The OPA695 can also be used to buffer the local oscillator (LO) from the mixer. Operating at a voltage gain of +2 V/V, the OPA695 provides excellent load isolation for the LO, with a net gain of 0 dB to the mixer. Applications through a 1.4-GHz LO can be considered, but best operation is for an LO < 1.0 GHz at a gain of +2 V/V. Gain can also be provided by the OPA695 to drive higher power levels into the mixer. Figure 7-5 shows one option for the OPA695 as an LO buffer. The OPA695 can drive multiple output loads; therefore, two identical LO signals can be delivered to the mixers in a diversity receiver by tapping the output off through two series 50-Ω output resistors. This circuit is set up for a voltage gain of +2 V/V to the output pin for a gain of +1 V/V (0 dB) to the mixers, but can be easily adjusted to deliver higher gains.

Figure 7-5 Dual Output LO Buffer