Cryogenic SiGe Low Noise Amplifier
The CITLF3, a SiGe low noise amplifier, is intended for extremely low noise cryogenic applications. The amplifier uses resistive feedback to achieve good input match (S11) and high gain stability. The amplifier is optimum for the frequency range of 0.01 GHz to 4 GHz, but is usable to 5 GHz. Operates from below 4 K to 350 K.
It is powered from a single positive DC power supply which is optimum at 2.0 V, but can be changed to tradeoff power dissipation and performance as shown in the table and graph on the following page. Application of up to 5 V will not damage the amplifier. It is recommended that the power supply for the amplifier to be current limited to 100 mA. A series resistor may be used. For instance, 220 Ohms to a + 5 V supply will provide 2.0 V and 13.6 mA when the amplifier is at 12 K. The maximum RF input power to be applied to the amplifier without damage is +10 dBm.
The amplifier is 20.7 mm x 15.9 mm x 8.7 mm excluding connectors. Input and output female SMA connectors.
Optional Input Bias Tee
As an option, the amplifier can be supplied with a DC bias tee for an external device connected to the amplifier input. The bias tee is formed by two (2) resistors connected to the input. One (1) resistor can be used as a source of current and the other senses the voltage across the external device. Voltages applied to the bias tee have a small effect on amplifier operation. At 12 K, 20 KΩ resistors increase noise by 0.5 K. To order an amplifier with internal bias resistors, add the resistance to the part #. For instance, CITLF3-20K.
Optional Input Diode Protection
As an option, the amplifier can be supplied with ESD protection & voltage spike protection at the RF input to the amplifier. There will be a slight degradation of the amplifier performance. Please note that the optional input protection diodes cannot be used if DC voltages are applied to the RF line using input bias tees.