Picotest J2111B Current Injector

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.

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.

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.

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

Applications Beyond Power Supplies

The J2111B extends to transistor characterisation, extracting small-signal current gain, transition frequency (Ft), and dynamic parameters. In RF and instrumentation circuits, it provides constant-current biasing for Class A amplifiers and buffers. Battery impedance measurement benefits from the injector's ability to sink current without introducing significant capacitive loading, preserving the accuracy of electrochemical impedance spectroscopy.

Safety and Compliance

Absolute maximum ratings must be observed at all times to avoid equipment damage or injury. Ensure output voltage remains within -60 to -1.5 V or +1.5 to +60 V. Between -1.5 V and +1.5 V, the J2111B will not operate reliably. For full specification compliance, maintain output voltage above 1.5 V or below -1.5 V. Never exceed 50 VAC or 75 VDC on the output terminals.