Picotest J2111B Current Injector

Product Code: J2111B

High-Bandwidth Current Injection for Power Integrity Analysis The Picotest J2111B Current Injector delivers uncompromising performance for power supply output impedance measurement, non-invasive stability testing, and high-speed load transient analysis. Engineered for demanding applications where precision matters, this voltage-controlled current sink operates from DC to 40 MHz with typical rise and fall times of 20 nanoseconds, enabling accurate characterisation of modern switching regulators, LDOs, and PDN architectures. Bidirectional Operation for Maximum Versatility Unlike unipolar alternatives, the J2111B features two-quadrant operation, sinking current from either positive or negative voltage sources. This bipolar capability supports testing across voltage ranges from +1.5 V to +60 V and -1.5 V to -60 V, accommodating everything from low-voltage point-of-load regulators to automotive and industrial power systems. The controllable output current variation spans 50 mA, with an additional ±25 mA DC offset providing a total range of 74 mA peak.

Built-In Current Monitoring and 50 Ω Integration A precision current monitor output delivers 1 V per amp scaling into 50 Ω, integrating seamlessly with vector network analysers, oscilloscopes, and DMMs. The modulation input accepts signals from arbitrary waveform generators (such as the Picotest G5100A), function generators, or network analysers. With 10 mA/V voltage-to-current scaling (40 dB attenuation), the J2111B enables precise control of injected current profiles for load step testing, PDN impedance sweeps, and control loop stability analysis. Key Specification: Modulator gain of 10 mA/V with 50 Ω input impedance ensures compatibility with standard laboratory instrumentation. Three-Port Impedance Measurement When paired with a voltage probe and network analyser, the J2111B facilitates three-port impedance measurements, calculating output impedance as the voltage-to-current ratio (V/I). This technique proves invaluable for measuring regulator output impedance, battery impedance, and power bus characterisation. The method works particularly well for voltages ≥12 V where the 25 mA bias current represents a minor perturbation. Parameter Specification Unit Output Current Variation (Controllable) 50 mA Total Output Current (Controllable + Bias) 74 mA Modulator Gain 10 mA/V Current Monitor Scaling 1 V/A Usable Bandwidth DC–40 MHz Rise/Fall Time (Typical) 20 ns Absolute Output Voltage Range -60 to -1.5, +1.5 to +60 V Max Input Voltage (DC+AC) ±5 V Offset Current (Typical) +24/0/-24 mA Modulation Input Impedance 50 Ω Current Monitor Output Impedance 50 Ω Operating Temperature 0–50 °C Maximum Altitude 6000 ft Absolute Maximum Voltage <50 VAC, 75 VDC — Non-Invasive Stability Measurement (NISM) The J2111B enables Non-Invasive Stability Measurement, a technique that derives phase margin from output impedance data when traditional Bode plot access is unavailable. NISM proves particularly valuable for fixed-output LDOs, voltage references, and integrated POLs where feedback pins are inaccessible. When used with OMICRON Lab Bode 100 or Keysight E5061B analysers, NISM software converts impedance measurements into phase margin values accurate to within 1 degree of traditional control loop analysis. High-Speed Load Transient Testing Traditional electronic loads suffer bandwidth limitations, capacitive loading, and slow slew rates. The J2111B overcomes these constraints with minimal output capacitance and 20 nanosecond edges. Drive the injector with arbitrary waveforms to simulate battery discharge profiles, high-speed digital load currents, or spontaneous current spikes. The fast response reveals regulator behaviour under transient conditions that conventional e-loads cannot replicate, exposing stability margins, underdamped ringing, and voltage droop. Application Note: When measuring output impedance, keep interconnection inductance low. Short, wide traces or low-inductance coax preserve high-frequency accuracy. Consider using the Picotest J2102B ground loop breaker to minimise measurement errors from common-mode currents. Power Supply and Included Accessories The J2111B ships with the J2171A High PSRR Regulated Adapter, a purpose-designed universal input power supply (100–240 VAC). Unlike generic switching adapters that introduce ripple above 100 kHz, the J2171A employs discrete linear regulators with ultra-high power supply rejection ratio and exceptionally low output impedance at 40 MHz. This ensures the measurement noise floor remains uncompromised by supply-induced artefacts. Comparison: J2111B vs J2112A Feature J2111B J2112A Maximum Current Output 75 mA (50 mA + 25 mA bias) 1 A (240 mA minimum) Voltage-to-Current Scaling 10 mA/V 200 mA/V Polarity Bidirectional (positive/negative) Unipolar (positive only) Voltage Range -60 to -1.5 V, +1.5 to +60 V +0.7 to +50 V Bandwidth DC–40 MHz DC–50 MHz Rise/Fall Time 20 ns (typica