Two wideband, passive mixers from Analog Devices, the ADL5811 single-channel and ADL5812 dual-channel mixers, enable multi-band, single-board receiver designs by combining a wideband local oscillator amplifier, a programmable RF balun, a high-linearity mixer core, a programmable IF filter, and an IF amplifier. The mixers operate across the 700 to 2800MHz frequency range while delivering input IP3 (third order intercept) of 24dBm, an 11dB SSB noise figure and 7dB of power conversion gain, maintained across the frequency range. The mixers are designed for wideband wireless infrastructure applications and software-defined radio applications, including multi-band and multi-standard cellular basestation receivers, wideband radio link down converters, multi-mode cellular repeaters, and picocells applications. The limiting LO amplifier is capable of generating a high-voltage, fast-rise-time, square wave over a wide bandwidth with no DC current penalty compared to existing narrow band mixers. The mixers also offer the integration of a tuned, RF balun structure to ensure a well-balanced RF signal is applied to the FET mixer. Previously, narrowband mixers incorporated an RF balun consisting of a magnetic or transmission line transformer, which provided low loss but only moderate bandwidth, says the company. The mixer's structure is also innovative in that it generates a composite signal that could result in the early compression of the IF amplifier. The amplitude of the unwanted sideband is reduced into a load with a tuned filter network to provide the proper sum termination as a function of the RF and oscillator frequencies. Frequencies can be changed using a three-wire SPI, which allows designers to tune the mixers with no need for external impedance matching components. Digitally adjusting the DC bias voltage to the passive mixer gates also optimizes performance. To minimise power dissipation, each channel of the dual-channel ADL5812 can be enabled or disabled independent of the other. For digital pre-distortion transmit observation receivers or non-diversity applications, the single-channel ADL5811 can implement a single receiver chain in a multi-channel or multi-band platform.
