# Time Voltag e Voltag e Sources Generate Sine

Time Voltag e Voltag e Sources Generate Sine Waves Frequency Oscilloscope Spectrum Analyzer This is the ideal output: most specs deal with deviations from the ideal and adding modulation to a sine wave Microwav e RF 3-6 GHz Source Basics Millimete r 20-50 GHz 300 GHz Copyright

2000 Types of Sources CW generates a single frequency, fixed sine wave Swept sweeps over a range of frequencies may be phase continuous Signal Generator adds modulation produces real world signal Source Basics Copyright 2000 CW Source Specifications ...Frequency

Range: Range of frequencies covered by the source Resolution: Smallest frequency increment. Accuracy: How accurately can the source frequency be set. EXAMPLE Voltage Uncertaint y + _ f CW * agin * cal g f CW = CW frequency = 1 GHz agin = aging rate = 0.152 ppm/year g cal = time since last calibrated = 1 year Accuracy+ _= Frequency Source Basics

Accuracy = 152 Hz Copyright 2000 CW Source Specifications ...Amplitude Range (-136dBm to +13dBm) Accuracy (+/- 0.5dB) Resolution (0.02dB) Switching Speed (25ms) Reverse Power Protection Source protected from accidental transmission from DUT What is P max Voltage

DUT out? How accurate is this number? min What is P Frequency Source Basics Copyright 2000 out? CW Source Specifications ...Spectral Purity Phase Noise Residual FM Spurious Residual FM is the integrated phase

noise over 300 Hz 3 kHz BW CW output non-harmonic spur ~65dBc phase noise subharmonics 0.5 f0 Source Basics harmonic spur ~30dBc f0 2f0 Copyright 2000 CW Source Specifications Power Spectral Density ... Spectral Purity: Phase Noise CW output measured as dBc/ Hz

frequenc y TRACE A: 75 dBc/Hz Ch1 PM PSD A Marker 10 000 Hz LogMag 5 dBc/div -105 dBc/Hz -125 dBc/Hz Source Basics 1k 10k 100k Copyright 2000 RF CW Block Diagram Synthesizer Section Frac-N

Phase Detecto r ALC Modulato r Output Attenuato r VCO divid e by X Referenc e Oscillator Reference Section Source Basics Output Section ALC Driver

ALC Detector ALC = automatic level control Copyright 2000 RF CW Block Diagram Reference Section to synthesizer section Phase Detecto r divid e by X Optional External Reference Input Aging Rate Temp. Line Voltage Source Basics Reference Oscillator (TCXO or OCXO)

TCXO +/- 2ppm/year OCXO +/- 0.1 ppm /year +/- 1ppm +/- 0.01 ppm +/- 0.5ppm +/- 0.001 ppm Copyright 2000 RF CW Block Diagram Synthesizer Section ...produces accurate, clean signals N= 93.1 Front panel contro l Frac-N 5MH

z Phase Detecto r X VCO 5MH z from reference section Source Basics 2 multiplie r to output section 931 MHz 465.5 MHz Copyright 2000

RF CW Block Diagram Synthesizer Section nois e PLL / Fractional - N ...suppresses phase noise referenc e oscillato r phase noise of source phase detector noise 20log N VCO noise Source Basics phase-locked-loop (PLL) bandwidth selected for optimum noise

performance broadban d noise floor frequenc y Copyright 2000 RF CW Block Diagram Output Section ALC maintains output power by adding/subtracting power as needed from synthesize r section ALC Modulato r

Output Attenuato r source output Output Attenuator mechanical or electronic provides attentuation to achieve wide output range (e.g. -136dBm to +13dBm) ALC Driver ALC Detector ALC = automatic level control Source Basics Copyright 2000 Wave CW Block Diagram Reference Section

Frac N Phase Det ALC Modulato r VCO Sample r by X Ref Osc Phase Detecto r Frac-N Phase Detecto r YIG Oscillato r

Tunin g Coils Synthesizer Section Source Basics Output Attenuato r VCO ALC Driver ALC Detector Output Section Copyright 2000 Applications & Critical Specifications Local Oscillator phase

noise frequency accuracy Amplifier Distortion spurious TOI (for system) Receiver Testing Spurious Source Basics spurious level accuracy Copyright 2000 Applications & Critical Specifications As a Local Oscillator DUT IF signal

poor frequency accuracy will cause transmitter to be at the wrong frequency Source Basics transmitter output poor phase noise spreads energy into adjacent channels Copyright 2000 Applications & Critical Specifications Amplifier Testing f1 DUT Intermodulation Distortion output RF f2 amplitud

e f1 f2 isolato r test system third order products will also fall here spurious signals from source can corrupt measurement fL = 2 f1 fU = 2 f2 f2 f1 frequenc Source Basics y Copyright 2000 Applications & Critical Specifications Receiver Testing Receiver Selectivity in-channel signal (modulated signal)

IF signal out-of-channel signal (CW or modulated signal) DUT source output IF Rejection Curve Level (dBm) spur from source and/or high levels of phase noise can cause a good receiver to fail Frequency Source Basics Copyright 2000 Applications & Critical Specifications Frequency Response

Amplifier Compression Source Basics Frequency Accuracy Output Power (Level) Accuracy Flatness Speed residual FM Power Range Copyright 2000 Applications & Critical Specifications Amplifier Compression Power Range Power Out 1 dB compression point Power In

The 1 dB compression point is a common amplifier specification used to identify the linear operating range of an amplifier. Power sweep is available on some Agilent sources. Source Basics Copyright 2000 Signal Generators Calibrated modulation Analog (AM, FM, PM, Pulse) Digital (I-Q) Format Specific(TDMA,CDMA, etc.) Source Basics Copyright 2000 Modulation ...Where the information resides f(t) + (t)] V= A(t) sin[2 AM, Pulse

FM P M V= A(t) sin[ (t)] Source Basics Copyright 2000 Modulation: Analog Amplitude Modulation Voltage Carrier Time Important Signal Generator Specs for Amplitude Modulation Modulation

Source Basics Modulation frequency Linear AM Log AM Depth of modulation (Mod Index) Copyright 2000 Modulation: Analog Frequency Modulation c f t + V= A sin[2 Important Signal Generator F /F m(t)] dev Specs for Frequency Modulation mod Voltage

Time Source Basics Frequency Deviation Modulation Frequency dcFM Accuracy Resolution Copyright 2000 Modulation: Analog Phase Modulation V= A sin[2 c f t + m(t)] = Voltage peak Important Signal Generator

Specs for Phase Modulation Time Source Basics Phase deviation Rates Accuracy Resolution Copyright 2000 Modulation: Analog Pulse Modulation T Rate=1/T Important Signal Generator Specs for Pulse Modulation Power Rise time

Pulse On/Off ratio t Time Width Power 1/ T Source Basics Pulse width Pulse period On/Off ratio Rise time 1/

t Copyright 2000 Digital Modulation ...signal characteristics to modify Amplitude Frequency Phase Both Amplitude and Phase Source Basics Copyright 2000 Digital Modulation Polar Display: Magnitude & Phase Represented Together ag M Phase 0 deg Source Basics

Magnitude is an absolute value Phase is relative to a reference signal Copyright 2000 Digital Modulation Signal Changes or Modifications ag M Phase Magnitude Change Both Change Source Basics 0 deg Phase Phase Change 0 deg 0 deg

0 deg Frequency Change Copyright 2000 Digital Modulation ...Binary Phase Shift Keying (BPSK) ft + (t)] V= A sin[2 (t) = 1 2 Source Basics Copyright 2000 Digital Modulation BPSK IQ Diagram Q 1

0 I One Bit Per Symbol Symbol Rate = Bit Rate Source Basics Copyright 2000 Digital Modulation ...Quadrature Phase Shift Keying (QPSK) ft + (t)] V= A sin[2 (t) = 1 = 3 /4 2 = 3 = /4 - =/4 4 - 3 /4 Source Basics Copyright

2000 Digital Modulation QPSK IQ Diagram 0 1 Q 0 0 I 1 1 Source Basics 1 0 Copyright 2000 Digital Modulation /4 DQPSK IQ DiagramQ I Source Basics Copyright 2000

Digital Modulation Modulation Accuracy Q Magnitude Error (IQ error mag) { Test Signal Error Vector Ideal (Reference) Signal Phase Error (IQ error I phase) Source Basics Copyright 2000 Applications and Critical Specifications Analog and Digital

Receiver Sensitivity Receiver Selectivity phase noise spurious spectral accuracy Spectral Regrowth Source Basics frequency accuracy level accuracy error vector magnitude ACP performance Copyright 2000

Applications and Critical Specifications Receiver Sensitivity Frequency Accuracy frequency inaccuracy amplitude inaccuracy Want to measure sensitivity in a channel Measurement impaired by frequency inaccuracy input for signal generator DUT Source Basics Copyright 2000 Applications and Critical Specifications Receiver Sensitivity

Level Accuracy Customer is testing a -110 dB sensitivity X= Failed unit pager: X -110 dB specification X X X X O Actual output power= -114 dBm Set source to -115 dBm Frequenc y Case 1: Source has +/-5 dB of output power accuracy at -100 to -120 dBm output power. Source Basics Power Out Power Out

O=Passed unit X -110 dB specification X O O O O Set source to -111 dBm Actual output power= -112 dBm Frequenc y Case 2: Source has +/-1 dB of output power accuracy at -100 to -120 dBm output power. Copyright 2000 Applications and Critical Specifications Receiver Sensitivity Error Vector Magnitude (EVM) e.g. TETRA Signal /4 DQPSK

EVM < 1.0% Source Basics Error Vector Copyright 2000 Applications and Critical Specifications Receiver Selectivity Phase Noise Spurious in-channel signal (modulated signal) IF signal out-of-channel signal (CW or modulated signal) DUT IF Rejection Curve Level (dBm) spur from source and/or high

levels of phase noise can cause a good receiver to fail Frequency Source Basics Copyright 2000 Applications and Critical Specifications Receiver Selectivity Spectral Accuracy: EVM ACP Source Basics GSM Signal 0.3GMSK Copyright 2000 Applications and Critical Specifications Spectral Regrowth ACP Performance

DUT Output from amplifier Input from signal generator Source Basics Copyright 2000

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