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Picotest Injector

J2120A

J2120A-Picotest Line Injector 10Hz-10MHz(PSRR)

產品說明

10Hz-10MHz usable bandwidth

Low loss design

5 Amps maximum current

50VDC max input

Easily measure input filters and PSRR

While the injection transformer is a very wideband adapter, it is not useful for measuring ripple rejection (PSRR) of a power supply or even an opamp. This is because the attributes that make the injection transformer perform so well also result in a transformer that is intolerant of DC current. Even very small DC currents (5mA or less) can greatly reduce the signal capacity or even totally saturate the transformer. For this reason, the Picotest line injector (J2120A) is another essential test adapter.

The line injector allows the input DC supply voltage to be modulated by the network analyzer source signal, as in the case of a PSRR measurement. The line injector must be capable of a frequency range well below the AC line frequency and at least above the control loop bandwidth of the circuit being tested.

The line injector is only capable of sourcing current, so that the output amplitude can be significantly impacted by the operating current and the total storage capacitance at the load. The Bode-100 network analyzer has a very high selectivity so distortion at the output of the line injector generally does not influence the measurement. Again, this is a small signal injector, so the oscillator signals should be kept as small as possible above the noise floor. As a guide, try to keep the input signal amplitude below 50mVpp (-20dBm). In some cases we want to attenuate the source signal even further, and so we have included the attenuators in the injector kits. Some analyzers, such as the Omicron-Lab-Lab Bode-100 allow shaping the injection amplitude as a function of frequency, which helps optimize the signal level.

Measuring Input Impedance
The line injector can also be used in conjunction with a current probe to measure the input impedance of a power supply. The input impedance of a switching power supply or regulator is negative, which is a stability concern when combined with an EMI filter, making the measurement an important part of the design, analysis and verification process. The current probe must be set for 1A/V or the results need to be scaled accordingly for different settings.

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What's included :

1. J2120A Line lnjector
2. User manual
3. 1 Year Warranty

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規格說明

Specifications
Characteristic	Typical
Maximum DC Input Voltage	50VDC
Maximum Continuous Current	5A
Maximum Voltage Drop	3.25VDC
Modulation Input Impedance	10K ohms
3dB Frequency Response	15Hz ~ 5MHz
Useable Frequency Response	10Hz ~ 10MHz
Recommended Injection Signal	-20dBm ~ 0dBm
Temperature Range	0 ~ 50°C
Maximum Altitude	6000 Ft
Absolute Maximum Voltage	< 50V (DC + AC)

J2120A is the lowest impedance injector on the market and can be approximated by the following relationship to operating current.

Or about 180mOhms at 1Amp
Caution: To avoid equipment damage and/or severe injuries or death ensure that the absolute maximum ratings are observed and not exceeded at all times.
EMI Note: Exceeding 0dBm may cause the unit to exceed CE EMI limits.

Solution Page

POWER SUPPLY REJECTION RATIO MEASUREMENT

PSRR for Opamp and Voltage References

PSRR is an important parameter to measure for Opamp and votage references. PSRR is a significant performance concern as even small amounts of high frequency ripple voltage at the input can significantly degrade the output precision of voltage reference and impact downstream circuitry. The output of the Op Amp is not only a function of the inputs, but also of the power supply.