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Function Generator
DS345 — Function & arbitrary waveform generator
  • 1 µHz to 30.2 MHz frequency range
  • 1 µHz frequency resolution
  • Sine, square, ramp, triangle and noise
  • Phase continuous frequency sweeps
  • AM, FM, burst and phase modulation
  • 16,300 point arbitrary waveforms
  • 10 MHz reference input
  • Optional RS-232 and GPIB interfaces


The DS345 Function Generator is a full-featured, 30 MHz instrument that uses an innovative Direct Digital Synthesis (DDS) architecture. It generates many standard waveforms with excellent frequency resolution (1 µHz), and has versatile modulation capabilities including AM, FM, Burst, PM and frequency sweeps. It also generates arbitrary waveforms with a fast 40 Msample/s update rate.

Functions and Outputs

The DS345 Function Generator provides sine waves and square waves at frequencies up to 30.2 MHz, and triangle and ramp waveforms up to 100 kHz. The frequency resolution for all functions is 1 µHz. In addition to the standard waveforms, the unit also provides a wideband (10 MHz) white noise source.

Both the function output and a TTL SYNC output are available through floating, front-panel BNC connectors. Both outputs have 50 Ω output impedances and may be floated up to ±40 V relative to earth ground. The amplitude of all function outputs is adjustable from 10 mVpp to 10 Vpp with 3-digit resolution, and can be displayed in Vp, Vpp, Vrms or dBm. In addition, standard TTL and ECL output levels can be selected.

Additional useful connectors are provided on the rear panel. A trigger input is used to trigger arbitrary waveforms, modulation patterns, sweeps and bursts, while a TTL trigger output is provided to allow synchronization of external devices to sweeps and bursts. A sweep output generates a 0 to 10 V ramp synchronous with frequency sweeps. The sweep marker outputs allow specified portions of a frequency sweep to be highlighted on an oscilloscope.

A 10 MHz rear-panel input allows the DS345 to be synchronized to an external timebase. A 10 MHz rear-panel output allows multiple DS345's to be phase locked.

Modulation

The DS345 Function Generator offers a wide variety of modulation options. It contains an internal modulation generator which can modulate any of its standard waveforms except noise. The modulation waveform can be a sine, square, triangle, ramp or an arbitrary waveform. Modulation rates from 1 mHz to 10 kHz can be selected.

The modulation generator can provide amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). When using AM, modulation depths of ±100 % can be selected with 1 % resolution. Negative values of modulation correspond to Double Sideband Suppressed Carrier (DSBSC) modulation. FM spans can be selected with 1 µHz resolution, and phase modulation can be set between 0° and 7200° with 0.001° resolution.

External Amplitude Modulation

In addition to the internal modulation generator, the output waveform can be amplitude modulated by an external signal applied to the rear-panel AM input. This input is always active—even when other modulation types are turned on.

Burst Modulation

You can generate tone bursts of any output function except noise. In burst mode, the DS345 will output an exact number of complete waveform cycles after receiving a trigger. By adjusting the phase, you can control where in the waveform the burst begins. While using the burst mode, the maximum frequency for sine waves and square waves is 1 MHz, while triangles and ramps are limited to 100 kHz. Burst mode may be used with arbitrary waveforms at any frequency.

Frequency Sweeps

The DS345 Function Generator can frequency sweep any of its function outputs (except noise). You can sweep up or down in frequency using linear or log sweeps. Unlike conventional function generators, there are no annoying discontinuities or band-switching artifacts when sweeping through certain frequencies. The DS345's DDS architecture inherently allows it to perform smooth, phase-continuous sweeps over it's entire frequency range.

Two sweep marker frequencies can be specified. When the sweep crosses either of the marker frequencies, a TTL transition is generated at the rear-panel MARKER output to allow synchronization of external devices.

Arbitrary Waveform Capability

The DS345 isn't just a function generator. It's also a full-featured arbitrary waveform generator. Output waveforms have 12-bit vertical resolution, and can be played back at rates up to 40 Msamples/s.

Since composing complex arbitrary waveforms at the keyboard can be a tedious task, Arbitrary Waveform Composer (AWC) software is provided at no charge. AWC is a menu-based program which lets you create and edit arbitrary waveforms on the screen, store them, and download them to the DS345. Click here for the latest version of the Windows AWC software.

Specifications
Frequency Range
  Max. Frequency Resolution
Sine 30.2 MHz 1 µHz
Square 30.2 MHz 1 µHz
Ramp 100 kHz 1 µHz
Triangle 100 kHz 1 µHz
Noise 10 MHz (Gaussian weighting)
Arbitrary 10 MHz 40 MHz/n (sample rate)
Output
Source impedance 50 Ω
Grounding Output may float up to ±40 V (AC + DC) relative to earth ground.
Amplitude
Range 0.01 to 10 Vpp (50 Ω), 20 Vpp (Hi-Z)
Resolution 3 digits (DC offset: 0 V)
Sine wave accuracy (0 V DC offset)
     5 to 10 Vpp ±0.2 dB (1 µHz to 20 MHz)
±0.3 dB (20 MHz to 30.2 MHz)
     0.01 to 5 Vpp ±0.4 dB(1 µHz to 20 MHz)
±0.5 dB (20 MHz to 30.2 MHz)
Square wave accuracy  
     5 to 10 Vpp ±3 % (1 µHz to 100 kHz)
±6 % (100 kHz to 20 MHz)
±15 % (20 MHz to 30.2 MHz)
     0.01 to 5 Vpp ±5 % (1 µHz to 100 kHz)
±8 % (100 kHz to 20 MHz)
±18 % (20 MHz to 30.2 MHz)
Triangle, ramp, arbitrary accuracy ±3 % (>5 Vpp)
±5 % (<5 Vpp)
DC Offset
Range ±5 V (limited such that |VAC peak| + |VDC| < 5 V)
Resolution 3 digits (VAC = 0)
Accuracy 1.5 % of setting + 0.2 mV (DC only)
±0.8 mV to ±80 mV, depending on AC and DC settings
Sine Wave
Spurious components <-55 dBc (non-harmonic)
Phase noise <-50 dBc in a 30 kHz band centered on the carrier, exclusive of discrete spurious signals
Sub-harmonic <-50 dBc
Harmonic distortion Level
<-55 dBc
<-45 dBc
<-35 dBc
<-25 dBc
 Frequency Range
DC to 100 kHz
0.1 to 1 MHz
1 to 10 MHz
10 to 30 MHz
Square Wave
Rise/fall time <15 ns (10 to 90 %), at full output
Asymmetry <1 % of period + 4 ns
Overshoot <5 % of peak to peak amplitude at full output
Ramps, Triangle and Arbitrary Waveforms
Rise/fall time 45 ns (10 MHz Bessel filter)
Linearity ±0.5 % of full-scale output
Settling time <1 µs to settle within 0.1 % of final value at full output
Arbitrary Waveforms
Sample rate 40 MHz/N, N = 1 to 234-1
Memory length 8 to 16,300 points
Resolution 12 bits (0.025 % of full scale)
Phase
Range ±7199.999° with respect to arbitrary starting phase
Resolution 0.001°
Amplitude Modulation
Source Internal (sine, square, triangle or ramp) or External
Depth 0 to 100 % AM or DSBSC
Rate 0.001 Hz to 10 kHz internal, 15 kHz max. external
Distortion <-35 dB at 1 kHz, 80 % depth
DSB carrier <-35 dB typ. at 1 kHz modulation rate (DSBSC)
External input ±5 V for 100 % modulation, 100 kΩ impedance, 15 kHz bandwidth
Frequency Modulation
Source Internal (sine, square, triangle, ramp or arbitrary)
Rate 0.001 Hz to 10 kHz
Span 1 mHz to 30.2 MHz (100 kHz for triangle, ramp)
Phase Modulation
Source Internal (sine, square, triangle, ramp)
Rate 0.001 Hz to 10 kHz
Span ±7199.999°
Frequency Sweep
Type Linear or log, phase continuous
Waveform Up, down, up-down, single sweep
Time 0.001 s to 1000 s
Span 1 mHz to 30.2 MHz (to 100 kHz for triangle, ramp)
Markers Two markers may be set at any sweep point (TTL output)
Sweep output 0 to 10 V linear ramp signal, synchronized to sweep
Burst Modulation
Waveform Any waveform except noise may be burst modulated
Frequency Sine, square to 1 MHz
Triangle, ramp to 100 kHz
Arbitrary to 40 MHz sample rate
Count 1 to 30,000 cycles/burst (1 µs to 500 s burst time limits)
Trigger Generator
Source Single, Internal, External, Line
Rate (internal) 0.001 Hz to 10 kHz (2-digit resolution)
External trigger Positive or negative edge, TTL
Output TTL level
Standard Timebase
Accuracy ±5 ppm (20 °C to 30 °C)
Aging 5 ppm/year
Input 10 MHz/N ± 2 ppm (N = 1 to 8) 1 Vpp minimum input level
Output 10 MHz, >1 Vpp sine into 50 Ω
Optional Timebase
Type Ovenized AT-cut oscillator
Stability <0.01 ppm, 20 °C to 60 °C
Aging <0.001 ppm/day
Allan variance (1 s) <5 × 10-11
General
Interfaces Optional RS-232 (300 to 19.2 kbaud, DCE) and GPIB with DOS based arbitrary waveform software (AWC). All instrument functions are controllable over the interfaces.
Non-volatile memory Nine sets of instrument settings can be saved and recalled
Dimensions 8.5" × 3.5" × 13" (WHL)
Weight 10 lbs.
Power 50 W, 100/120/220/240 VAC, 50/60 Hz
Warranty One year parts and labor on defects in materials and workmanship



Stanford Research Systems, Inc. • 1290-D Reamwood Ave., Sunnyvale, CA 94089
Phone: (408) 744-9040 • Fax: (408) 744-9049 • email: info@thinkSRS.com • www.thinkSRS.com
© Stanford Research Systems, Inc. 2003