Ultra Linear RF Amplifier (32G QAM, OFDM)
In high speed optical communications most amplifiers are optimized for the amplification of binary bit sequences. In some applications, however, multilevel signals (e.g. as driving signals for optical QAM or PAM) or even analog signals (e.g. for optical OFDM) need to be amplified to drive the external modulator. These applications require the amplifier to have an even higher emphasis on the following parameters:
- High Bandwidth (fast rise and fall times)
- Minimum over- and undershoot (ringing)
- Bessel-roll-off characteristic in frequency response for linear phase
- High linear output power (high first order compression, P1dB & third order intercept point, IP3) to maintain a linear drive for a given modulator Vπ
A illustration of how these parameters affect the signal quality is exemplarily shown here.
The SHF S807, in particular, is an amplifier specifically designed for 4-level signals.
Below you will find a selection of SHF amplifiers with different gain and output drive to suit different input signal conditions and output amplitude to suit different modulator drive requirement for such complex signal generation. To judge linearity and characteristic of the individual amplifier, the 1dB & 3dB compression point and the third order intercept point are listed.
50 kHz - 65 GHz
35 kHz - 40 GHz
60 kHz - 50 GHz
SHF 806 E
40 kHz - 38 GHz
The SHF 100BP amplifier can be specially tuned for multi-level operation (option ML). This enables the device to perfectly amplify signals of up to 8 levels at data rates of more than 10 Gbps. An ideal source to drive this amplifier could be one of SHF’s digital-to-analog converters (DACs).
SHF 100BP Opt. ML
35 kHz - 14 GHz (typ.)