Browse Prior Art Database

Dynamic Circuit with Multiple Feedback Devices

IP.com Disclosure Number: IPCOM000014646D
Original Publication Date: 2000-Oct-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 4 page(s) / 36K

Publishing Venue

IBM

Abstract

Disclosed is a dynamic circuit that avoids noise-induced failures by using multiple feedback devices. Typically, dynamic circuits have one "weak" feedback to the precharge node maintaining the stored charge, Figure 1.

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Dynamic Circuit with Multiple Feedback Devices

Disclosed is a dynamic circuit that avoids noise-induced failures
by using multiple feedback devices. Typically, dynamic circuits
have one "weak" feedback to the precharge node maintaining the
stored charge, Figure 1.

The charge supplied by the weak feedback device adversely affects
the performance of the circuit. The larger the size of the
feedback device, the greater is the delay through the circuit.
Therefore, the tradeoff between the performance impact of sizing
the feedback larger versus the risk of noise problems if the
feedback device is too small must be made during the design.

It is desired to have some method of providing more feedback
when more is needed and performance is not a concern (for
example, under
reliability stress conditions) and providing less feedback when
less is
needed to maintain function and less is desirable for performance
reasons.

The general topology of a domino logic gate using the invention
is shown in Figure 3. Test input signals (T0, T1,... Tn) are used
to control which extra feedback device(s) P0, P1, P2,,...Pn in
Figure 3 are turned on. The feedback devices can be sized such
that they supply an amount of current to the precharge node (X)
that is proportional to the binary value of the test signals. An
example of this is shown in Table 1. This invention does not
require the binary sizing. To reduce capacitance on the output
node OUT, the devices Pn+1, Pn+2,...Pn+n+1 can be sized small and
P0, P1, P2,...Pn can vary in sizes.

If the test signal is at ground (GND), then the gate-to-source
voltage (VGS) of the pfet gated by that signal is "on" and that
pfet will supply current to the precharge node if the other
device in series with...