Low-Noise Preamplifier (Model LNA10) for use with oscilloscopes
Low-Noise Preamplifier (Model LNA10) for use with oscilloscopes, view of BNC input jacks
Low-Noise Preamplifier (Model LNA10) for use with oscilloscopes, view of BNC output jack
Low-Noise Preamplifier (Model LNA10) feature sheet

Oscilloscope Preamplifier LNA10

$385.00

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

SKU: LNA10 Category: Tags: , ,

Description

With the LNA10 oscilloscope preamplifier, sub-microvolt signals can be displayed on oscilloscopes which typically only go down to 1mV/div on the vertical axis.  This preamp includes an analog true differential input and an analog low-pass filter (tunable 1Hz-1MHz).  Input-referenced RMS noise spectrum for f >100Hz is 4nV/√Hz or less. So for example, even with 1000 x gain, total noise from 100 Hz to 1000 Hz 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-frequency (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.* Most amplifiers have a white noise spectrum (a flat spectral curve) at all frequencies above ~1000 Hz.  This white noise spectrum is usually specified as a certain number of nV per √Hz.  However, unlike typical passive resistors, the equivalent input noise spectrum of solid-state amplifiers (in nV/√Hz) becomes higher at low frequencies.  Typically the number of nV/√Hz is proportional to ~1/f for f ≤10Hz. The Noise Characteristics table (located under Specifications) 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.

*The intrinsic “white” noise of a resistive electrical circuit at room temperature is proportional to √(R∙Δf), 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 Ω resistor will have an intrinsic RMS noise of 13 nV in a Δf =10 Hz bandwidth, with 10 Hz being the bandwidth, for example, associated with the frequency range 0-10 Hz,  or with the frequency range 102 Hz-112 Hz.  The noise will become twice as much if the bandwidth being studied is 4 times as wide (i.e., 40 Hz), or if the resistance is multiplied by 4.

 

Specifications

Gain Selectable 10x/100x/1000x (true differential, with CMRR > 90dB)

Positive and negative single-ended inputs can be selected, as well as reference ground

(LNA10 does not have 1x gain)
Gain Accuracy +/-1%
Output Filter Single Pole Low Pass, tunable from 1Hz to 1Mhz

(used to reduce bandwidth, as needed)
Input Signal Coupling Selectable AC or DC

AC passes through a .3Hz High Pass filter, 1 pole. When AC coupled, an offset as much as +/-30V can be tolerated at the input. In this case, if the inputs rapidly vary by more than .8V peak-to-peak, then the slew rate must be ≤ 2V/sec for accurate amplification.

DC, each input must be between -0.4V and +0.4V, with respect to case ground, for accurate readings.
Input Offset Adjustment +/- 1 mV 
Input Protection +/- 5KV ESD (static).

+/-30V unlimited current transients, with respect to case ground.
Input Impedance 1MΩ
Input type BNC
Output Impedance 470Ω
Output Type BNC (100Ω)

The output is designed to be connected to a single oscilloscope channel, or any other voltage-reading device (data logger, voltmeter, etc).
Input Power 12VDC (~50mA min)

Noise Characteristics

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

*The intrinsic “white” noise of a resistive electrical circuit at room temperature is proportional to √(R∙Δf), 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 Ω resistor will have an intrinsic RMS noise of 13 nV in a Δf =10 Hz bandwidth, with 10 Hz being the bandwidth, for example, associated with the frequency range 0-10 Hz,  or with the frequency range 102 Hz-112 Hz.  The noise will become twice as much if the bandwidth being studied is 4 times as wide (i.e., 40 Hz), or if the resistance is multiplied by 4.

LNA10 Demonstration

 

Additional information

applications

Electrical Engineering, Scientific Research
category

Voltage Measurement