An electronic attenuator may be viewed as a variable resistor controlled by current through its control port. If a pure signal is applied at its input, harmonics will not be generated over most of the device’s operating frequency range; however, some amount of harmonics will appear at the very low frequency end of the band with the amplitude determined by input power level and frequency. The minimum insertion loss of an electronic attenuator will occur at the highest value of control current, 20 mA for Mini-Circuits’ models. The minimum insertion loss value will increase as frequency rises so that, for example, the 1-200 MHz PAS model will have a 1.4 dB insertion loss while the 100-2000 MHz PAS-2000 will have a 4 dB spec. Generally speaking, the return loss is a function of control current. The higher the control current, the higher the return loss (closer to 50Ω); as current decreases, return loss drops, resulting in a higher VSWR.

A useful feature of Mini-Circuits’ electronic attenuators is the ability for either a positive or negative control current to provide the same amount of attenuation between input and output; this makes it useful for biphase modulation applications. The computer- automated performance data (CAPD) included for Mini-Circuits’ electronic attenuators charts the phase difference between plus and minus modulation as a function of RF frequency.

The attenuators/switches are economically priced while covering the very broad frequency range from 1 to 2000 MHz. They offer low insertion loss (1.4 dB) high isolation (65 dB) and exceptional unit-to-unit matched performance.

Applications include power leveling and bi-phase modulation as well as current-controlled attenuation.

Figure 1

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