Clock Distribution Scheme using Coplanar Transmission Lines

Abstract

The current work describes a new standing wave oscillator scheme aimed for clock propagation on coplanar transmission lines on a silicon die. The design is aimed for clock signaling in the Gigahertz range (we are able to achieve clock rates of 8GHz and above). The clock is transported as an oscillatory wave on a pair of conductors. An oscillatory standing wave is formed across a transmission line loop, which is connected beginning-to-end through a Mobius configuration. A single cross coupled inverter pair is required to maintain oscillation across the ring. The design is aimed to achieve low skew, low power and extreme high frequency global clock situations. The energy recycling nature of a standing wave along a transmission line allows us to keep very high frequencies oscillations along a conductor with almost no power consumption at all. A special wide input range driver was designed to convert the differential signals on the coplanar transmission lines into a square clock pulse for standard clock sinks. The design uses CMOS 90nm BSim3v model cards for all simulations, with the transmission lines implemented on Metal8.

PEEC based parasitic modeling for power analysis on custom rotary rings

“…In this setup, the parasitics due to the corner and the gap segments are neglected (which is the state of the present research in [2,12,14]). The clock waveform obtained for this setup is shown in Fig.…”

“…The frequency of each rotary ring is given by (2), which depends on the circuit parasitics in (3) and (4). In particular, the inductance of the rotary ring depends on the perimeter of each ring, the interconnect width (w ), interconnect thickness (t) and the separation between the inner and outer interconnects (s).…”

“…Unlike the pioneering study in [12], which uses RLC models, previous studies in [14] and [15] adopt transmission line models for power analysis and design size optimization, respectively. In [2], a U-element based SPICE model is proposed, which also accurately captures the transmission line behavior as well as incorporating mutual inductance and mutual capacitance. However, similar to [14] and [15], the parasitics of the corner and the gap elements in the rotary rings are ignored.…”

ZeROA: Zero Clock Skew Rotary Oscillatory Array

“…2) from a tapping point i is computed as 2 i (x; y) = i + [l i (x; y)] (5) where i is the phase at the tapping point TP i on the ring and [l i (x; y)] is the delay of the tapping wire of length l i (x; y). Length li(x; y) is defined as the Manhattan distance between the tapping point TP i and the registered at location (x; y).…”

Flexible and Reconfigurable Mismatch-Tolerant Serial Clock Distribution Networks

“…5) Standing and Travelling Wave Networks: A standing wave clock network superimposes a sinusoidal forward phase clock with a reverse phase clock produced by reflecting the forward clock off of a ground termination at the opposite end of the conductor [22]. This approach results in fixed phase clock signals at every tap with varying amplitude [23], depending on the location of the tap.…”