Oscillator Design - any recommendation

Need to design an oscillator 500K~10MHz range. -5V to 5V amp.. rise time and fall time should be lesser than 5ns.

freq resolution is not an issue. rise and fall time and -5to +5 voltage are important criteria.

Initial idea was to generate the frequency using a PLL or VCO chip (get 0-5V swing) then use high precision op-amp to get the negative swing.

Rise and fall times are way over 5ns when using the high-precision op-amp to generate the negative swing.

Any one used SN74LV4046AN PLL-with-VCO IC from TI?? https://focus.ti.com/docs/prod/folders/print/sn74lv4046a.html

Any pointer on this chip or on the overall approach will be really helpful

Hi,
Only some questions:
Is it a must to have high stability (locked to an XTAL)?
Must you have it (20x frequency adjusting) in one band or in two... ?
Is duty cycle fixed, must be exact at 50%, or some others & adjustable too?
Is output ampl. fixed on +5V to -5V or must be variable?
Is output signal on 50 Ohm to measure?
Should you use a PC/micro to tune it or a potentiometer or DAC?
K.

Is it a must to have high stability (locked to an XTAL)?
No need to locked to an XTAL

Must you have it (20x frequency adjusting) in one band or in two... ?
If possible to get the 20x in one band it would be great, else have to split it down

Is duty cycle fixed, must be exact at 50%, or some others & adjustable too?
duty cycle is fixed at 50% (5-10% variation is acceptable)

Is output ampl. fixed on +5V to -5V or must be variable?
This is fixed, not variable

Is output signal on 50 Ohm to measure?
Yes

Should you use a PC/micro to tune it or a potentiometer or DAC?
No PC/micro.. potentiometer or DAC tuning only

OK anbu,
+/-5V on 50 Ohm means a +/-100mA delivering capability, are you ready for some complexer output stage to build? I think on "Composite amplifier" some discretes & HF Op + DC compensating low speed precision Op...
Your spec of less as 5ns for both edges isnt so full trivial (peak to peak 10V & 3dB bandwith of min. 70 MHz, even if your frequency not more as 10MHz is, but square wave, is not so simple to make) :-( ....
For the oscillator one another OpAmp with duty cycle adjusting/corrective setting for 50% per trimmer pot.
These can be a simple OpAmp with +/- 6...8V supply & the endstage must be minimum from i.e. +/-8...10V supplyed.
K.

Lots of things to do, dint expect that..

Consider, I have the oscillator part with 500K-10M Hz and 0-5V peak-peak. Now, wats the best way to go from 0-5V to -5V to +5V and without any change in the rise and fall time. Will a High-precision opamp as a diff-amp do the job?

No,
The easiest way is_in my opinion_ to use an OpAmp on +/- 5--8V to generate your pulse direct bGND symmetrical_you dont need some pegel shifting(/offset controlling; so ost the part of pulse generator relative simple!
Than, a diff amp isnt bad, but you can not present a inexpensive one what up tu 70--100MHz +/- 5V on 50 Ohm (=100mA ) delivern can! Belive me; composit amp is a good selection...
K.

karesz,
I couldn't understand your last reply clearly. Did you mean not to use an oscillator separately (0-5V) then amplify to -5 to +5 V and use an op-amp directly to get the signal?

Can you explain more on your last reply.. thnks

Exactly;
If an OP is supplyed from +/- 5 or more Volts= your signal will be between +/- x Volts (concrete value is OpAmp model depending)_ what you are wishes...
With a RRIO type it will be between practically +5V and -5V (Puls out ifferences to Usupply are usually 0.1---0.5V, but in older types it can be 1...1,5V or 2V).
K.

Hi,
So, these is (ca.) my oscillator idea, refer pls to page 18:
**broken link removed**
Some important differences:
1,
You NEED another Op type, with high speed capability (have to deliver 10MHz square=must function at 70...100MHz, you can not use the 741 type old one!
Some modern RRIO -or minimum RROutput Type is to elect, with double/bipolar supplying & min. +/_6V capability! Output current capability isnt very interesting here than the "Composite Amp" is a high imp. load (as an OpAmp)...
I would say; order pls such free samples from ADI_AD8675AR (SOIC8) is an excellent amp for these job! These is a component of $2..3,-:**broken link removed**
I see yet; AD8021AR can be better =works really up to ca. 100 MHz instead ac 10-20 only, but maximum with +/-12V! Price is similar as the others. In all cases its in your application not a problem!
2,
I would forget Rb & Rc, but on the right side of both diodes use a smaller value (I think so at 1..10K) trimmer between both diodes, the arm of Trimm poti is to connect to the OpAmp output -instead of diodes common as yet...

If you will design with 100pF & 1...20KOhms it should oscillate in your 20x band of 0.5-10MHz and deliver the wished ca. +/_5V peaks from +/-5-6V supply.
K.

Added after 29 minutes:

Hi Anbu,
I have yet an old, but good description of "Composite Amp", & a version that you should use_in my opinion (from hes "Father: Jim Williams"):
https://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1021,P1222,D4116
Refer pls to Fig.12: these is, not more & not less what your output amplifier specification needs_ if you dont believe it; it will be clear some later _
With best wishes!
Karesz

Silicon osc may work for you
http://cds.linear.com/docs/Design Note/dn293f.pdf

Hi,
Nice-moderne component, but as I understand for these project it needs 4x switching of bands, than it can span maximum a half decade & it delivers only unipolar pulses...
With the OpAmp circuit is real in only one band to tune it & delivers the needed bipolarity originally .
K.

Karesz,

Thnks for your help.

I have another question, if I change my tuning options to PC/uC instead of potentiometer or DAC. What are my options? I cant use regular op-amp design (which I might be using now). When integrating all other circuit elements I think digital tuning will be better and also much precise. So, if i am asked to go for digital tuning mode (give one digital word and you get one frequency, another word for another freq), I should be prepared for that.

Also, most of the ICs are SOP or MSOP packages now. I am searching for DIP packs for testing purpose, before going to PCB designing, but i cant find them. Any suggestions.

Yea, prototyping is every day more problematic if you dont like MSOP or the newer packages...
You must make it with SMD (SIOC 8/16 are nowadays big) often MSOP or CSP like ones.
If you have it to integrate: I think you must have another circuit technique!
I believe; a function generator like circuit is to select & realize_than is premium, that the both current generators (for I+ & I-) are nice to control per DAC, but IT CALLS for MIXED signal ASIC!
Will you have mixed signal ASIC capability?
Do you know function generator circuit technique, i.e. from Wavetek? Its a good stuff/basic for your project (in my opinion)
Another possibility is; you will apply a DDS & some good wide(r) bandwidth output PA (PowerAmp)...
If you are searching for some IC/component _ I see it first very often by https://octopart.com
By their you can see who has it , how much pcs, what kind of price/package + mostly has a pdf datasheet too...
K.

Hi,
I found yet AN47, Jim Williams_High Speed Amplifier Techniques,www.linear.com, check it pls i.e. at pages 45---65... I think, the circuit of page 46 is for what I did searched, its to integrate too_eventually.
K.