Ultra low noise preamplifiers
We offer a range of ultra-low noise preamplifiers. These come as part of our complete detector systems, and are also available individually. The circuitry is housed in a shielded enclosure and is designed to mount directly to a detector cryostat output port to reduce interference and minimise the distance travelled by the un-amplified signal. The amplifier has an external power supply option for continuous operation. Input-shorted noise is around 1 nV/rtHz at 1 kHz, which noise-matches source impedances as low as 2 kOhms at 4 K.
All our amplifiers are voltage mode, low noise preamplifiers designed for use with cooled detectors.
The models available are (click on the model name for more information):
- ULN95 - a single channel amplifier
- ULN95/2 - similar to the above, but with two channels
- ULN96 - as above, but with five channels
|Output impedance||50 Ohm BNC|
|Input impedance||> 10 GOhm|
|Voltage Gain options||x100, x1000|
|RMS (input shorted) output noise at 1 kHz||1 nV Hz-1/2 (approx.)|
|RMS (input shorted) output noise at 10 Hz||3 nV Hz-1/2 (approx.)|
|Bandwidth||0.5 Hz to > 750 kHz|
|Number of channels||Model dependent|
ULN95 single channel pre-amplifier
The ULN95 can be powered either from internal rechargeable batteries or from an external ±15V DC supply. Switchable gain options, a potentiometer bias supply control and full detector status monitoring are provided. Output is 50 Ohm BNC as standard, and the circuit is housed in an EMI/RF shielded enclosure designed to mount directly to the detector cryostat to reduce interference and provide a common ground.
The input impedance is high, so the preamplifier can be used with a range of cooled detectors, including InSb hot electron bolometers (types QFI/X, QFI/XB and QFI/XBI) and composite Silicon and Germanium bolometers (types QSIB/X and QGeB/X).
The ULN95 single channel preamplifier
The following labelled two pictures give internal views of the ULN95 showing the circuit boards, battery packs, fuses and connections.
View of the amplifier board
ULN95/2 Two channel preamplifier
The ULN95/2 is a two channel version of the ULN95 preamplifier. Each EMI/RFI shielded unit accommodates two power supply boards and two amplifier boards. See above for the specifications.
As with the single channel ULN95 preamplifier, this unit may be used with our range of cooled detector systems.
ULN96 five channel preamplifier
The ULN96 is a multi-channel version of the highly successful ULN95 preamplifier. Each EMI/RFI shielded unit accommodates the motherboard, power supply card and up to five amplifier cards. A space is left free for remote control. Specifications are given above. The unit mass is 8 kg, and the dimensions are: depth = 90 mm, width = 115mm, height = 260mm.
The ULN96 five channel preamplifier supplied with four outputs
All boards are located via edge connectors for easy replacement if necessary. The unit can be powered either by a rechargeable battery stack included within the housing, or via a laboratory power supply. Full battery status, power consumption and recharge monitoring are provided.
The following photos show the motherboard with the power supply board and two amplifier boards plugged into it.