BCS-10 balanced current source module

This module provides programmable currents from 1 pA to 100 mA with a ±10 V maximum compliance output from DC to 100 kHz sinusoidal output. Derived from Lake Shore’s industry-leading Model 372 AC resistance bridge, the BCS-10 employs a differential or balanced design that helps reduce or eliminate ground loops often encountered in cryostats and other research apparatus. It expands on Model 372 balanced source capability, adding variable frequency and amplitude programmability for enhanced flexibility while maintaining excellent noise performance.

The inclusion of a virtual center-point ground connection further enhances noise performance by allowing the user to determine optimal center-point tie points within given apparatus or equipment setups. The BCS-10 is designed to be paired with the VM-10 module, which provides both single-ended and differential (balanced) input connection and modes.

A typical application of the balanced current source involves low-resistance measurements, where the resistance of the wires connecting the current source to a sensor may be significant. Any unbalance in lead wire resistance results in a common-mode voltage that complicates the measurement of the desired parameter, the voltage across the sensor. The external CMR feature is unique in that it allows the BCS-10 to force some remote node (such as a VM-10 input) to circuit common potential and thus mitigate the effect of unbalanced lead wire resistance.

BCS-10 specifications

Specifications subject to change

Ranges: 100 mA, 10 mA, 1 mA, 100 μA, 10 μA, 1 μA, 100 nA, 10 nA; automatic selection

Compliance: 20 V differential, 10 V single-ended (non-settable)

Maximum power: 1 W, 4-quadrant operation

CMR modes: Off, internal, external

Coupling: DC or AC (1 Hz)

Guard drive: Enable or disable

Settle time: 25 µs into 0 Ω

Load impedance: Stability maintained with reactive loads up to 50 µF or 1 mH (with 100 Ω damping)

Resolution (settable): 10 ppm of range

Module field exposure: Operational limit <5 mT DC (typical, normal mode)

Size: 142 mm W × 39 mm H × 89 mm D (5.6 in × 1.5 in × 3.5 in)

Bandwidth (typical)/accuracy

RangeBandwidth (-3 dB)DC1Lock-in1,2Temperature coefficient1,2
100 mA100 kHz0.15% + 70 µA0.15%8 ppm/°C
10 mA100 kHz0.15% + 7 µA
1 mA100 kHz0.15% + 700 nA
100 µA100 kHz0.15% + 70 nA
10 µA100 kHz0.15% + 7 nA
1 µA10 kHz0.25% + 700 pA0.25%
100 nA1 kHz1% + 70 pA1%
10 nA100 Hz1% + 40 pA

Noise (typical)

DC to 100 MHz: 2 mV RMS

RangeNoise at 1 kHzNoise at 0.1 Hz to 10 HzSettable resolution
100 mA2 nA/√Hz300 nA p-p1 µA
10 mA200 pA/√Hz30 nA p-p100 nA
1 mA30 pA/√Hz3 nA p-p10 nA
100 µA10 pA/√Hz300 pA p-p1 nA
10 µA10 pA/√Hz60 pA p-p100 pA
1 µA10 pA/√Hz60 pA p-p10 pA
100 nA10 pA/√Hz60 pA p-p1 pA
10 nA10 pA/√Hz60 pA p-p100 fA

1 1 year, ±5 °C from Lake Shore calibration
2 DC to 1 kHz

BCS-10 module options

Options for the BCS-10 module that you can set on the M81 instrument screen

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