LNA 10, Low Noise Differential Preamplifier for Oscilloscopes

PSE Priggen

LNA 10, Low Noise Differential Preamplifier for Oscilloscopes

SKU: LNA10

Category: Measuring Instruments

differential, potential-free BNC input

BNC output (100 Ohm)

amplifier gain selectable: x10, x100, x1000

output low pass filter, tunable 1Hz to 1MHz

input offset adjustment: ±1mV

selectable input DC/AC coupling

734,23 €

incl. 19% VAT , plus

: 1 - 3 Workdays (DE - int. shipments may differ)

pcs.

: 1 - 3 Workdays (DE - int. shipments may differ)

LNA 10, Low Noise Differential Preamplifier for Oscilloscopes

The LNA 10 oscilloscope preamplifier will significantly improve the small-signal performance of oscilloscopes at frequencies below 1MHz.

With this preamp, sub-microvolt signals can be displayed on Scopes which typically only go down to 1mV/DIV on the vertical axis.
The preamp includes an analoge true differential input and an analogue low-pass filter (tunable 1Hz-1MHz).
Input-referenced RMS noise spectrum for F >100Hz is 4nV/square root Hz or less, so for example, even with 1000 x gain, total noise from 100Hz to 1000Hz is less than 1 DIV peak-to-peak on a 1mV/DIV vertical scope setting (assuming a low-impedance input). Most oscilloscopes are designed to display high-frequeny (fast) events that may intrinsically have noise of a millivolt or more. However, low-frequency signals have much less intrinsic noise, so a low-noise preamp and a bandwidth-limiting filter are essential for small signals at low frequency.

The intrinsic "white" noise of a resistive electrical circuit at room temperature is proportional to square root (R x delta f), which is the square root of the product of source resistance multiplied by the bandwidth being investigated. For low source resistance and low frequencies, noise is low. For example, a 1000 Ohm resistor will have an intrinsic RMS noise of 13nV in a delta f = 10Hz bandwidth, with 10Hz being the bandwidth, for example, associated with the frequency range 0-10Hz, or with the frequency range 102Hz - 112Hz. The noise will become twice as much if the bandwidth being studied is 4 times as wide (i.e. 40Hz), or if the resistance is multiplied by 4.

Most amplifiers have a white noise spectrum (a flat spectral curve) at all frequencies above ...1000Hz. This white noise spectrum is usually specified as a certain number of nV per square root Hz. However, unlike typical passive resistors, the equivalent input noise spectrum of solid-state amplifiers (in nV/square root Hz) becomes higher at low frequencies. Typically the number of nV/square root Hz is proportional to ...1/f for f < = 10Hz.
The table below shows actual noise of the LNA 10 in various frequency ranges. At all frequencies, the LNA 10 has much less noise than typical solid-state amplifiers.

Frequency Range:	Input-referenced Noise:
10-4- 10-2Hz (freq range: inverse of 2.8hrs to inverse of 100sec)	50nV RMS
10-2Hz - 1Hz (freq range: inverse of 100sec to inverse of 1 sec)	20nV RMS
1 - 10Hz	18nV RMS (6nV/ square root Hz average)
10 - 100Hz	39nV RMS (4.1nV/ square rootHz)
Above 100Hz	< 4nV/square root Hz

Features:

Max. bandwidth: DC to 1MHz (1MHz is at -3dB)
Output has a single pole lowpass filter, tunable from 1Hz to 1MHz. This feature reduces the bandwidth, as needed.
Selectable DC/AC coupled input ("AC" passes through a 0.3Hz highpass filter, 1 pole): On DC, each input must be between -0.4V and +0.4V, with respect to case ground, for accurate readings. When set to AC, a DC offset up to ±30V can be present. (However, if the inputs rapidly vary by more than 0.8V peak-to-peak, then the slew rate must be = 2V/sec for accurate amplification.)
Inputs are protected to ± 5KV static and ±30V unlimited current transients, with respect to case ground.
Selectable gains are x10, x100, x1000 (true differential, with CMRR > 90dB). Also positive and negative single-ended inputs can be selected, as well as reference ground. Gain accuracy: ±1%. (The LNA 10 does not include a 1x gain.)
Max. output voltage: ±4V
An offset adjustment, equivalent to ±1mV at the input, is present.
A BNC output (100 Ohm) is intended to be connected to a single oscilloscope channel, or to another voltage-reading device (data logger, voltmeter, etc).