The DDS-generator GK101 is manufactured by a Chinese company Ginko. This generator is also available under the name IDSG101 of the company ITead. It’s a full analogue. The average cost is around 100$ (on Aliexpress).

 

Direct Digital Synthesizer (DDS) is a type of frequency synthesizer used for creating arbitrary waveforms from a single, fixed-frequency reference clock.

Features

Standard Waveform: Sine, Square, Triangle, Sawtooth rise, Sawtooth fall, Sinc, Noise, Exponential rise, Exponential fall, Positive full-wave, Negative full-wave, Positive half-wave, Negative half-wave, Gaussian, DC
Sample Rate: 80 MS/s
Vertical Resolution: 14 bit
Arbitrary Waveform Length: 2 to 32 K points
Built-in storage: 128 M

Frequency Characteristics
Output range:
Sine: 1 mHz ~ 10 MHz
Square: 1 mHz ~ 10 MHz
Others: 1 mHz ~ 1 MHz
Resolution: 1 mHz
Accuracy : 50 ppm

Voltage characteristics
Output range: 10 mVpp~10 Vpp
Resolution: 12 bit
Accuracy: 8% of Setpoint
Offset Range: ±5V
Amplitude Flatness: ≥0.3 dB

Square characteristics
Duty Cycle: 0.1%~99.9% (1mHz~1MHz)
lock 50% (1MHz~10MHz)
Rise/Fall Time: < 20 ns
Overshoot: < 5%

General
Output Impedance: 50 Ω
Ramp Symmetry: 0.1%~99.9%
Sync signal: TTL ( 4.8 V~5.2 V )
Power requirements: DC ( 4.75 V~5.25 V, < 400 mA)
Display characteristics: 3-inch, 240×400 resolution
Dimensions (L x W x H): 116 mmx76 mmx26 mm
Weight: 180 g

The box and its contents:

Manual in English. Menu of the Generator is quite simple.

On one hand there are two GK101 connectors: synchronization and signal output. On the other hand microUSB and expansion interface (UART, I/O trigger).

Let’s connect the generator to the oscilloscope Hantek DSO5102B (100 MHz) and make measurements of various forms of signals with different frequency, amplitude, offset, etc.

Sine wave

Square wave

GK101 can generate symmetric to 10 MHz and a asymmetrical rectangular signal to 1 MHz with adjustable duty cycle (Duty_CYC).

As you can see, on the signal observed emissions. Let us consider in more detail:

As you can see from the screenshot above, the amplitude of the “needle” +1 volt, ie almost 6 volts!

Triangular

The maximum oscillation frequency of the triangular signal of 1 MHz. And you can adjust the symmetry (parameter SYMM, tab Symmetry), to provide a ramp.

Other signals

For other signals maximum generation frequency is 1 MHz

Arbitrary waveforms

In this mode, you can generate a form with the number of points to 32768. For more information about how to create forms that are loaded into the device will be discussed in the second part of the article.

In this mode, you can make package of impulses. The shape and parameters of the signal are specified in tab Function.

Cycle – sets the duration of one cycle
Number – number of pulses in one package

It supports automatic and manual formation of packages, as well as the trigger.

Sweep generator

In this mode, the output signal is generated with time-varying frequency.  There are two submodes:
Linear – frequency varies linearly
LOG – frequency varies logarithmically

The Time parameter specifies the time during which the frequency changes.

Utility

The utilities tab contains system information and settings.

Input – method set the parameters of the signal: using numbers or arrows.

Memory banks to save the settings, signal

The inside of the generator

In the generator using FPGA Altera MAX II EPM240T100C5N (PDF)

As the DAC chip is used by Texas Instruments DAC904E (PDF) – 14-bit, 20 MHz

On the other hand motherboard installed chip RAM memory IS61WV6416BLL (PDF)

For its price GK101 – I think a pretty good generator. At least around 100$ I didn’t find worthy competitors. 

In the second part we will look at the process of updating the firmware, as well as the creation of arbitrary waveforms: the necessary software, links the process of creating, loading and generation of forms.

Manual GK101