Integer Frequency Divider 18 GHz

Frequency Divider Features

• Wide input frequency range from 100 kHz up to 18 GHz
• Two cascaded programmable 1 – 256 frequency dividers deliver wide range of division ratios, from 1 to 65536
• Two identical differential outputs allow connecting up to four loads
• Low phase noise ≤ -131dBc/Hz @1kHz offset (13.3. GHz signal, ÷14 division ratio)
• High SFDR ≥ 75 dB
• Flexible interactive control from the front panel and software control from USB

Frequency Divider Applications

• Test and Measurement Instrumentation
• Testing Automation
• Lab Testing, Prototype Systems

The G1182 is a low noise programmable integer frequency divider that covers a wide input frequency range from as low as 100 kHz GHz up to 18 GHz.  It has the following functional blocks:

• Buffered differential input, which accepts the wide signal range from -6dBm to +10dBm
• Two low-noise programmable 1–256 frequency dividers connected sequentially
• The fan-out buffer with two differential outputs, which can be used as four single-ended outputs, delivering -2 dBm output signal level on each output
• USB-enabled microcontroller, which handles divider programming from the front panel and from the USB link.

The division ratio is indicated on a 5-segment LED display on the front panel and can be controlled interactively by front panel buttons.  The control of the divider can also be performed by the software application through the USB connection (useful for automated applications).

The duty cycle of output signal is 50% at any division ratio.

Because of the low phase noise, low jitter, and high SFDR the divider can be used in precision measurements in research and production environments.

For the best performance please terminate unused inputs and outputs with 50 Ohm termination.

The design requires a single +12V, 2A DC supply.

Programmable Frequency Divider

You can program the G1182 either interactively from the front panel, or programmatically through the USB link.

The USB software API is described in a separate document.

The front panel has 5-digit LED indicator and three control buttons: “Mode”, “+” and “–“.

The “Mode” button cyclically switches between three control modes:

• Full Divider ratio control
• Divider #1 ratio control
• Divider #2 ratio control

In the Full Divider ratio control mode you change the combined divider ratio of both dividers ranging from 1 to 65536.  In this mode the LED indicator shows the combined divider ratio.  This mode is selected by default on the power up.

Because two 1–256 dividers are connected sequentially, not all divider ratios in the 1–65536 range are possible to set.  For example, if the divider ratio is divisible by a prime number greater than 256, such divider ratio is not possible to achieve.  The microcontroller automatically skips ratios which are not possible to achieve.

In the Divider #1 and Divider #2 ratio control modes you change the divider ratio of an individual 1–256 divider: #1 or #2.  In these modes the LED indicator shows the divider number (1 or 2) followed by dash, followed by the divider ratio or an individual divider.

For the best performance the microcontroller will not let you to select the divider #1 ratio smaller than the divider #2 ratio, or the divider #2 ratio greater than the divider #1 ratio.  In a case of such attempt the LED indicator will show  _ _ _ _ _  or  ¯ ¯ ¯ ¯ ¯  respectively.

The “+” and “–” buttons increment and decrement the selected divider ratio.  When “+” or “–” button is pressed once, the divider ratio changes to the next or previous available value.  When pressed and held for more than a second, the divider ratio starts changing with slow speed.  When you continue to hold a button, the divider ratio starts changing with faster speed.

When “+” and “–” buttons are pressed simultaneously they reset the selected divider to 1.

The selected divider ratio is automatically saved into the non-volatile memory and restored on the power up.

Specifications[1]

[1] Specifications are subject to change without notice

[2] Not all divider ratios are possible to set: if the ratio is divisible by a prime number > 256, such divider ratio is not achievable

[3] The phase noise increases for low slew rate input signals. It is recommended to use input signal with fast rise/fall time (≥ 4V/ns) for low frequency operations

[4] Limited by the signal source

Typical Phase Noise

13.3 GHz input signal, division ratios ÷1, ÷4, and ÷14

Figure 1

Typical SFDR

14 GHz input signal, div. ratio ÷2	18 GHz input signal, div. ratio ÷2
Figure 2	Figure 3