1. Yamin Sheth (100870111019)
Avani Savaliya (100870111020)
Jay Patel (100870111021)

2. OUTLINE
FUNCTION GENERATOR
FREQUENCY SYNTHESIZER
SFG 2000/ SFG 2100 SERIES
DS335- 3 MHz FUNCTION GENERATOR

3. FUNCTION GENERATOR
A function generator is usually a piece of electronic
test equipment or software used to generate different
types of electrical waveforms over a wide range of
frequencies. Some of the most common waveforms
produced by the function generator are the sine,
square, triangular and saw-tooth shapes.

4. FUNCTION GENERATOR
The waveforms generated by a function generator can
be either repetitive or single-shot (which requires an
internal or external trigger source). Integrated circuits
used to generate waveforms may also be described as
function generator ICs.

5. FUNCTION GENERATOR

6. FUNCTION GENERATOR
Other important features of the function generator
are continuous tuning over wide bands with max-min
frequency ratios of 10:1 or more, a wide range of
frequencies from a few Hz to a few MHz, a flat output
amplitude and modulation capabilities like frequency
sweeping, frequency modulation and amplitude
modulation.

7. FUNCTION GENERATOR
Function generators are used in the development,
test and repair of electronic equipment. For example,
they may be used as a signal source to test amplifiers
or to introduce an error signal into a control loop.

8. FUNCTION GENERATOR
Although function generators cover both audio and
RF frequencies, they are usually not suitable for
applications that need low distortion or stable
frequency signals. When those traits are required,
other signal generators would be more appropriate.

9. FUNCTION GENERATOR
A typical function generator can provide frequencies
up to 20 MHz. RF generators for higher frequencies
are not function generators in the strict sense since
they typically produce pure or modulated sine signals
only.

10. FUNCTION GENERATOR
More advanced function generators are called
arbitrary waveform generators (AWG). They use
direct digital synthesis (DDS) techniques to generate
any waveform that can be described by a table of
amplitudes.

11. FREQUENCY SYNTHESIZER
A frequency synthesizer is an electronic system for
generating any of a range of frequencies from a single
fixed time-base or oscillator. They are found in many
modern devices, including radio receivers, mobile
telephones, radiotelephones, walkie-talkies, CB
radios, satellite receivers, GPS systems, etc.

12. FREQUENCY SYNTHESIZER
A frequency synthesizer can combine frequency
multiplication, frequency division, and frequency
mixing (the frequency mixing process generates sum
and difference frequencies) operations to produce the
desired output signal.

13. FREQUENCY SYNTHESIZER
Three types of synthesizer can be distinguished. The
first and second type are routinely found as stand-
alone architecture: Direct Analog Synthesis (also
called a mix-filter-divide architecture) and by
comparison the more modern Direct Digital
Synthesizer (DDS). The third type are routinely used
as communication system IC building-blocks: indirect
digital (PLL) synthesizers including integer-N and
fractional-N.

14. FREQUENCY SYNTHESIZER
Prior to widespread use of synthesizers, radio and
television receivers relied on manual tuning of a local
oscillator.
Variations in temperature and aging of components
caused frequency drift. Automatic frequency control
(AFC) solves some of the drift problem, but manual
retuning was often necessary.

15. FREQUENCY SYNTHESIZER
Since transmitter frequencies are well known and
very stable, an accurate means of generating fixed,
stable frequencies would solve the problem.
Many coherent and incoherent techniques have been
devised over the years. Some approaches include
phase locked loops, double mix, triple mix, harmonic,
double mix divide, and direct digital synthesis (DDS).

16. FREQUENCY SYNTHESIZER
The vast majority of synthesizers in commercial
applications use coherent techniques due to
simplicity and low cost.
Synthesizers used in commercial radio receivers are
largely based on phase-locked loops or PLLs. Many
types of frequency synthesizer are available as
integrated circuits, reducing cost and size.

17. FREQUENCY SYNTHESIZER
The trial and error method was once the work-horse
for designers of frequency synthesizers.
This began to change with the works of Floyd M.
Gardner (his 1966 Phaselock techniques) and
Venceslav F. Kroupa (his 1973 Frequency Synthesis).
Manassewitsch calls this the Brute-force approach.
Techniques and formulae have been provided by
Dean Banerjee.

18. FREQUENCY SYNTHESIZER
Various other mathematical techniques used in the
frequency synthesizer are as follows:
 Gearbox approach: Analogous to the mechanical
gear ratio relationship, the frequency synthesis factor
is composed of multiplicative integers in the
numerator and denominator.
Modulo-N approach

19. FREQUENCY SYNTHESIZER
The block diagram shows the basic elements and
arrangement of a PLL based frequency synthesizer.

20. FREQUENCY SYNTHESIZER
Practical considerations:
In practice this type of frequency synthesizer cannot
operate over a very wide range of frequencies, because
the comparator will have a limited bandwidth and
may suffer from aliasing problems. This would lead to
false locking situations, or an inability to lock at all. In
addition, it is hard to make a high frequency VCO
that operates over a very wide range.

21. FREQUENCY SYNTHESIZER
Further practical aspects concern the amount of time
the system can switch from channel to channel, time
to lock when first switched on, and how much noise
there is in the output. All of these are a function of
the loop filter of the system, which is a low-pass filter
placed between the output of the frequency
comparator and the input of the VCO.

22. FREQUENCY SYNTHESIZER
Thus the design of the filter is critical to the
performance of the system and in fact the main area
that a designer will concentrate on when building a
synthesizer system.

23. SFG 2000/ SFG 2100 SERIES
 SFG-2000 series uses the latest Direct Digital
Synthesis (DDS) technology to generate stable,
high resolution output frequency.
In DDS, the waveform data is contained in and
generated from a memory. A clock controls the
counter which points to the data address. The
memory output is converted into analog signal by a
digital to analog converter (DAC) followed by a low
pass filter.

24. SFG 2000/ SFG 2100 SERIES
The resolution is expressed as fs/2k where fs is the
frequency and k is the control word, which contains
more than 28bits. Because the frequency generation is
referred to clock signal, this achieves much higher
frequency stability and resolution than the traditional
function generators.

25. SFG 2000/ SFG 2100 SERIES
The block diagram is as shown.

26. SFG 2000/ SFG 2100 SERIES
DDS synthesizer consists of Phase accumulator
(counter), lookout table data (ROM), Digital-to-
analog converter (DAC), and Low-pass filter (LPF).
The phase accumulator adds the frequency control
word K at every clock cycle fs. The accumulator
output points to a location in the Table ROM/RAM.
The DAC converts the digital data into an analog
waveform. The LPF filters out the clock frequency to
provide a pure waveform.

27. SFG 2000/ SFG 2100 SERIES
Performance:
• High resolution using DDS and FPGA technology
• High frequency accuracy: 20ppm
• Low distortion: −55dBc
• High resolution 100mHz maintained at full range

28. SFG 2000/ SFG 2100 SERIES
Features :
• Wide output frequency range: 4, 7, 10, 20MHz
• Various output waveforms: Sine, Square, and
Triangle
• TTL/CMOS output
• Counter up to 150MHz high frequency (SFG-2100
series)
• AM/FM with internal and external (SFG-2100 series)

29. DS335

30. DS335
The DS335 is a simple, low-cost, 3 MHz function
generator based on Direct Digital Synthesis (DDS)
architecture.
Basic functions include sine waves and square waves
(up to 3.1 MHz), and ramps and triangles (up to 10
kHz).

31. DS335
All functions can be swept logarithmically or linearly
in a phase-continuous fashion over the entire
frequency range. A rear-panel SWEEP output marks
the beginning of a sweep to allow synchronization of
external devices. Both unidirectional and
bidirectional sweeps can be selected.

32. DS335
Toggling is done either at a fixed, internal rate of up
to 50 kHz, or externally via a rear-panel input.
Outputs have the low phase noise inherent to DDS

33. DS335
Wideband amplifiers maintain good pulse response
and provide low distortion. The result is an output
capable of driving 10 Vpp into a 50 Ω load, or 20 Vpp
into a high-impedance load.

34. DS335
Both GPIB and RS-232 interfaces are available to
provide complete control via an external computer.
All instrument functions can be set and read via the
computer interfaces.

35. DS335
Frequency Range
Sine 3.1 MHz 1 μHz
Square 3.1 MHz 1 μHz
Ramp 10 kHz 1 μHz
Triangle 10 kHz 1 μHz
Noise 3.5 MHz (Gaussian weighting)

36. DS335
Output
Source impedance 50 Ω
Grounding Output may float up to ±40 V
(AC + DC)

37. DS335
Amplitude
Range 50 mVpp to 10 Vpp (50 Ω),
100 mVpp to 20 Vpp (Hi-Z)
Resolution 3 digits (DC offset = 0 V)
Offset ±5 VDC (50 Ω), ±10 VDC (Hi-Z)
Offset resolution 3 digits
Accuracy 0.1 dB (sine output)

38. DS335
General
Interfaces Optional RS-232 and GPIB. All
instrument functions are controllable over the
interfaces.
Non-volatile memory Up to nine sets of instrument
settings may be stored and recalled.
Dimensions 8.5" × 3.5" × 13" (WHD)
Weight 8 lbs.
Power 22 W, 100/120/220/240 VAC, 50/60 Hz.