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
| Range | Bandwidth (-3 dB) | DC1 | Lock-in1,2 | Temperature coefficient1,2 |
| 100 mA | 100 kHz | 0.15% + 70 µA | 0.15% | 8 ppm/°C |
| 10 mA | 100 kHz | 0.15% + 7 µA | ||
| 1 mA | 100 kHz | 0.15% + 700 nA | ||
| 100 µA | 100 kHz | 0.15% + 70 nA | ||
| 10 µA | 100 kHz | 0.15% + 7 nA | ||
| 1 µA | 10 kHz | 0.25% + 700 pA | 0.25% | |
| 100 nA | 1 kHz | 1% + 70 pA | 1% | |
| 10 nA | 100 Hz | 1% + 40 pA |
Noise (typical)
DC to 100 MHz: 2 mV RMS
| Range | Noise at 1 kHz | Noise at 0.1 Hz to 10 Hz | Settable resolution |
| 100 mA | 2 nA/√Hz | 300 nA p-p | 1 µA |
| 10 mA | 200 pA/√Hz | 30 nA p-p | 100 nA |
| 1 mA | 30 pA/√Hz | 3 nA p-p | 10 nA |
| 100 µA | 10 pA/√Hz | 300 pA p-p | 1 nA |
| 10 µA | 10 pA/√Hz | 60 pA p-p | 100 pA |
| 1 µA | 10 pA/√Hz | 60 pA p-p | 10 pA |
| 100 nA | 10 pA/√Hz | 60 pA p-p | 1 pA |
| 10 nA | 10 pA/√Hz | 60 pA p-p | 100 fA |
1 1 year, ±5 °C from Lake Shore calibration
2 DC to 1 kHz
Options for the BCS-10 module that you can set on the M81 instrument screen
