The goal of this project is to test frequency aspects of the ADF 4350 synthesizer using the...

The goal of this project is to test frequency aspects of the ADF 4350 synthesizer using the EVAL-ADF4350 evaluation board.

In order to achieve the goal, we had to learn how to utilize the HP 8133A 3Ghz pulser to learn about the infiniium DSO80204B 6Ghz osiloscope.

We first needed to study theoretical square waves:

1

4 1( ) sin 2 1 2

2 1squarek

x t k ftk

1 GHz, log scale (dB)

0 1 2 3 4 5 6 7 8 9 10

x 109

-120

-100

-80

-60

-40

-20

0

X: 2.995e+009Y: -8.522

FFT of 1GHz squre wave (50% duty cycle)

Frequency (Hz)

20*l

og|Y

(f)|

MATLAB theoretical results: Scope’s practical results:

We examined the output signal in the time and frequency domain.

Time domain Frequency domain1.5 GHz1.8 GHz

In order to find a stabilization time constant of the PLL, we toggled between 2 frequencies and measured the variation time.

Low frequencies, high jump: 1.3 GHz to 650 MHz

Center frequencies, low jump: 1.8 GHz to 1.5 GHz

High frequencies, average jump: 2.25 GHz to 3.6 GHz

We concluded that:Beginning frequency (GHz) End frequency (GHz) Frequency gap (GHz) Time delay

(nanosec)

1.3 0.65 0.65 5.24

1.5 1.8 0.3 8.156

2.25 3.6 1.35 5.378

We checked the linear frequency variation – the ability to generate signals whose frequency is changing in a controlled manner.

Example:

Here are the results of the frequency sweep from the scope:

Time domain: Frequency domain:

1 GHz1.1 GHz1.2 GHz1.3 GHz1.4 GHz1.5 GHz

As can be seen in the image, the first harmony changes between 1GHz and 1.5 GHz during a period of 5msec: 1500 1000

1 sec 5 sec100 ( )

MHz MHzm m

MHz spacing

We also tested other frequencies. The above is between 1.5 GHz and 2 GHz during a period of 5msec: 2000 1500

1 sec 5 sec100 ( )

MHz MHzm m

MHz spacing

2. We can toggle between frequencies adequately. The toggling time rests approximately between 8 ns and 5 ns.

1. The VCO produces an adequate square wave for frequencies of over 800 MHz. Lower than 800MHz we’re getting into low frequency problems of the VCO.

3. The synthesizer is able to generate a linear frequency sweep.

1.If this VCO is used as a linear frequency sweep transmitter, it couldn’t perform sweeps of under 1msec spacing with current software.

2.The real limit of the device is measured to be between 5ns and 8ns, and therefore linear sweep spacing could be narrowed.

3.This VCO’s software cannot toggle between operation modes (such as linear sweep, frequency toggling etc.). If needed in the future it is possible to develop a new software.