Design Of On Chip Adaptive Clock Oscillater

MIPI-DSI(Alliance Specification for Display Serial Interface)is a type of Serial video interface and is used in Mobile electronic equipments.This interface is widely used for display-connecting of mobile terminals just like mobile phones and tablet computers.Compared to conventional parallel transmission interface,the method of using the MIPI-DSI can reduce the number of connections and EMI(Electro-Magnetic Interference).And the high-speed mode of MIPI-DSI is used to transmit data stream,the low-speed mode is used to transmit control commands of display and read the status informations of display chip.The display chip connects with driver chip by bidirectional serial communication in the low-speed mode that requires two chips meet matching baud rates.To make the display chip can automatically match the communication environ ment of different baud rates in the low-speed transceiver module,we need an adaptive clock source.The circuit design in this paper has an adaptive on-chip clock oscillator that provide incentives to the low-speed transceiver of MIPI-DSI circuit.Firstly,this paper analyzes the MIPI-DSI protocol to understand the protocol layer,encoding mode and signal specification.And especially details low-speed model of the MIPI-DSI part including sorting out the synchronization established,data reception,data encoding format and returning the specific process to find out the baud rate range.According to the baud rate,indexes of adaptive clock oscillator in this paper will be figured out.Then,This paper compares the several schemes by the baud rate detection,adjustable oscillator and adaptive adjustment method to identify the design path that using the delay chain method to baud rate detection,using DCO(digital-controlled oscillator)to realize turn-able oscillator.Finally,realization of delay chain baud rate detection,DCO and adaptive algorithm,will be discussed in detail.The design,simulation and verification of adaptive on-chip clock oscillator overall circuit in smic18 technology will be completed.Through the Virtuso tool,the layout drawing and verification work will be completed too.The circuit will be tested after tape out.The results show that the circuit can meet the requirements of adaptive clock in the range of MIPI-DSI low speed baud rate.