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+49 371 33 77 - 0

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GEMAC

Gesellschaft für

Mikroe lektronikanwendung Chemnitz mbH

Zwickauer Straße 227

D-09116 Chemnitz, Germany

Date: 20.04.04

Page 5 of 30

Title:

Data Sheet GC-IP200

Name of Document:

43500-DB-2-1-E-IP200.pdf

2

Input Signals

The two input signals for the interpolation function are analogue voltages (sine/cosine) with a sine-shaped

dependency on the measured value (position or angle respectively) with a phase shift of 90° between these

two analogue voltages, related to one period of the scale. A third input signal serves as a reference signal for

determining the zero or reference point of the scale. All the three input signals are processed as differential

signals.

2.1

Analogue Signal Properties

SinP

SinN

Difference Signal Sin = SinP-SinN

Difference Signal Cos = CosP-CosN

CosP

CosN

90° Phase Shift

Angle 0°

Figure 2

Differential Analogue Input Voltage

1)

Maximum Signal Offset Error

100mV

Sine/Cosine Phase Shift

90° (adjustable

10°)

2.2

Signal Correction

The input signals are subject to a automatic gain and offset control patented by GEMAC. The amplitude

controller is specified for a control range of

20% of nominal input voltage. The offset of the external signals

must not exceed a value of

10% of nominal input voltage. The phase shift of the input signals can be

statically adjusted by a external analogue potentiometer in a range of

10° (also refer to Application Notes

4300x-AN-3-0-E-IPx.pdf).

A Chip Reset results in setting the gain-offset-controller to midscale. For achieving the best interpolation

performance, the gain-offset-controller needs approximately 20 signal periods for reaching a steady state.

Until this time, the input signal frequency must not exceed 50% of the specified maximum signal frequency

(refer to chapter 4.4).

All signal errors figures as a union in the IP200. In some special cases means decreasing of one signal error

result in a wider permissible range of another signal error. For achieving the highest performance of the

automatic gain-offset-controller, it is recommended to carefully adjust the phase shift on the connected

sensor itself. This is important especially for high interpolation rates.