Analog-Fronted for Incremental Encoder Signals With Sine and Cosine Outputs Sponsored by BAYTP
eyADC-DG2 is an analog front end for the evaluation of incremental en-
coder with sine/cosine outputs. The chip includes two sign comparators
which control an internal up-down counter. Additionally, the sine/cosine
signals are converted and filtered by continuous time Delta-Sigma ADCs.
The exact angle information obtained by arctan calculation, the raw as
well as filtered modulator output data can be accessed via SPI interface.
Additionally, an integrated sample rate converter allows the access of
the raw data when using an application clock lower then 32MHz.
An LDO, an internal reference voltage generator, and an internal clock
generator provide all important functionalities for implementation of the
ayADC-DG2 into application.
eyADC-DG2
F O R M O R E I N F O R M A T I O N
eesy-ic GmbHSuedwestpark 10-1290449 Nuremberg, Germany
+49 (0)911 810 211 [email protected]
eyADC-DG2 overcomes the disadvantages of
capacitive signal sampling by using continuous
time Delta Sigma modulators. This avoids the
need for further external analog signal process-
ing like input low-pass filtering or common mode
voltage control. The reliability and performance
of the complete system is increased while mini-
mizing complexity and production costs.
The chip’s sinusoidal input signals are directly
fed to resistors, which facilitate a very high input
common mode voltage range. Additionally, resis-
tors allow high linearity due to their low voltage
coefficients.
Continuous time Delta Sigma modulators also
provide the advantage of inherent suppression
of high frequencies: The input signal is oversam-
pled and a low-pass filter is applied afterwards
in digital domain. This provides further immunity
against high frequency distortions.
From Design to Production
The core competencies of eesy-ic GmbH are
IC-design & layout with focus on analog, digital,
mixed-signal and RF integrated circuits; IC-verifi-
cation and characterization as well as IC-produc-
tion test solutions.
Our company prevails in an atmosphere of
innovation and we are constantly seeking new
challenges. We do everything possible to get the
best result and promote our ideas. We constant-
ly strive to redefine our boundaries and set new
standards in our work and in the industry.
The two Delta Sigma modulators are able to reach an SNR of 81dB with an input signal amplitude of 500mV and bandwidth of 500kHz. For a bandwidth of 128kHz the SNR is 92dB. This is of importance as the fi-nal angle can be further low-pass filtered, even if a 500kHz bandwidth is initially required. This additional filtering improves the performance significantly. The input common mode voltage can be varied from -7V to +7V. The maximum supply voltage is 1.98V. The THD is below -104dB and the integral non-linearity is at maximum 6ppm, based on a 1V full-scale input signal. The ADCs provide a 13bit resolution of the input signal. Including the additional coarse resolution obtained by counting of encoder disk slits, the overall resolution can be > 23bit.
A Comprehensive Solution for Phase Measurement in Encoder Applications
Features
2 Delta-Sigma ADCs
2 Sign Comparators
Up-Down Counter
up to 500kHz Signal Frequency
16bit NMC
90dB SNR
> 13bit ADC resolution
high common mode range of +/- 7V
integrated arctan calculation
integrated digital sinc filter