors are you allowed to use?

Perhaps he should have specified that you use a specific transistor.
9) Value of resistor less than 10kΩ - all resistors in that circuit
So you're only allowed to use resistor values of 10k and under?

If you need larger values you'll need to make them by connecting 10k resistors in series. Let's just hope you don't need a 1M resistor.:p

Is there any limit to the range of values you can use, for example could you use an 8k resistor (which no one makes)?
 
Status
Not open for further replies.

EE World Online Articles

Loading
Top