A detailed Numerically controlled low power oscillator using FPGA technique (FIELD PROGRAMMING GATE ARRAY)

1. Er.Prasanna.P
Department of Electronics &
Communication Engineering
Topic : Low Power
Numerically Controlled
Oscillator

2. Numerically Controlled Oscillator
•Oscillator is a device that is mainly used
for controlling purpose.
•Numerically controlled oscillator deals
with the simplifications of arithmetic
operations.
•The application platform used is FPGA.
(FIELD PROGRAMMABLE GATE ARRAY)

3. Purpose of using numerically controlled
oscillator
• Utilization of less hardware and ultra low
power.
• Less number of memory location to store
phase angles.
• Simple realization techniques are proposed.
• Can obtain any form of trigonometric
relations.

4. Concept of Cognitive Radio or Wireless
devices
• Normally power consumption plays a major
role in wireless devices.
• The amount of power dissipated for a wireless
mode communication is much., considering a
wired communication.
• Large amount of memory elements are
equipped.

5. Technique in NCO
• GSM standards require average frequency
requirement of carrier which should be better
than receiving base stations.
• To achieve high frequency an automatic
frequency control through handset baseband
is used.

6. Baseband – Generation
• Corresponding digital codes are generated
that varies oscillation frequency until desired
frequency oscillation is achieved in NCO’s
• In integrated NCO’s some spurs takes places
and its much difficult to deal with.
• Crystal harmonics are used to couple radio
frequency.

7. NCO – LOOK UP TABLE
• Most NCO’s uses complex look-up table to
store phase values.
• Storing phase values increase area complexity
and power consumption
• PROPORSAL OF NCO’s USES CONSECUTIVE
ANGLE TO GENERATE NEXT PHASE VALUE.
• Due to this overall consequtive complex
mechanisms are reduced

8. PROPOSED NCO ARCHITECTURE
z-1
Sin ((n+1) °)
Cos ((n+1) °)
z-1
Cos (1°)
Cos (1°)
Sin (1°)
Sin (1°)
-1

9. OPERATIONS IN NCO’s
• Trigonometric popular formulae :
• sin(A+B)=sin(A).cos(B) + cos(A).sin(B) --- (1)
• cos(A+B)=cos(A).cos(B) -sin(A).sin(B) --- (2)
• Values predicted:
• Sin(0°)=0 ; cos(0°)=1
• Sin(1°)=0.017452 ; cos(1°)=0.999848

10. Operation with values
• For Ɵ=2°, n=1 and α=1°
• sin(A+B)=sin(A).cos(B) + cos(A).sin(B)
• sin(1°(1+1))=sin(1°).cos(1.1°)+cos(1°).sin(1.1°)
o = (0.017452 x 0.999848) + (0.999848 x 0.017452)
• = 0.01745 + 0.01745
• Note : {A=α and B=n.α}, the phase angle is
calculated for the range of 360° since 0≤n≤359.

11. Pictorial Representation
Sin 0 Cos 0
Sin 1 Cos 1
____________________________________OUTPUT_____________________________
- Represents value predicted
Represents the next value given as input for the sequence

12. Schematic explanation
• The table illustrates that the values of sin0 and
sin1 are predicted already.
• The look up table process the third input with
the second output and the third output
replaces the second input and the third output
is stored.
• Similarly the other values are obtained with
the predicted output.

13. Signal obtained during processing
5 hertz from NCO proposed

14. 1 Ghz from proposed NCO

15. Questa sim simulation setup

16. Power consumption report
• The estimated power consumption proposed
by NCO consumes a very little power of 52
milli Watt.
• This is considered to be an extremely small
amount of power compared to any other
applications.
Total estimated power
consumption
52 m W

17. Conclusion
The proposed NCO consumes very less power
due to less number of look-up table usages.
Power consumption is important criterion in
portable handheld communication devices.
This proposed NCO architecture is suitable not
only for Cognitive Radio applications but also
almost all power hungry applications.

18. •Thank you 
&
Queries ??