Propagation delay

Now let us consider imaging by a lens. The disturbance at a point (, r]) in the image plane is given by a superposition of the disturbances from points x, y) across the pupil A, with appropriate propagation delay,... 

Advantages Accurate, very low propagation delay Disadvantages Can be realized with fewer parts... 

A minimum propagation delay is required for the start-up of this circuit. Make sure the data sheet or SCD of this part has a minimum listed propagation delay. 

The MCP significantly enhances the speed and reduces the power consumption of the system. Because the ICs are spaced closely together, the interconnection length and propagation delay are greatly reduced, and faster clock speeds are possible. The short interconnections also reduce the need for line termination to prevent reflections. Characteristic impedance is better controlled within the MCP, and fewer signal reflection points exist. Finally, the power dissipation of output drivers can be reduced because of the lower resistive losses and capacitive load of the interconnection. 

Propagation Delay of Lossless Lines. The minimum propagation delay (Tpd expressed in picoseconds per centimeter) for a unit length of lossless line is the inverse of the phase velocity (op) of the electromagnetic waves propagating through the dielectric medium surrounding the conductor line ... 

Additional delay may be imposed by the capacitive loading of branch lines, receivers, and bonding pads attached to the interconnection or by the series inductance of vias or wire bonds. If the additional capacitance can be assumed to be uniformly distributed over the interconnection with electrically short spacing (an assumption that is not always valid), the modified propagation delay (Tpd ) is given by (37)... 

Figure 10.6 A waveguide section between two partial sections, a) Physical picture indicating traveling waves in a continuous medium whose wave impedance changes from R0 to Ri to R2. b) Digital simulation diagram for the same situation. The section propagation delay is denoted asz- T. The behavior at an impedance discontinuity is characterized by a lossless splitting of an incoming wave into transmitted and reflected components.

Although minimization in integrated circuits allows for faster device operation, propagation delays increase with increasing numbers of interconnects. To address this problem, lower dielectric constant materials have been prepared. 

The dielectric layers should be thick to achieve low interconnect capacitance (or high characteristic impedance), which reduces the power consumption of driver circuits and the RC delay of the Interconnect. Finally, the dielectric material should have a low dielectric constant (e ) to minimize the propagation delay (which is limited by the speed of light in the dielectric), the interconnect capacitance and the crosstalk between signal lines. 

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