CHEMANDY ELECTRONICS Suppliers of the unusual

1 GHz Broadband Amplifier in Original FLEXI-BOX


Broadband Amplifier 300 KHz to 1 GHz
Gain > 13 dB @ 1 GHz
Output Power > +15 dBm @ 1 dB comp
IP3 @ 100 MHz +30 dBm
Input Return Loss > 14 dB from 1 MHz
Output Return Loss > 20 dB from 1 MHz
Impedance 50 Ohms
Supply 11 to 14 Volts @ 130 mA
Box Dimensions
63.5 mm x 50 mm x 30.5 mm


From GBP £35.68 + Connectors
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The price of the 1 GHz Broadband Amplifier  FLEXI-BOX is dependant on the connectors required. To find the price for your connector preference or to make a purchase, select your connector requirements in the boxes beside the photograph below and then select "Add to Cart". 



   [Photograph of Broadband Amplifier Box showing connectors]   



The 1 GHz broadband amplifier is built in an Original size FLEXI-BOX on a dedicated PCB. The box has one 50 Ω input and one 50 Ω output. It can be used as a test measurement aid or a general purpose wideband amplifier, but was originally intended for use in studying co-axial transmission lines. It also makes an excellent receiver pre-amplifier because of the low noise figure and the ability to handle large interfering signals. It was tested very successfully as an AIS pre amplifier when it was in its prototype stage. The connectors can be selected from BNC, N  SMA or TNC.  Other connector types could be fitted if required in quantity. It could therefore be used in many applications that require a broadband amplifier not just in the lab.


The amplifier is built around the Sirenza SGA-7489 DC - 3000 MHz Silicon Germanium HBT Cascadeable Gain Block. The basic performance is therefore similar to that achieved in their datasheet which can be obtained at  This component performs very well but has the disadvantage that it is really designed to be embedded within a circuit. When it used as a free standing component, it is very easy to destroy the device. We have added reverse supply protection and a constant current regulation circuit which affords some DC protection and also softens the adjustment of the supply volts. A further addition of a 6 dB attenuator on the output  helps to protect it from output mismatches. It also gives an improved output return loss and isolation. This does of course reduce both the gain and the output power level. It is however, still a very useful test aid and the 6 dB attenuator is required in all measurements made in our article Understanding Coaxial RF Transmission Lines by Measurement and Calculation anyway. So the need for an external attenuator in this case is avoided. The SGA-7489 is specified to 3 GHz and the performance to this frequency is shown in figures 1 & 2, but the conventional bandwidth is 1 GHz within a 3 dB output power bandwidth.


[Graph of broadband amplifier gain and isolation]

[Graph of broadband amplifier input and output return loss]

The above results were obtained with SMA connectors and the performance will most probably be inferior with any other connector type fitted.

 The escutcheon of the Broadband Amplifier can be customised for your personal preference and a selection of escutcheon drawings are available for downloading as .zip or .bmp files.