ASIC- und Mikrosensoranwendung Chemnitz

Interpolation Circuit AM-IP4k



Interpolation rate 4 … 4096
Input frequency max. 220kHz
Input range 75mVpp … 1000mVpp
Adjustable input low pass filter 10kHz … 250kHz
Constant delay time for all resolutions
Patented internal gain and offset control

Signal shape correction
Jitter suppression
Output signals: ABZ, SPI, SSI
EEPROM, multiturn counter, reference mark adjustment
Power supply 3.3V
Temperature range: -40°C … +125°C

The interpolation circuit AM-IP4k serves to increase the resolution of incremental position and angular measuring systems with sinusoidal output signals. The input signals are subjected to a AMAC-patented internal gain and offset control and the signal period will be divided from 4 up to 4096 times. The ICs comprise three instrumentation amplifiers with adjustable gain factors. Incremental encoders which possess a voltage interface and measuring bridges up to 1Vpp can be connected directly. Sensors with current interface and photodiode-arrays are adapted by a simple external circuit. The IC operates with both single-ended or differential input signals. The noise of the sensor signals is prevented by a switching analog filter. Additionally, a digital hysteresis can suppress the edge noise of the output signals at low input frequencies and at standstill. The AM-IP4k is the first AMAC interpolator with implemented jitter suppression filter for ABZ outputs. The quality of the signals issued by the sensors is monitored in the ICs. For that purpose it is possible to activate 9 different error signals indicating the type of the error. For the calculation of the position a set of sensor or scale specific coefficients for a 360 degree correction (rotary encoder) and a signal shape correction (both linear and rotary encoder) can be placed in the EEPROM of the IC. In that way, harmonics of the sinusoidal signals or inaccuracies of the measuring scale do not lead to errors in the position value.
The three integrated output interfaces ABZ, SPI, SSI and further features like the multi stage trigger signal processing, integrated timer, integrated multiturn counter, the processing of distance coded reference marks, the possibility to adjust the reference mark as well as adjustment and storage of the zero position make the ICs suitable for direct use in industrial controls or in fast multi-channel positioning measuring systems. With these features the ICs are also prepared for use in absolute positioning measuring systems. The AM-IP4k can be configured according to specific applications using the integrated EEPROM or via the serial interface (SPI).

Technical Data


Analog input

Sinusoidal / cosinusoidal / reference (index) signals, differential or single-ended
Adjustable amplification for 1 Vpp / 500 mVpp / 250 mVpp / 75 mVpp
Input frequency max. 220kHz for all resolutions


90° square-wave sequences (A/B/Z)
Adjustable width of zero signal Z to ¼ or 1 period A/B
Service signals for sensor adjustment


30-bit counter value / 16-bit multiturn value / 9-bit sensor state
Up to 25MHz, compatible to Standard-SPI 16 bit
Up to 500 000 measurement values per second
Signal filter for suppression of disturbances


30-bit counter value / 16-bit multiturn value / 2-bit sensor state
Gray code / binary code
Adjustable timing, SSI ring operation
Interface width configurable for 20bit or 32bit. Up to 5 MHz

Interpolation / Signal Processing

Interpolation rate

4 … 4096
user-defined interpolation table storable in EEPROM

Signal correction

Patented digital controller for the offset, control range ±10% of the standard amplitude
Patented digital controller for the amplitude, control range 60% … 120% of the standard amplitude
Digital potentiometer with 64 steps for phase correction; selectable range ±5° or ±10°
Input signal monitoring with configurable error indication
360 degree correction (rotary encoder)
signal shape correction within Sin/Cos period (both linear and rotary encoder)
correction coefficients storable in EEPROM

Suppression of disturbances

Adjustable low pass filter 10 kHz, 75 kHz, 250 kHz
Digital hysteresis for suppression of the edge noise at the output
Selectable minimum edge distance at the output (bandwidth limitation)

Reference signal processing

Adjustable reference mark position in 32 steps 0 … 360°
Definition of the optimum reference position via SPI or service signals
Processing of distance coded reference marks
Measured-value trigger at the reference mark position


2-stage measured value trigger
Zero-signal and teach-signal for adjustment and storage of zero position of the sensor
Multiturn counter
Constant delay time for all resolutions
controlled current output
configuration via Integrated EEPROM or SPI interface

Important Characteristics


QFN56 (8 x 8 mm)

Operating Voltage


Temperature Range

-40 … +125°C





50410-SW-0-9-2-66-IP4k-monitor Setup

Ordering Information

Product type


Article Number


Interpolation circuit AM-IP4k, QFN56