|IDE give Analoge signal and sata gives Digital signal.|
Rubbish. They are both digital, one is parallel and one is serial, but still digital.
The reason that S-ATA was developed was the P-ATA had reached the limit of what was possible with a parallel interface. One the face of it a parallel interface should be faster than a serial interface because it sends data down the line eight bits at a time where as serial sends it down one bit at a time.
But the reality is that with parallel there is a limit as to how fast the data can be sent as timing and the distance between source and destination is critical.
With the advances in hard disk technology, the hard disk was capable of reading data faster than the parallel interface could transfer it it. so the serial interface was devised. Timing is not so critical and it was possible to send data down a serial line at a bit rate that would be impossible with a parallel connection. It is for the same reason that all modern printers have USB serial interfaces, Parallel interfaces on printers are thing of the past.
When SATA was first introduced there was little to chose between P-ATA and S-ATA as the internal hardware was identical. Aa disk technology has advanced, reading and writing speeds have increased and can be made use of without the restriction imposed by parallel interface which would have slowed things down.
Both P-ATA and S-ATA are IDE devices. To call a P-ATA disk IDE to the exclusion of SATA is incorrect. IDE (Integrated Device Electronics) refers to the fact that the disk controller is integrated into the device itself and is not separate as is the case with SCSI drives.