help: Sampler circuit

[sawaak]

sampler circuit

Hi,
i need to design a circuit to sample an analog waveform(sine wave). which circuit i should use to do this task. i want to do it using discrete components.

thanks
sawaak

 

[maxwellequ]

circuit sampler

You can try to make a discrete version of the CMOS SHs used in IC's. You just need a MOS opamp, some CMOS switches and capacitors. However you will be limited in the achievable sampling and input frequencies.

The exact architecture depends on several factors:
- Input and output voltages single-ended or differential ?
- What level of distortion can you allow ?
- ...

Regards

 

[sawaak]

basic sampler circuit

Hi,
my requirment is input and output voltages single-ended and i am not so carefull about distortion level, just i can see the correct operation on oscilloscope. same is the case with achievable sampling and input frequencies.
can u give me any specific circuit diagram for this task???

thanks
sawaak

 

[maxwellequ]

sampler circuit

If you just want to see the operation of the SH, and you don't have requirements regarding fin, fs and THD, you can just use a switch followed by a capacitor. You should use a buffer (opamp in unit gain configuration as a buffer - use one MOS input opamp to avoid capacitor discharge).

There are other solutions, which avoid things like signal dependent charge injection. You can check Razavi's "Principles of Data Comversion System Design" book for a tutorial on this.

Regards