UADC4 Universal Analog to Digital Converter for ZERO IF receivers - PowerPoint PPT Presentation

UADC4 Universal Analog to Digital Converter for ZERO IF receivers by Alex Artieda, ZS6EME EME Conference 2018 18/08/2018 1 Alex Artieda, ZS6EME

Agenda • Introduction • Are ZERO IF receiver ‘old Technology’? • PC Audio cards are for music, limiting factor • UADC4 design – ADC – Buffer stage – Clock – PCB layout (4 layers) • UADC4 performance • Questions? EME Conference 2018 18/08/2018 2 Alex Artieda, ZS6EME

Are ZERO IF receiver ‘old Technology’? • Mixers create always unwanted signals • Phase noise in the LO affect ‘reciprocal mixing’ • DDC enthusiast said YES!! It’s old technology DDC Promise • Sampling on the antenna • Use of NCO (Numerical controlled oscillator) • Big amount of band width....in milliseconds • Phase noise and reciprocal mixing are not problems any more. Cool!!!, looks promising...BUT.... EME Conference 2018 18/08/2018 3 Alex Artieda, ZS6EME

Are ZERO IF receiver ‘old Technology’? DDC Promise • Perspective for amateur radio communications - Sampling big amount of BW, is necesary?, MORE is better? - What about Dynamic range?..MORE is always better - What the market can delivery today? - Implementation cost? DDC Technology, today, lack of enough Dynamic Range and have excess of BW for amateur radio applications EME Conference 2018 18/08/2018 4 Alex Artieda, ZS6EME

PC Audio cards are for music, limiting factor • For more then 20 years Amateur radio operators use PC Audio cards ‘as ADC’ units, success was great until those audio cards cannot add any bit more of performance Why? Audio cards, even with sampling at 24bits, limit their best characteristics to just 20KHz of band width Our ears and brains cannot process signal beyod that limit. Why manufactures will extend perfect performance over that limits? EME Conference 2018 18/08/2018 5 Alex Artieda, ZS6EME

PC Audio cards are for music, limiting factor THE LIMIT IS THERE!! JUST 20KHz OF GOOD PERFORMACE THE REST IS JUST MARKETING!! EME Conference 2018 18/08/2018 6 Alex Artieda, ZS6EME

UADC4 Design • The ADC • Sampling up to 768 KHz, 32 bits • Keep excellent performance up to 192KHz, 24 bit • Up to 121 dB dynamic range in single mode. • Up to 124 dB dynamic range in 4 to 2 • Up to 127 dB dynamic range in 4 to 1 EME Conference 2018 18/08/2018 7 Alex Artieda, ZS6EME

UADC4 Design • Buffer stage by the Manufacture Not really a good one!! EME Conference 2018 18/08/2018 8 Alex Artieda, ZS6EME

UADC4 Design • Clock EME Conference 2018 18/08/2018 9 Alex Artieda, ZS6EME

PCB Layout (4 layers) Signal layer EME Conference 2018 18/08/2018 10 Alex Artieda, ZS6EME

PCB Layout (4 layers) Power Layer EME Conference 2018 18/08/2018 11 Alex Artieda, ZS6EME

PCB Layout (4 layers) GND2 Layer EME Conference 2018 18/08/2018 12 Alex Artieda, ZS6EME

PCB Layout (4 layers) Signal2 Layer EME Conference 2018 18/08/2018 13 Alex Artieda, ZS6EME

UADC4 Performance • All test done with the support of Leif SM5BSZ • UADC4 proto3 has excellent flat noise response up to 192KHz • Harmonics are aprox 85dB attenuated. • Cross talk about -110dB • Using the WSE converters the noise floor improve 10 to 15dB • Using the IQ+ modified improve is 11dB • Dynamic range in the range of 121dB EME Conference 2018 18/08/2018 14 Alex Artieda, ZS6EME

UADC4 Performance Comparative results with PC sound cards is available at: http://www.sm5bsz.com/linuxdsp/hware/ensemble.htm Videos in YouTube: - https://www.youtube.com/watch?v=b13k78oERpI - https://www.youtube.com/watch?v=YGF8dofRWO8 - https://www.youtube.com/watch?v=hS6MymYLh1Q EME Conference 2018 18/08/2018 15 Alex Artieda, ZS6EME

Questions? EME Conference 2018 18/08/2018 16 Alex Artieda, ZS6EME