Digital PID controller design in transistor level

[anamika.saha]

Hi,

I have to design a discrete PID controller based digital low dropout regulator (LDO). I am familiar with the theory of PID controller. However, I am confused about the implementation in transistor level. Can anyone please help me on this issue?

Thanks,
Anamika

 

[barry]

Basically you need three blocks: linear gain(P); an integrator(I), and a differentiator(D). Once you figure out how to implement each of those blocks with transistors you can tie them all together to create your controller.

 

[FvM]

Most LDO feedback amplifiers are PI rather than PID. Basic problem is that the controller must be aware of a wide range of possible load impedances, PI parameters are not optimized for a specific "control process" but for worst case conditions. A D term would reduce the stability margin with varying load impedance.

Do you actually mean digital PID? Not sure how you imagine the transistor level implementation of a digital PI or PID controller. It involves at least ADC, DAC and an arithmetic core, either a sequential processor or dedicated parallel numeric processing unit. Asking for the transistor level is identical to ask for recent analog and digital ASIC technology.