PRELIMINARY

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Noise

1

σ

Bdiff_typ

Bdiff_max

3

σ

B

ϕ

ϕ

∂

∂B

Phase-Jitter

Figure17: Phase-Jitter

Stochastic Phase Error

∆ϕ

The stochastic phase error includes the error due to the variation of the delay time with

temperature and the error caused by the resolution of the threshold. It can be calculated

in the following way:

d

d

t

n ∆

•

•

°

=

∆

60

360

ϕ

∆ϕ

d

... stochastic phase error due to the variation of the delay time over temperature in °

n

… speed of the camshaft wheel in min

-1

∆t

d

… variation of delay time over temperature in sec

Jitter (Repeatability)

The phase jitter is normally caused by the

analogue system noise. If there is an update of the

offset-DAC due to the algorithm, what could happen

after each tooth, then an additional step in the

phase occurs (see description of the algorithm).

This is not included in the following calculations.

The noise is transformed through the slope of the

magnetic edge into a phase error. The phase jitter

is determined by the two formulas:

(

)

typ

neff

typ

Jitter

B

B

_

_

•

∂

∂

= ϕ

ϕ

(

)

max

_

max

_

neff

Jitter

B

B

•

∂

∂

= ϕ

ϕ