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A Cascoded Source Follower Static Dual-Vcc Level Converter Circuit for High-Performance Microprocessors

IP.com Disclosure Number: IPCOM000029809D
Publication Date: 2004-Jul-13
Document File: 2 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

This paper discloses a novel method for a cascaded Vcc level converter circuit that asynchronously interfaces processors with dual Vcc domains. Benefits include a faster, lower energy solution that eliminates static current.

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A Cascoded Source Follower Static Dual-Vcc Level Converter Circuit for High-Performance Microprocessors

This paper discloses a novel method for a cascaded Vcc level converter circuit that asynchronously interfaces processors with dual Vcc domains. Benefits include a faster, lower energy solution that eliminates static current.

Background

In dual-Vcc microprocessor designs, there are low-vcc (vccl) and a high-vcc (vcch) domains. A low-vcc signal must be level converted to interface with a high vcc domain. A static inverter can not be used to interface a vccl domain to a vcch domain, because it will cause large amounts of static current to flow through the processor (see Figure 1).

General Description

Current level converters asynchronously level signals without static power. Contention is reduced since one of the internal nodes of the cross coupled PMOS is forced to vccl-vt (see Figure 2). However, the disclosed method further reduces contention by splitting out the output driver from the core level converting interface, via a cascoded source follower pre-driver. This allows for a high gain at the output and a low input capacitance (see Figure 3).

Advantages

The following are advantages of the disclosed method:

·        Provides any easy way to interface the different vcc domains asynchronously

·        Eliminates static current

·        Minimizes the delay penalty between low and high vcc domains

·        Is 19% faster and uses 17% lower energy, compared to prior art level converters

Fig. 1

Fig. 2

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