HMC7891 Data Sheet
Rev. 0 | Page 10 of 11
APPLICATIONS INFORMATION
RF FRONT-END PROTECTION
The HMC7891 is suitable for use in the front end of a wide
variety of RF systems, with an input limiting range of −30 dBm
to +10 dBm built in, removing the need for an additional
standalone limiter to protect other components in the system.
With a low noise figure of 3.5 dB, a high gain of 47 dB, and a
wide bandwidth of 2 GHz to 18 GHz, the HMC7891 is well
suited for modern radar, communications, electronic warfare,
and multifunction systems.
FREQUENCY TRIPLING
When the HMC7891 is driven into hard saturation, the limiting
response creates a strong third harmonic at the output. Figure 14
shows the typical third harmonic output levels relative to the
fundamental output tone. The HMC7891 can be used as a
wideband analog frequency tripler due to this response.
As an example, an input tone at 4 GHz with a power level of
10 dBm produces a 13 dBm fundamental output tone at 4 GHz,
as well as a third harmonic at approximately 4.5 dBm (−8.5 dBc) at
12 GHz. The RF output can then be followed with a band-pass
filter centered at 12 GHz to filter out the fundamental output
and other harmonics.
GAIN EQUALIZATION
Many wideband RF components have an undesirable amount of
gain variation or negative gain slope over frequency. Components
and systems requiring gain equalization can be connected to the
input of the HMC7891, resulting in a flatter response.
The limiting amplifier output saturates with inputs ranging from
−30 dBm to +10 dBm for a total limiting dynamic range of 40 dB.
The saturated output power is flat over frequency and temperature,
making the HMC7891 a versatile equalizer suitable for a variety
of environments.
