Triangular --> Sine wave shaper on an IC

sine shaper

Hi all,
I'm supposed to design a wave shaper to shape a previously generated triangular waveform into a Sine wave.
The design is supposed to be implemented on an INTEGRATED CIRCUIT.
So, does anyone has a good shaper design that fits IC implementation :?:

sine to triangular ic

35 years ago this was done with resistor-diode ladders. As the signal level increased another diode cut in and made a voltage divider divide by a greater amount. Something like 7 diodes each direction would make a sine wave with 1% distortion.

sine wave shaper

If you operate within certain frequency range you may use an active low-pas filtr and, depending on how "nice" sine wave is required, you can implement single- or multi-pole filter ..
Here you can find some examples:
'Active Low-Pass Filter Design"
http://alpha.science.unitn.it/~bassi/Signal/TInotes/sloa049.pdf

If, however, you need to convert triangular signals in a wide frequency range then solultion with diodes suggested by Flatulent is a very interesting option .. see picture below ..

Regards,
IanP

Hi,
I was searching for conversion of triangular wave into sine wave and I found a circuit on eCircuit Center
http://www.ecircuitcenter.com/Circuits/Function_Generator/Function_Generator_2.htm

I checked the circuit on PSpice and it is working but I still dont understand that how the sine waves are coming? The collector current of both the transistors are showing sinusoidal waves for a triangular wave..Please help me understand.
Non linear characteristics like the characteristics for a diode in positive n then in negative direction are combined to give the shape of sine?
Thanks for the help...

-Hemanshu

A differential pair realizes a sinh function, not exactly a sine function, but it can be used as a rough approximation. There's nothing
mysterious involved with it. You can derive the differnential pair's functional behaviour from the basic transistor characteristic, it's
also discussed in literature. What do you want to know particularly?

In addition, parallel circuits of multiple differential pairs can be used to approximate arbitrary analog functions that can be represented as

Hi FvM,

Thanks for replying! Well I honestly didn't know that. Thanks for your guidance.
Actually I was exploring ways of sine generation.

One I implemented was oscillator method, then I saw a circuit generating sine from triangular, implemented it and was working so was thinking the math behind.
Ok, one more method that I saw was having 2 diode network placed parallel to each other. Please see the attached pdf for this.
Any more ideas if you can share for the same would be good

One more request. Please see another circuit at
**broken link removed**

Have you ever used such method? How can we generate sine from square input? can differential amplifier still be used?

Sorry for bugging you with so many questions but you have awesome knowledge man. so just wanna learn from you

Thanks again
-Hemanshu

I've used different sine generator principles depending on the design purpose. E.g. a fixed frequency generator can be easily
implemented with low-pass or band-pass filtered signal. Triangular-to-sine converter (either diode network or differential
pair) is good for a wide frequency range, because no tuning is involved. RC or LC sine generators are preferred for high signal
quality, but tuning of at least two components is required for a wider frequency range.

Today, digital methods (DDS generator) are cutting out the signal quality of most analog generators, covering an at least several ten,
partly multiple hundred MHz frequency range.

hey FvM, any material/site you would like to refer for further reading on this topic.
I was working with diodes for generation of sine wave but the circuit is still not working. I will try to debug it n will post here then.

Thanks for your continuing support...

The original idea for the shaper is from Barrie Gilbert.

Results in the 83er IC-Line

Intersil ICL 8038
Exar EX8038
Maxim Max038

all using the same principle.

Here is an example for the shaper in lateral-pnp for CMOS

**broken link removed**

The key point to have low distortion over the hole frequency band is that the switching voltages for the triangle-generator should be matched to the scale of the shaper over temperature and process spread.

I remember a patent on this but shure it is outdated

@rfsystem/FvM
Can you please advice something on this

abbeyromy,

do you intend to built the shaper with discrete components or do want to built an IC?

hi all.

im doing my project in circuts and is about a signal generator using operational amplifier...and had a trouble making its schematic diagram..

can anyone help me with this matter..

thanks..

Hi kulit,

don't you think its better to open a new topic (in your own interest), because your question is directed to an oscillator rather than to a shaper circuit?